Consequences of Thought Speed

CHAPTER FOUR

Kaite Yang*, Emily Pronin†,1 *School of Social and Behavioral Sciences, Stockton University, Galloway, NJ, United States †Department of Psychology, and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, United States 1Corresponding author: e-mail address: [email protected]

Contents 1. Introduction 168 1.1 The Idea of Thought Speed 169 1.2 Outline for Chapter 170 2. Thought Speed Affects Mood and Emotion 171 2.1 Manic Thinking: An Initial Demonstration 171 2.2 The Speed–Mood Link 174 3. More Consequences of Thought Speed 178 3.1 Fast Thinking Increases Risk-Taking 178 3.2 Fast Thinking Increases Purchasing Interest 181 3.3 Fast Thinking Enhances Creative Insight 185 3.4 Fast Thinking Elevates Self-esteem 189 3.5 Fast Thinking Is Arousing 191 4. Thought Speed and Related Constructs 192 4.1 Speed and Fluency 192 4.2 Speed and Dual Process Theories of Thinking 195 4.3 Speed and Mental Progression 196 5. How Thought Speed Works 197 5.1 The Basic Idea 197 5.2 Dopamine 199 5.3 Embodiment and Entrainment 201 6. Thought Speed and Treatment for Depression 202 6.1 Direct Experimental Tests 203 6.2 Bipolar Disorder 206 7. Methods of Manipulating Thought Speed 207 7.1 Rapidly Presented Stimuli 207 7.2 Speed-Inducing Cognitive Activities 209 7.3 Musical Tempo 209 7.4 Pharmacological and Physiological Alterations 210 7.5 Time Perception 210

8. Some Future Directions for Thought-Speed Research 211 8.1 Thought Speed and Psychophysiology 211 8.2 Thought Speed and Cognition 212 8.3 Thought Speed and Communication 212 9. Conclusion: Thought Speed in the Modern World 213 References 214

Abstract The speed of thinking is a frequently overlooked aspect of mental life. However, the pace of thought is an essential property of thinking, and its consequences have recently begun to be discovered. In this chapter, we review the psychological consequences of accelerated and decelerated thought pace. We begin by examining how the manipulation of thought speed alters mood, self-perception, risk-taking, creativity, and arousal. We highlight the energizing, activating, and hedonic effects of fast thinking, and we show how thought-speed effects are independent of thought content, fluency, and goal progress. We describe an adaptive theory of thought speed wherein psychological responses to the acceleration of thinking confer adaptive advantages for confronting novel, urgent, and rapidly changing situations, and engaging in behaviors driven by appetitive motivation. Lastly, we discuss implications of thought speed and its manipulation for treatment of mental illness, for design and delivery of communications and messages, and for life in the age of rapid access and exposure to information.

1. INTRODUCTION

We may never have met, but there is something I can say about you with complete certainty: Right now, at this very moment, you are thinking. There is no way that you could be reading this without doing it. You prob- ably could go hours or even days without eating, drinking, speaking, or even checking e-mail, but you could not go that long without thinking. Even when your mind wanders to no place special, you are thinking. Even when you try not to think about anything, you are thinking (perhaps about trying not to think). Nothing may be more fundamental to human existence than the ongoing action of the mind. So thought Descartes who, in what is likely the most famous line in the history of philosophy, claimed: “I think, therefore I am.” Not surprisingly, then, people devote a good deal of attention to the content of their thoughts. They tell others what they think about topics ranging from politics, to reality TV, to where to get a good meatball sandwich. They choose friendships, careers, and vacation destinations after first consulting their thoughts on which choice to make. People even analyze their dreams, Consequences of Thought Speed 169 looking for meaning in thoughts that emerge when they are not controlling them. The research that we review herein, though, speaks to another aspect of thinking—one that has more recently become an avenue for examining the nature of thought. That aspect involves not WHAT we think about, but rather HOW we think about it. In particular, the specific case of our work, and other work related to it, investigates the consequences of not the content of our thoughts but rather the SPEED, or the pace, with which we have those thoughts. It has long been known that thoughts with positive content make people happy compared to thoughts with negative content (e.g., Velten, 1968). Children are taught the old trick, memorialized in the musical The Sound of Music, of trying to alleviate a sad mood by thinking of their “favorite things” (Wise et al., 1965). The past decade of research on thought speed suggests a new trick for alleviating a sad mood: thinking about things really fast. Although Rodgers and Hammerstein did not write about it, thinking fast about favorite things like “raindrops on roses” and “whiskers on kittens” alleviates sadness far better than thinking slowly about those very same things. It is this pair of simple insights, that the pace of thought can be accelerated and that such accelerations impact mood, that provides the starting point for our investigations of the consequences of thought speed. But before describing this fundamental speed–mood connection, we turn to a brief discussion of the thought-speed concept.

1.1 The Idea of Thought Speed Thought speed in its essence involves the number of thoughts that one is having per unit of time. Until recently, the idea of thought speed came up only rarely in scientific discussions—and was not a variable that was manipulated; consequently, its effects were not measured or known. The idea of thought speed as an important variable is not entirely new, though. In the psychiatric literature, associations between various mental disorders and the speed of thought have long been noted. Individuals experiencing mania, for example, typically exhibit the hallmark symptoms of “racing thoughts” and “flight of ideas” (Hanwella & de Silva, 2011; Mansell & Pedley, 2008). Indeed, this symptom may be even more common than the stereotypic manic symptom of euphoric affect in predicting the onset of a manic episode (Keitner et al., 1996; Mansell & Pedley, 2008; Molnar, Feeney, & Fava, 1988). Individuals suffering from depressive episodes experience the opposite end of the thought-speed spectrum, with their 170 Kaite Yang and Emily Pronin thoughts sometimes slowed to the point of feeling immobilized (Caligiuri & Ellwanger, 2000). Another psychiatric disorder, ADHD or attention-deficit/ hyperactivity disorder, also has been associated with abnormal thought speed, with at least some of those experiencing it having “sluggish cognitive tempo” (Becker, 2013). Thought speed has also sometimes been recognized as a feature or symptom of experiences not involving psychiatric disorder. Certain mind-altering drugs, for example, are known to make thoughts race, including stimulant drugs such as cocaine and amphetamines (Asghar, Tanay, Baker, Greenshaw, & Silverstone, 2003; Heilbronner & Meck, 2014; Kirkpatrick et al., 2016; Vollm et al., 2004), as well as more pedestrian drugs such as caffeine and nicotine (Childs & de Wit, 2006; Durlach, Edmunds, Howard, & Tipper, 2002; Edwards, Wesnes, Warburton, & Gale, 1985; Hinton & Meck, 1996; Smith, 2002; Smit & Rogers, 2000; Warburton & Mancuso, 1998). Also, in everyday life, people experience fluctuations in their thought speed even when mental disorder and drugs are not part of the picture. For example, drinking the first cup of coffee in the morning may be a reaction to the unpleasant feeling that one’s thoughts are too slow. Lying awake at night with a bout of insomnia, one may lament that one’s thoughts will not slow down. On the other hand, when participating in a productive brainstorming session, one may instead delight in the feeling of one’s thoughts racing along. In each of the above examples of fast and slow thought speed, the pace of thought seems to be a symptom of some other condition—whether it be mental illness, drug intake, tiredness, insomnia, or creative excitement. However, we would argue—and have begun to show in our experimental work—that thought speed is important not only as a symptom in psychological life but also a cause of various aspects of psychological life. By manipulating thought speed through controlled experimentation, we demonstrate that the pace of thought has wide-ranging consequences. This research development is particularly important because thought speed is quite ame- nable to alteration—and fluctuates and varies during the course of everyday human experience.

1.2 Outline for Chapter In this chapter, we begin by reviewing basic evidence for a causal link between positive mood and the speed of thinking. From there, we discuss other consequences of thought speed, most notably consequences for self- perception, risk-taking, creativity, and mental health. Following this review, Consequences of Thought Speed 171 we offer a theoretical account to explain why thought speed impacts these various important aspects of psychological life. Finally, we discuss the impor- tance of thought speed in the context of modern life, where the speed of exposure to stimuli—especially digital information and communications— seems to be accelerating more every day. In reviewing this material, we present an inclusive review of consequences of thought speed as well as a theoretical framework for those effects. We describe how thought speed, thought content, and behavior covary in predictable patterns. Fast thinking is associated with what might be called an activated state: positive mood, energy, arousal, confidence, risk-taking, approach behaviors, and problem-solving. We describe a variety of ways in which thought speed can be experimentally manipulated to produce changes in affect, perception, and behavior. We also describe psychophysiological mechanisms that may facilitate the connections between speed, thinking, and behavior, including activation of the dopaminergic system and the phenomena of embodiment and entrainment. In this review, we discuss the evidence for these findings, as well as our ongoing experimental research program on thought speed. We also discuss implications of this work for treatment of mental illness (an area where experiments from our laboratory have begun to offer some promise) and for modern social life.

2. THOUGHT SPEED AFFECTS MOOD AND EMOTION

Most of us will never know firsthand what it feels like to be climbing an icy mountain, lose our footing, start falling hundreds of feet, and think we are about to die. Researchers Noyes and Kletti (1972) found something sur- prising in the accounts of hundreds of mountain climbers (and others) who have had near-death experiences: Rather than feeling despair, they often reported feeling oddly joyful and euphoric. Almost all of them reported that they experienced an acceleration of thinking when they believed that they were about to die. They expressed amazement at the rapid stream of mental images and thoughts passing through their minds in what amounted to a fraction of a minute. We now review our initial experiment showing that this experience of mental speed may not have been a side effect of their joy or euphoria but rather a cause.

2.1 Manic Thinking: An Initial Demonstration Pronin and Wegner (2006) provided the first direct test of the causal impact of thought speed on mood. In that study, we described the inspiration for 172 Kaite Yang and Emily Pronin our hypothesis in episodes of clinical mania, in which individuals almost always report both racing thoughts and elated mood. The experiment aimed to test whether people’s positive mood would be elevated in response to an experimental manipulation of thought pace. No predictions about negative mood were made, as mania does not have a stable profile in terms of negative affect (i.e., irritability is not uncommon, but also not a hallmark symptom like euphoria). In the experiment, participants were induced to think at either a fast or a slow rate by being induced to read text that was presented to them on a computer screen at either a fast or a slow rate. In order to investigate whether effects of thought speed would operate independently of thought content, participants were induced to read one of two sets of content: either the positive mood version of the Velten (1968) mood induction stimuli or the negative mood version of those stimuli. In the positive mood version of the Velten, participants read a series of statements that progressed from emotionally neutral (“Today is no better or worse than any other day”) to extremely excited and happy (e.g., “I’m going to have it all!”; “Wow! I feel great”). In the negative mood version of the Velten, the statements progressed from the same neutral starting point (“Today is no better or worse than any other day”) to very depressed in tone (e.g., “I feel worthless”; “I want to go to sleep and never wake up”). In order to manipulate thought pace, participants were induced to read the Velten statements at a pace that was controlled by computer presentation of streaming text. The statements streamed across participants’ computer screen at either a fast pace (40 ms per letter) or a slow pace (170 ms per letter). These precise speeds were selected based on pretesting to find the average reading speed for our participant population (of college undergraduates). The fast-speed condition was designed to be roughly twice as fast as that reading speed, and the slow-speed condition was designed to be roughly half that speed. The Pronin and Wegner experiment employed a 22 between- participants design, in which 144 participants were exposed to either fast or slow streaming text involving either elating or depressing content. Prior to the reading manipulation, participants indicated pretest positive and negative mood using a subset of the Positive and Negative Affect Schedule (PANAS; Watson, Clark, & Tellegen, 1988). Following this assessment of baseline mood, participants completed the reading manipulation. An experimenter instructed participants to read aloud the statements on a computer screen, keeping pace with the timed presentation of the statements. Following the speed manipulation, participants reported their subjective Consequences of Thought Speed 173 thought speed and their current mood. They also completed a number of other measures probing for additional reactions that might be induced by fast thinking. These were: feelings of energy, power, creativity, and self-esteem. The results revealed the predicted effect of thought speed on the measure of positive mood. Participants reported more positive affect after being induced to read quickly than after being induced to read slowly (see Fig. 1). Moreover, this effect was mediated by differences across the speed conditions in participants’ reported thought speed. That is, the reading- speed manipulation altered participants’ reported thought speed, and differences in reported thought speed mediated the effect of reading speed on positive mood. But, was this result due to the mood-enhancing effect of fast thinking, or was it due to the mood-depleting effect of slow thinking? Follow-up analyses (reported in Pronin & Jacobs, 2008) revealed that both of these effects were present. Participants who were induced to think quickly reported more positive affect after the fast-speed induction than before it, whereas participants who were induced to think slowly reported less positive affect after the slow-speed induction than before it (and both effects were statistically significant). Because the experiment manipulated both thought pace and thought content, we were able to examine whether thought pace induced its effects independently of thought content—and also how the size of the two effects compared with each other. Notably, thought pace operated independently of thought content (see Fig. 1). Both pace and content exerted significant effects, and there was no interaction between the two factors. Also notably, the effect of thought pace was at least as strong (if not stronger) than the effect of thought content. This is especially noteworthy given that the thought-content manipulation was not one that the experimenters devised but rather is a widely studied and replicated manipulation designed for the sole purpose of manipulating mood.

Slow 7 Fast 6 5 4 3 Positive mood Positive

Depression Elation Fig. 1 The effect of thought speed on positive mood, independent of depressed vs elated thought content (based on experiment by Pronin & Wegner, 2006). 174 Kaite Yang and Emily Pronin

Apart from positive mood, a number of other psychological responses found in episodes of clinical mania were examined. These were: feelings of increased energy, power, and creativity, as well as grandiosity/inflated self-esteem. Compared to participants in the slow thought-speed condition, those in the fast thought-speed condition reported greater feelings of energy, power, and creativity; however, the thought-acceleration manipulation only marginally increased grandiosity and did not inflate self-esteem. We did not have specific predictions concerning negative mood, as both mania (a disorder characterized by accelerated thinking) and depression (a disorder characterized by slowed thinking) can involve negative affect—with manic episodes sometimes involving irritability, for example (e.g., Mansell & Pedley, 2008). The thought-speed manipulation did not impact negative mood (though the thought-content manipulation did impact it, consistent with previous research on the Velten mood induction as a mood manipulation). This experiment constitutes the first demonstration of the mood- uplifting effects of fast thinking. Importantly, it showed that the effect of speed is independent of thought content. In the case of this experiment, the effect of speed was also at least as strong as that of thought content—even with a well-established manipulation of thought content. Indeed, as can be seen in Fig. 1, reading depressive content fast induced participants to feel at least as happy (if not happier) than reading elating content slowly.

2.2 The Speed–Mood Link One of the more robust findings in research on thought speed is the positive mood-enhancing effect of fast thinking. We now review additional findings demonstrating the impact of thought speed on mood. Prior to recent experiments, the relation between thought speed and mood was suggested to us by scattered findings across varied disciplines. For example, studies have found that differences in the tempo of music are associated with inducing different mood states—for example, with faster tempo music more likely to be appraised as either happy or angry, and music with slow tempo more likely to be appraised as sad (Gagnon & Peretz, 2003; Webster & Weir, 2005; also, more recently, Khalfa, Roy, Rainville, Dalla Bella, & Peretz, 2008; Morton & Trehub, 2007; Schafer, Huron, Shanahan, & Sedlmeier, 2015). Studies of drug intake have found that drugs that induce a faster pace (“stimulant drugs”), ranging from amphetamines to caffeine, induce not only fast thinking but also Consequences of Thought Speed 175 elated mood (Asghar et al., 2003; Sax & Strakowski, 1998; Smit & Rogers, 2000; more recently, White, Lott, & de Wit, 2006). And it has long been known that racing thoughts are a common prodrome to the elation and euphoria of a manic episode (e.g., Goodwin & Jamison, 1990; Sims, 2002; more recently, Homish, Marshall, Dubovsky, & Leonard, 2013), whereas depressive episodes are associated not only with reduced positive affect but also with the slowing down of thought (American Psychiatric Association, 2013; Hickie et al., 1999; Kraepelin, 1921; Schwartz, Friedman, Lindsay, & Narrol, 1982; Teasdale,Fogarty,&Williams,1980). More recently, experimental work, primarily from our lab, has intro- duced a number of methods for successfully inducing faster and slower thinking—and demonstrated subsequent changes in mood. The methods of thought-speed induction that have been used to alter mood can be approximately divided into two categories: methods that entrain participants’ speed of thinking to predetermined fast or slow situations and methods that require participants to generate thoughts at different rates.

2.2.1 Induction of Thought Speed Through Paced External Stimuli The rate at which external stimuli are processed can be altered to induce faster or slower thinking. Auditory and visual stimuli such as sounds, images, videos, and text can be streamed at different rates. Timed readings are frequently used in thought-speed research. The speed at which people read can be altered in these manipulations by programming the presentation of words on a computer screen. At the beginning of the manipulation, participants are instructed to read sentences aloud as they stream across the screen, for example, Thank you for your participation. For the next part of this study, you will be reading sentences on your computer screen. You will be reading aloud and you will be recorded over the internet… From Yang, Friedman-Wheeler, and Pronin (2014) By reading aloud while keeping pace with stimuli, participants must process stimuli at a preset rate. Faster processing can be achieved by shortening the gap between the presentation of each letter and the following sentence, for example, 40 ms per letter, 320 ms between sentences (in Pronin & Wegner, 2006). The induction of fast thinking through timed reading methods increases postmanipulation positive mood (Chandler & Pronin, 2012; Rosser & Wright, 2016; Yang et al., 2014). The positive mood-boosting effect of fast thinking occurs independently of the content of what is read 176 Kaite Yang and Emily Pronin

(Pronin & Wegner, 2006), and effects of thought speed on mood can occur both when the thought content is more limited (repetitive) and when it is more expansive (variable) in scope (Rosser & Wright, 2016). Similar to timed reading manipulations, timed video manipulations effectively alter mood by changing subjective speed of thinking. Pronin et al. (2008, Experiment 5) constructed a thought-speed manipulation wherein participants narrated a video segment (played on mute) from I Love Lucy. Participants who were randomly assigned to the fast-speed condition narrated the episode as it streamed at eight times its normal rate (i.e., in 3 min). In the normal-speed condition, participants narrated a 3-min clip from the same episode, played at the original speed that it was broadcasted. In the slow condition, participants narrated a clip played at 70% of its original speed. Following the speed manipulation, participants indicated their subjective thought speed and reported positive and negative mood using the PANAS. Participants in the fast condition reported significantly higher perceived thought speed compared to those in the normal and slow conditions (who did not differ from each other). More importantly, participants in the fast condition reported significantly higher positive mood compared to participants in the normal condition (the difference between the fast and slow conditions did not reach significance).

2.2.2 Instructional and Self-generated Speed Inductions Thought-speed inductions can also alter mood states through properties of tasks and instructions. For example, brainstorming involves the generation of ideas by participants and can be used as a speed manipulation. In one experiment, participants were instructed to brainstorm possible “ways to make 1-year’s college tuition in a summer” in 10 min (Pronin et al., 2008, Experiment 1). In the fast condition, participants were instructed to think of as many ideas as possible. In the slow condition, participants were instructed to generate only what they considered to be good ideas. This meant that participants experienced themselves generating more ideas (regardless of quality) per unit of time in the fast condition, compared to the slow condition. The manipulation achieved the intended effects as a speed induction, with participants rating their perceived speed of thinking as faster in the fast brainstorming condition compared to the slow brainstorming condition. Moreover, participants in the fast condition indicated more positive mood following the speed manipulation, compared to participants in the slow condition. Consequences of Thought Speed 177

Similarly, making a series of decisions in a shorter amount of time creates a feeling of thinking at a faster rate, compared to making decisions in a longer time frame. Pronin and Ricci (2007) assigned participants to make a series of hypothetical investment decisions. In the rapid decision condition, participants were allowed 4 s to make an investment allocation decision between one of two companies (e.g., FedEx vs Jet-Blue; Google vs Exxon). In the slow decision condition, participants were allowed 35 s to make each decision. In the rapid decision condition, participants reported thinking faster and feeling more positive mood on the PANAS compared to participants in the slow decision condition. This speed-manipulation method can also be used in a listing task that does not require the evaluation of two choices. Pronin and Jacobs (2008) instructed participants to count integers to 100. In the fast condition, participants counted without a pause between numbers. In the slow condition, participants were instructed to count to 100, but to leave a pause of 10 s between each integer. Following the manipulation, participants completed the PANAS scale. Participants in the fast condition reported more positive mood compared to participants in the slow condition. Changing task features can also alter the speed of thought. In one experiment (Pronin et al., 2008, Experiment 3), allowing participants to plagiarize ideas that they had heard from others gave participants the feeling of racing thoughts about that problem—when compared to the feeling of participants who were not allowed to list any ideas that they had heard from others. Par- ticipants in the former group not only listed more ideas per unit of time compared to participants who were instructed to generate only ideas that they had not heard previously, but participants in the fast-thinking condition (those with freedom to plagiarize) reported greater positive affect compared to participants in the slow-thinking condition (those without freedom to plagiarize). In another experiment by Pronin et al. (2008, Experiment 4), participants were led to complete either easy word problems or harder word problems (e.g., generating words that rhyme with “mite” vs “speck”; words with two syllables vs four syllables). Participants in the easy (fast) condition experienced a quicker thought pace, and they reported more positive mood, compared to participants in the difficult (slow) condition. Similar effects were observed in a senior thesis experiment from 2006 by Shingleton (advised by Pronin), in which participants were asked to list items in a broad category (fast-thinking condition) vs a narrower subset of that category (slow-thinking condition). 178 Kaite Yang and Emily Pronin

3. MORE CONSEQUENCES OF THOUGHT SPEED

Initial experiments investigating the effects of thought speed were primarily focused on emotion, but continued research on thought speed has revealed a host of other consequences of manipulating the pace of human thought. We now review a number of these other consequences. These include effects of experimentally manipulated thought pace on behavior (e.g., risk-taking), self-perception (e.g., self-esteem), and creativity (e.g., problem-solving). After reviewing these wide-ranging effects, we will turn to a theoretical discussion of the nature of thought-speed effects. That two- part discussion will begin by differentiating thought speed from related constructs (Section 4), and then offer a theoretical account for the causal effects of changes in thought speed (Section 5).

3.1 Fast Thinking Increases Risk-Taking Risk-taking refers to engaging in behaviors that are potentially rewarding, but have a higher likelihood of causing harm, injury, or illness to oneself or others, relative to other behaviors of everyday life (Byrnes, Miller, & Schafer, 1999; Steinberg, 2007). For example, using drugs, engaging in unprotected sex, bungee-jumping, and driving over the speed limit are some instances of risky behaviors. The ability to take risks is not altogether detri- mental. In fact, the ability to take some risks may be evolutionarily advantageous (Wang, Zheng, Xuan, Chen, & Li, 2016). Imagine, for example, the inherent risks (and the potential rewards) of investing in the stock market, taking on a large student loan for medical school, or venturing outside of familiar territory to hunt for food. Because the consequences of risk- taking can be substantial—whether for good or ill—understanding the factors that impact risk-taking is of significance. From previous research, we know that individuals’ inclination to risk-taking is influenced by a host of factors, and interactions among them, including personality (e.g., Nicholson, Soane, Fenton-O’Creevy, & Willman, 2006; Zuckerman & Kuhlman, 2000), development of the frontal lobe and dopamine system during adolescence (e.g., Steinberg, 2007, 2008), brain structures (e.g., Ernst et al., 2002; Galvan, Hare, Voss, Glover, & Casey, 2006), and context (e.g., Gardner & Steinberg, 2005; Kahneman, Slovic, & Tversky, 1982). We now review experiments from our laboratory revealing that a feature of human thought—i.e., thought pace—also impacts the human tendency to take risks. Consequences of Thought Speed 179

In a series of experiments, Chandler and Pronin (2012) manipulated participants’ thought speed and examined effects on risk-taking. Experiment 1 involved a thought-speed induction manipulation that was similar to that of Pronin and Wegner (2006), except that the streaming text in Chandler and Pronin’s experiment involved neutral-content trivia rather than emotionally valenced content. For example, trivia statements included: “Oranges contain vitamin C”; “Europe is the only continent without deserts”; “A pilot light continually remains lit in a gas stove”; and “There is no twelve of dia- monds in a deck of cards.” Participants were instructed to read the statements aloud, keeping pace with the timed presentation of the text. Following the thought-speed induction, participants reported their thought speed, completed the Positive and Negative Affect Schedule (PANAS; Watson et al., 1988), and—most importantly—completed the Balloon Ana- logue Risk Task (“BART”; Lejuez et al., 2002). The BART is a behavioral measure of risk-taking wherein participants play a game in which they can earn small amounts of money by pumping air into a computer-animated balloon. Each pump of the balloon results in a small monetary reward for the participant. However, the balloon bursts after a random number of pumps. When the balloon bursts, the participant loses the money that was originally gained from the air pumps inflating the balloon and must begin the process anew. Thus, with each pump there is the chance to make more money—but also the risk of losing everything. The results of this balloon-pumping experiment demonstrated that elevated thought speed produced increased risk-taking. In the fast-thinking condition, participants reported not only more positive mood and faster thought speed compared to participants in the slow condition, but also displayed greater risk-taking behavior on the balloon-pumping task. In the fast- thinking condition, participants pumped the balloon significantly more times on each trial than did their counterparts in the slow-thinking condition (see Fig. 2A). Additionally, in the fast-thinking condition, participants experienced a greater number of popped balloons as a result of their increased risk-taking. In this particular experiment, the increased risk-taking induced by fast thinking was neither beneficial nor costly. Interestingly, participants in the two conditions did not differ significantly in how much money they earned on the BART, because the earnings lost by bursting balloons were offset by the earnings gained by pumping the unbursted balloons more times. Thus, participants in the fast condition made, on average, $11.98, whereas participants in the slow condition made, on average, $11.40, F<1. 180 Kaite Yang and Emily Pronin

A B 30 4

25 3 per trial per trial 20 behaviors 2 Intentions to engage in risky Intentions

Mean number Mean number of balloon pumps 15 1 Fast Slow Fast Medium Slow Thought-speed condition Thought-speed condition Fig. 2 (A) Risk-taking on the Balloon Analogue Risk Task and (B) intention to engage in risk-taking (via CARE Inventory) both as a function of thought-speed condition (based on Chandler & Pronin, 2012).

In a second experiment, Chandler and Pronin (2012) demonstrated the impact of thought speed on intentions to engage in consequential, real- world, risk-taking behaviors. In this experiment, the researchers manipulated thought speed using a novel manipulation. That manipulation involved watching scenes from one of three versions of the motion picture Baraka (Magidson & Fricke, 1992). The scenes in the videos were of live images from nature (e.g., snow-capped mountains, waterfalls, animals) and city- scapes (e.g., urban structures). The three versions differed based on the average shot length presented in each scene, such that participants in the condition designed to induce fast thinking would see a series of quick shots (or “takes”) of a scene, while those in the condition designed to induce slow thinking would see fewer shots—each of longer length—of that same scene (and those in the middle-speed condition were in between). The average shot length of each scene was 0.75 s in the fast condition, 1.5 s in the medium condition, and 3 s in the slow condition. Each speed condition was matched on content. Thus, for example, participants in the fast condition might see a waterfall scene in four different takes of 0.75 s each, whereas those in the slow condition would see the waterfall scene via a single 3 s take (and those in the medium condition would see two takes of 1.5 s each). Par- ticipants watched the version of the video to which they were assigned, and then completed measures of thought speed, mood, and risk-taking. The risk-taking measure was the Cognitive Appraisal of Risky Events inventory (CARE; Fromme, Katz, & Rivet, 1997). The CARE assesses participants’ intentions to act on risky behaviors, as well as their expectations about the Consequences of Thought Speed 181 consequences of engaging in those risky behaviors. Behaviors include activities such as having unprotected sex, heavy drinking, illicit drug use, down- hill skiing, and procrastination. Intentions to take risks on the CARE, and expectancies about taking those risks, are strongly predictive of engaging in future risk-taking behaviors (e.g., Fairlie et al., 2010; Katz, Fromme, & D’Amico, 2000; Nickoletti & Taussig, 2006; Telzer, Fuligni, Lieberman, & Galvan, 2013). Results demonstrated that fast thinking induced greater intentions to engage in consequential risk-taking behaviors, such as using illicit drugs and having unprotected sex. Participants reported the lowest intentions to engage in risky behaviors in the slow-thinking condition, and the highest intentions to engage in risky behaviors in the fast-thinking condition, with the middle-speed condition falling in the middle (see Fig. 2B). Interestingly, participants’ thought-speed conditions also predicted the likelihood of their perceiving negative consequences of the actions in the CARE inventory, such that faster thinking led to significantly less perceptions of the negative consequences. When entered in a mediation analysis, the perception of negative consequences mediated the relation between experimentally manipulated thought speed and intentions to engage in risky behaviors. Taken together, these speed and risk-taking experiments pose an intrigu- ing account of some behavioral implications of thought acceleration. First, fast thinking led to increased risk-taking behavior on a computer-simulated task compared to slow thinking. Faster thinking also led to increased willingness to engage in common risk-taking behaviors (e.g., substance use, gambling), relative to slower and moderately paced thinking. These findings provide evidence for the causal effect of thought acceleration on desire to engage in risks as well as actual risky behavior. Second, Experiment 2 uncov- ered a possible mechanism for the effect of fast thinking on risk-taking. The decreased perception that risky behaviors would result in negative consequences mediated the relation between thought speed and endorsement of risky behaviors.

3.2 Fast Thinking Increases Purchasing Interest Fast thinking may impact not only on willingness to take risks but also on a more general interest in goal attainment and the pursuit of rewarding behaviors. In a set of senior thesis experiments by Hudson Andrews (advised by J. Chandler and E. Pronin), effects of thought speed on consumer purchasing interest and behavior were examined (Andrews, 2011). Participants, who 182 Kaite Yang and Emily Pronin were 60 college undergraduates, read paced trivia statements for the thought-speed induction. They then looked over a list of items that one might want to purchase, including: Pantene shampoo, designer jeans, Panasonic camera, Tide detergent, Nike sneakers, etc. The list included items of both hedonic and utilitarian appeal. Results were as predicted: Participants in the condition designed to induce fast thinking reported thinking more quickly, and reported more positive mood, than did participants who were induced to think slowly. More importantly, compared with participants who were induced to think slowly, participants who were induced to think fast indicated significantly greater interest in purchasing the various items, t(58)¼2.37, P¼0.02. The full set of results is shown in Table 1. In a second experiment, participants were given the opportunity to purchase actual items in the laboratory. Consistent with the results of Experi- ment 1 indicating increased interest in purchasing after being induced to think fast, we predicted that participants induced to think quickly would be more likely to buy products than those induced to think slowly. After participants completed the thought-speed manipulation and our written measures, the experimenter told them that, “as an additional way of thanking you for your participation,” they could buy various products at the rate of $1 each. Because participants were paid in cash for their participation, all participants had the ability to purchase a number of these items if they so desired. The items, which were placed on the table in front of the participant (one of each item) were: Snickers bar, Reese’s peanut butter cup package, package of CVS Ibuprofen, Rolling Ball pen, Sharpie highlighter, travel-size Pantene conditioner, travel-size Pantene shampoo, Aveeno moisturizing lotion, Tide To Go stain remover stick, 5-Hour Energy bottle, and Celestial Seasonings Sleepytime tea box. Participants were provided with a plastic bag and left to make their selections. The result was that participants in the fast condition were significantly more likely to make a purchase compared to participants in the slow condition, X2 ¼4.69, P¼0.03. Indeed, a total of 50% of participants in the fast-thinking condition purchased at least one item, whereas only 23% of participants in the slow-thinking condition made a purchase. An experiment by Pronin (2011) found similar results in the context of financial investing rather than consumer purchasing. Making financial investments is an interesting domain because it involves purchasing (e.g., buying stocks) and it also involves more risk-taking than the typical purchase (e.g., of a bar of soap). Research on persuasion has shown robust effects of fast speech on purchasing intent, enhancing positive attitudes toward the speaker, interest in the message, and intentions to purchase products Consequences of Thought Speed 183

Table 1 Effects of Thought Speed on Product Purchasing Interest Thought Speed Fast Slow Tdf Can of Pepsi 2.80 (2.54) 2.63 (1.90) 0.29 58 Movado watch 2.57 (2.18) 1.83 (1.76) 1.43 58 Designer jeans 4.57 (2.51) 3.53 (1.83) 1.82 58 iPad 4.86 (2.47) 4.43 (2.34) 0.70 58 Louis Vuitton bag 1.67 (1.24) 2.03 (1.69) 0.96 58 Helicopter tour of NYC 3.60 (2.81) 3.17 (2.39) 0.64 58 Broadway show tickets 4.80 (2.61) 4.57 (2.03) 0.39 58 Burberry perfume/cologne 2.63 (2.15) 2.63 (2.25) 0.00 58 Sony flat screen TV 4.97 (2.80) 3.30 (2.09) 2.62* 58 Panasonic digital camera 3.60 (2.19) 3.23 (1.99) 0.70 58 Yoga mat 3.83 (2.57) 2.93 (2.26) 1.44 58 Ray-Ban sunglasses 5.43 (2.45) 4.30 (2.35) 1.83 58 Pantene shampoo 3.43 (2.13) 2.07 (1.11) 3.12** 58 Tide detergent 4.23 (3.02) 2.40 (1.71) 2.90** 58 Oral-B toothbrush 3.60 (2.14) 2.97 (2.41) 1.08 58 Tylenol 3.97 (2.36) 2.93 (2.10) 1.80 58 Encyclopedia Britannica 1.90 (1.56) 2.87 (2.40) 1.85 58 Dial liquid soap 2.63 (1.67) 2.33 (1.81) 0.67 58 Nike sneakers 5.77 (2.62) 4.97 (2.61) 1.19 58 North Face jacket 4.90 (2.80) 3.70 (2.25) 1.83 58 All products 3.79 (1.15) 3.14 (0.95) 2.37* 58

Note: *P<0.05, **P<0.01. Standard deviations appear in parentheses below means.

(e.g., Chebat, El Hedhli, Gelinas-Chebat, & Boivin, 2007; LaBarbera & MacLachlan, 1979; McCoy, Bedrosia, Hoag, & Johnson, 2007; Megehee, Dobie, & Grant, 2003; Smith & Shaffer, 1995). Given that financial investment decisions sometimes take place in the interpersonal context of speaking with a financial advisor, we aimed to test whether participants’ thought speed when contemplating investment decisions, as manipulated by a 184 Kaite Yang and Emily Pronin purported financial adviser’s rate of speech, would impact their interest in various financial investments. The experiment was conducted for the FINRA Investor Education Foundation, which aims to promote wise investing behavior. Participants were 80 adults at a New Jersey shopping mall (median age¼48, age range: 18–91). The experiment employed a var- iant on the paced reading manipulation of thought speed. Instead of reading paced text, participants heard an audio recording of an individual—allegedly a stock broker—describing seven potential investments that they might be interested in. The recording was warped using digital editing software so that the broker spoke either quickly or slowly (the warping was not noticeable, and the speech sounded smooth). The result was that participants not only felt more happy and energetic after listening to the fast-talking broker than the slow-talking one, but they also reported being inclined to invest more of their money. When participants considered making an investment of up to $10,000 in the opportunities they had just learned about, they wanted to invest $2763, on average, in those opportunities when the broker spoke slowly. When the broker spoke quickly, participants wanted to invest an average of $3567 in those same opportunities. Thought-speed effects on consumer behavior have been replicated in an independent laboratory (Duff & Faber, 2008; Duff & Sar, 2015). Duff and Sar (2015) designed a thought-speed manipulation using animated advertise- ments for various products (e.g., a camera). In the first experiment, participants viewed ad messages that streamed at a rate of 40 ms per letter for the fast animation condition and 160 ms per letter in the slow animation condition. Following the speed induction, participants were given a print ad from a magazine to browse. Compared to the slow animation condition, participants in the fast animation condition reported faster perceived thought speed, demonstrated increased physiological arousal, and indicated that they had greater intent to purchase an item from a print ad following the manipulation. Duff and Sar replicated the effect of fast thinking on intention to purchase products in a second experiment. In addition, they found that participants who viewed the fast animation reported more perceived energy, more positive mood—and also more negative mood—compared to participants who viewed the slow animation. In a third experiment, participants who viewed the fast animations were willing to spend more money and purchase more products for themselves (vs purchasing for others) after viewing an online advertisement for products from a department store. Participants in the slow animation condition did not differ on how much they were willing to buy for themselves vs others. Consequences of Thought Speed 185

The finding that the fast condition in Duff and Sar’s (2015) experiment elevated not only positive mood but also negative mood is worth noting. This finding is atypical in the thought-speed literature, but conceivable in the context of the experimenter’s animation manipulation, which may have produced some negative arousal. Duff and Sar (2015) found that their manipulation increased arousal, and it is quite possible that the speed of the manipulation induced not only excitement but also frustration and other negative arousal. It is important to note, though, that the effect of fast thinking on negative mood is not a robust effect, as shown by previous research demonstrating nonsignificant effects of speed on negative mood (e.g., Chandler & Pronin, 2012; Pronin & Wegner, 2006). Collectively, the experiments on thought speed and consumer behavior show evidence for goal-driven, appetitive effects of fast thinking. Corrob- orating research from the marketing and persuasion literature also highlights the consummatory consequences of fast thinking. Telemarketers who speak at a faster rate produce higher intention to purchase products and services (Chebat et al., 2007). Videotaped, acted scenarios of communication between a bookstore clerk and customers showed that participants had more positive attitudes toward the clerk when he delivered messages at a fast rate of speech, compared to a slow rate of speech (McCoy et al., 2007).

3.3 Fast Thinking Enhances Creative Insight Creative problem-solving is a prized ability, and one whose origins are not well understood. Studies have identified possible sources of creativity in stable features of the individual, such as self-confidence, openness, and risk- taking (e.g., Eysenck, 1993) and intellect (Sternberg, Lubart, Kaufman, & Pretz, 2005), as well as in features of an individual’s environment, such as birth order, mentoring, and political anarchy (e.g., Simonton, 2000). Mood, motivation, and mania have also been implicated in creativity (e.g., Amabile, 1982; Isen, 1999; Murray & Johnson, 2010). Here, we provide new evidence, jointly conducted by the authors of this chapter, that a transient aspect of individuals’ ongoing cognitive activity—i.e., the speed of their thinking—causally impacts creative insight and problem-solving. In our first experiment testing whether thought speed impacts creativity, we randomly assigned 89 participants from Mechanical Turk to either a fast thought-speed condition or a neutral thought-speed condition. In this experiment, we employed a neutral thought-speed condition, rather than a slow thought-speed condition, so that we could make more direct 186 Kaite Yang and Emily Pronin inferences about the impact of fast thinking on creativity (as opposed to being unable to infer whether any observed effects were due to the slow- speed manipulation). In both conditions, participants read aloud into an online voice recorder, keeping pace with trivia statements as they streamed in a YouTube video. Statements streamed at a rate of 40 ms per letter in the fast condition and 390 ms per letter in the neutral condition (see Yang et al., 2014). The presentation rate in the neutral condition was chosen based on its inducing participants to report a moderate pace of thought in previous research on MTurk (Yang et al., 2014). Following the speed induction, participants rated their thought speed, and then engaged in measures of two different types of creativity: insight creativity (or creative problem-solving) and generative creativity (or creation of artistic products). Insight creativity involves arriving at a novel and useful solution to a problem (Mednick, 1962; Schooler & Melcher, 1995). Arriv- ing at a novel solution is frequently accompanied by a sudden “aha!” moment and the inability to articulate the conscious processes that resulted in the attainment of the insightful solution (Bowden, Jung-Beeman, Fleck, & Kounios, 2005; H elie & Sun, 2010; Schooler & Melcher, 1995). On the other hand, generative creativity describes the creation of artistic products—e.g., visual, musical, literary (Amabile, 1982; Thys, Sabbe, & De Hert, 2014), which often requires persistence, skill, and practice over time (Amabile & Pillemer, 2012). The creative and artistic qualities of these works are determined by independent raters, who can range from experts in the relevant domain to college students without relevant formal training (Akinola & Mendes, 2008; Amabile, 1982; Griskevicius, Cialdini, & Kenrick, 2006). In order to assess insight creativity, we asked participants to complete 10 Remote Associates Test (RAT) problems (Mednick, 1962; more recently, Bowden & Jung-Beeman, 2003). For example, one problem was: cracker, fly, fighter, with the solution: fire. The RAT problems were selected from a bank of 144 RAT problems with data on difficulty and solution rate (Bowden & Jung-Beeman, 2003). Each of the 10 problems included in this experiment could be solved by 63%–82% of participants within 15 s. In Experiment 1, participants viewed one RAT problem per “page” of the online experiment. After 15 s, the page automatically proceeded to the next RAT problem. In order to assess generative creativity, participants were asked to write three brief poems and complete three story stems. For the poem task, participants wrote three cinquain poems (Amabile, 1982). Consequences of Thought Speed 187

Participants were presented with instructions describing the form of a cinquain poem, which consists of five lines (e.g., Line 1 is a single noun, Line 2 is two adjectives describing the noun). Then, participants were asked to write three cinquain poems with the noun for the first line provided in the experience (e.g., “Door” for the first poem, “Eyes” for the second poem, and “Life” for the third poem). For the story stem task, participants completed three sentence fragments in a creativity assessment adapted from Griskevicius et al. (2006). The sentence fragment was an ambiguous statement such as “It’s not the street I usually go down…” Participants were instructed to write a short five-line story based off of the first sentence stem. Participants’ poems and stories were rated on degree of creativity by a coder blind to speed condition. A random subset (20%) of the poems and stories was rated by a second coder (ICCs: 0.75 for poems, 0.79 for stories). As in previous experiments using paced reading, participants in the fast condition reported thinking significantly faster than participants in the neutral condition, t(87)¼4.70, P<0.001. Similar to previous experiments on MTurk, participants in the neutral condition rated their perceived thought speed close to the midpoint of the scale (M¼4.60, SD¼2.40). Codings of participants’ poems and stories, however, revealed that thought-speed condition did not significantly affect participants’ generative creativity. That is, those induced to think fast did not generate more creative poems and stories. Another story emerged, though, when it came to participants’ responses on the RAT, our measure of insight creativity. Participants in the condition where they were led to think fast scored higher on the RAT than did participants in the neutral-speed condition, t(87)¼2.18, P¼0.03. On average, participants in the neutral-speed condition solved 6.60 out of 10 problems, whereas those in the fast-speed condition solved 7.55 problems (Yang & Pronin, under review). In a second experiment, we aimed to test whether the effect of thought speed on creative insight would replicate. In this second experiment, which we conducted online, 318 participants were again induced to think at a fast or neutral speed by virtue of paced reading on their computer monitor. In order to assess insight creativity, participants were asked to complete the RAT of creative insight, as well as a second measure of creative insight. For this second measure, they completed nine “verbal insight problems.” The verbal insight problems consisted of word problems that required the use of creative problem-solving, such as inhibiting inappropriate responses and mental restructuring of the problem (DeYoung, Flanders, & Peterson, 2008; 188 Kaite Yang and Emily Pronin

Duncker, 1945). For example, one of the problems asked participants to think about the following scenario: A man in a town married 20 women. He and the women are still alive, and he has had no divorces or annulments. He is not a bigamist (meaning he is not legally married to more than one woman at once), and he broke no law. How is that possible? The answer to this problem is that the man was the officiant of the wedding ceremony. The insight process involves mentally restructuring the word “married” to mean conducting the rites of the wedding, not personally being married to each woman. Each verbal problem was presented individ- ually on a “page” of the online experiment. Each page was timed to proceed to the next problem after 2 min. Participants displayed greater insight creativity after being induced to think fast. Those in the fast-thinking condition solved more RAT problems than those in the neutral-speed condition, t(316)¼2.19, P¼0.03. In addition, those in the fast-thinking condition also succeeded in solving more verbal insight problems, t(316)¼3.91, P<0.001. See Fig. 3A and B for the average performance on insight creativity measures by speed condition in the second creativity experiment. Taken together, the findings from these two experiments suggest that fast thinking fosters the sorts of “aha moments” associated with creative insight. These findings point to the need for continued research on the effect of thought speed on creativity. Key challenges to this research area include dis- criminating between the types of creative ideation that would be sensitive to

A B Remote associates Verbal insight 9 9 8 8 7 7 6 6 5 5 4 4 Mean correct score 3 3 2 2 Neutral Fast Neutral Fast Fig. 3 Number of creative insight problems solved based on speed condition for (A) remote associates test problems and (B) verbal insight problems. Error bars indicate 1 SE above and below the mean. Consequences of Thought Speed 189 speed effects. Insight creativity, generative creativity, and divergent thinking each involve different cognitive processes and demands on attention (Smith & Blankenship, 1989; Thrash, Maruskin, Cassidy, Fryer, & Ryan, 2010). Although there is no magic bullet for inducing creativity, our results suggest that thought speed may be an easily manipulated variable that can elicit meaningful effects.

3.4 Fast Thinking Elevates Self-esteem Fast thinking involves distortions in perceptions and evaluations of the self. Experimental research on thought speed provides some evidence in support of the causal link between fast thinking and changes to self-perception. Pronin and Wegner (2006) found that participants in the fast conditions felt more powerful, strong, and creative compared to participants in the slow conditions. Participants were marginally more likely to display grandiosity (abnormally inflated self-esteem) in the fast conditions compared to the slow conditions, though there were no differences in self-esteem based on speed condition. In a series of experiments, Pronin et al. (2008) followed up on these results by examining speed effects on a number of self-perception measures. In Experiment 1, Pronin et al. (2008) used a brainstorming task to manipulate thought speed and measured self-esteem using the State Self- Esteem Scale (SSE; Heatherton & Polivy, 1991). State self-esteem measures individuals’ current self-evaluation. State self-esteem was significantly higher in the fast condition compared to the slow condition. In Experiment 2, which used a speed induction that altered the number of ideas that participants were exposed to, participants in the fast condition again reported significantly higher state self-esteem. Experiment 3 used an indirect speed manipulation wherein participants were exposed to ideas from a group brainstorming session and gave a verbal presentation of ideas to a different group (fast condition) or the original group (slow condition). For the fast condition, participants would be free to use any of the original group’s ideas as well as their own ideas in the presentation, thus increasing the number of ideas available to participants in a limited amount of time. Following this manipulation, there were no effects of speed on state self-esteem. However, participants in the fast condition felt more powerful and appeared more grandiose than participants in the normal-speed condition. In this experiment, raters blind to condition coded participants’ speeches and evaluated speeches from the fast condition as more grandiose than speeches from 190 Kaite Yang and Emily Pronin the normal-speed condition. In Experiment 4, experimenters altered thought speed with a listing task. Participants completed a series of word problems that either were simple enough to elicit quick responding and the feeling of fast thinking (e.g., list 12 words that end in “-ch”) or that elicited slower responding and the feeling of slower thinking (e.g., list 12 words that end in “-rch”). Participants in the fast condition indicated significantly higher state self-esteem and grandiosity compared to participants in the normal condition. There was a trend for participants in the fast condition to feel more powerful than their counterparts in the normal-speed condition, though this effect did not reach significance. Collectively, this set of experiments provides support for the effect of fast thinking on self- perception. Fast thinking was found to elevate postmanipulation self- esteem, perceived power, grandiosity, and the perceived significance of behaviors. However, some manipulations of thought speed were more suc- cessful than others in inducing changes on these variables. Clearly, the relation between thought speed and self-perception variables warrants further research. There may be specific manipulations and/or dependent measures that are more effective in demonstrating an elevated estimation of one’s self-worth and abilities following fast thinking. This point is illustrated in an experiment we conducted with dysphoric and non- dysphoric participants (see Yang et al., 2014), where self-esteem was assessed using the Beck Self-Esteem Scale (BSE; Beck, Brown, Steer, Kuyken, & Grisham, 2001). In this experiment, thought speed was manipulated by having participants read aloud timed trivia statements (e.g., “Oranges contain vitamin C”). We did not find an effect of the thought-speed manipulation on self-esteem in this experiment. There are at least two differences between this study and past research. First, the measure of self-esteem was different from the measure that has been used in previous research on the effects of fast and slow thinking (e.g., State Self-Esteem Scale). Second, the thought-speed manipulation was also different: in previous thought-speed manipulations that found some evidence for the effect of speed on self- perception variables, thought-speed stimuli approximated the emotional and cognitive content of “self-talk” or required participants to generate their own ideas (e.g., Pronin et al., 2008; Pronin & Wegner, 2006). It is possible that the “self-relevance” of stimuli interacts with the speed of thinking to produce changes in feelings of self-worth and power. It is worth noting that the tendency for fast thinking to induce inflated self-esteem is unlikely to be caused by any tendency for fast thinking to induce greater feelings of success at the relevant experimental task. Consequences of Thought Speed 191

A clear example of this point comes from Experiment 4 by Pronin et al. (2008). In that experiment, participants in the fast condition completed easier word problems than those in the slow condition. In the experiment, participants were asked to rate their success on the word problems. The fast thought-speed condition (which had the easier word problems) induced feelings of fast thinking and positive mood, but it did not impact perceived success at the problems and, therefore, perceived success could not have mediated the relation between thought speed and self-esteem.

3.5 Fast Thinking Is Arousing Fast thinking increases perceived energy and arousal. Across several experiments, we have found that when participants are induced to think fast, they report feeling more energy than when they are induced to think more slowly (Pronin & Wegner, 2006; Pronin et al., 2008, Experiments 1 and 2). Research from music studies, cognitive psychology, and neuropsychology strongly suggests that altering the subjective experience of speed affects physiological activation. For example, sympathetic arousal increases when listening to fast-paced music or beats (Khalfa et al., 2008). Experimental stress and threat inductions activate physiological responses that allow the body to spring to action (Engert et al., 2011). The psychophysiological activation during episodes of mania bears similarity to the psychophysiological activation under the influence of stimulant drugs such as amphetamines (Asghar et al., 2003). Interestingly, bipolar disorder may be characterized by disturbances in the amount of variability of sympathetic activity rather than simple differences in the average level of sympathetic activity. Gruber, Mennin, Fields, Purcell, and Murray (2015) found that relative to participants with depression and healthy controls, participants diagnosed with bipolar I disorder exhibited greater fluctuations in sympathetic arousal during a 6-day measurement period. However, the mean level of sympathetic arousal did not differ between the groups. Although there is some compelling evidence that tempo, behavioral activation, and arousal affect physiological responses, direct tests of the effects of thought speed on psychophysiological measures are needed. Duff and Sar (2015) found that exposure to fast animations of product messages increased physiological arousal, measured using electroencephalogram (EEG), compared to slow animations. The effects of dopamine may be a crucial com- ponent to the experience of thought speed. Past work has shown that the association between actions and pleasant outcomes (e.g., pressing a lever that 192 Kaite Yang and Emily Pronin causes a piece of food to be dispensed) is modulated by dopamine (Wise, 2004). Dopamine may modulate the experience of fast thinking that is accompanied by a pleasurable, rewarding experience of novel stimuli (in this case, each thought constitutes a novel stimulus for the brain). The learned association between fast thinking and appetitive motivation is perhaps facilitated by dopaminergic networks. Dopamine affects time perception and has been implicated in learning and memory of reward-driven, appetitive behaviors (Meck, 2005; Wise, 2004).

4. THOUGHT SPEED AND RELATED CONSTRUCTS

In this section, we review a number of constructs that seem related to thought speed and discuss those relations. These include fluency, System 1 thinking, and goal progress.

4.1 Speed and Fluency Thought speed bears some conceptual overlap with fluency, and the distinc- tion is therefore worth considering here. Fluency is a psychological construct that describes the ease with which stimuli can be processed. Fluent stimuli can consist of sentences presented in an easy-to-read font, prototyp- ical exemplars, flowing lines, familiar objects, continuity of speech, and high-contrast presentation of objects (Alter & Oppenheimer, 2009). Impor- tantly, fluent stimuli can be characterized by the fast processing speed that they engender (Winkielman, Schwarz, Fazendeiro, & Reber, 2003). Also, subjective evaluations of fluent stimuli are more positive, and a “warm glow” of positive affect can result (e.g., Monin, 2003; Winkielman et al., 2003), which is consistent with the positive mood effects engendered by fast thinking. Prior manipulations of thought speed have sometimes involved fluency. For example, Pronin et al. (2008) manipulated the ease of completing word tasks as a manipulation of thought speed. Participants in the fast-thinking condition completed “easy” word problems that they could solve quickly (e.g., listing words that rhyme with “mite”; listing words that end in “-ch”), whereas participants in the slow-thinking condition completed “hard” versions of these word problems (e.g., listing words that rhyme with “speck”; listing words that end in “-rch”). Participants in the fast condition reported thinking faster and scored higher on positive mood. Other manipulations of fast thinking, though, have involved exposure to less fluent stimuli, rather than more fluent stimuli. For example, in our I Love Lucy Consequences of Thought Speed 193 experiment (described earlier), participants verbally narrated a television program at either its normal speed or at a fast speed (eight times normal). Although the episode is clearly more difficult to process and comprehend at eight times normal speed, participants reported more positive affect in that condition. In a recent set of experiments in our laboratory, Jacobs and Pronin (2017) directly examined whether fluency could account for effects of fast thinking on mood. In Experiment 1, Princeton University undergraduates were randomly assigned to one of four possible conditions combining levels of high and low speed and fluency in a 22 design. In each condition, the participants read text that streamed across a computer screen, describing a series of ordinary events that unfolded during the course of a college student’s day. In the fluent conditions, each sentence of text contained a grammatically correct, easy to comprehend description of an event in the day (e.g., “I went to the bathroom to take a shower and brush my teeth”). In the disfluent conditions, the words in that sentence were scrambled in a way that made them more difficult to comprehend (e.g., “Bathroom I went my shower to brush and to the teeth take a”). In the fast conditions, the sentences streamed at a rate of 40 ms per letter. In the slow conditions, the sentences streamed at 170 ms per letter. The total reading time across the four versions of the manipulation was controlled by removing redundant sentences in the slow conditions. For example, the following excerpt in the fast/fluent condition was modified in the slow/fluent condition by removing the italicized sentences: I went to the bathroom to take a shower and brush my teeth. The warm water woke me up. I went back to my room and got dressed. Then I had a bowl of cereal. I also finished some reading I had left over from the night before. I left my room to go to Biology, my first class of the day. Jacobs and Pronin (2017) Following the manipulation, participants indicated posttest positive and negative mood, perceived thought speed, and perceived fluency. Results showed that participants in the fast conditions reported significantly faster thought speed compared to participants in the slow conditions. Participants in the fluent conditions reported significantly greater ease of processing compared to participants in the disfluent conditions. Controlling for pretest positive mood, there was a significant effect of thought-speed condition on posttest positive mood, F(1,55)¼7.13, P¼0.01 (see Fig. 4A). However, there was no effect of fluency on posttest positive mood and no interaction between speed and fluency. In other words, positive mood was higher in 194 Kaite Yang and Emily Pronin

A B 7 7 Fast thought speed Slow thought speed 6 6

5 5

4 4

3 3 Positive mood Positive mood

2 2

1 1 Low fluency High fluency Low fluency High fluency Fig. 4 Effects of thought speed and fluency on positive mood in Experiment 1 (A) and in Experiment 2 (B) (Jacobs & Pronin, 2017). conditions where fast thinking was induced, even when the content of sentences was scrambled in a disfluent manner. In addition, fast thinking did not increase fluency. Rather, fast conditions were associated with less fluency compared to slow conditions, indicating that subjective fluency also could not explain the effect of fast thinking on positive mood. In a second experiment, Jacobs and Pronin manipulated fluency by inter- jecting (into the text that participants read) common disfluencies found in everyday speech. In the low-fluency condition, participants again read a description of a college student’s day—but this time the description included expressions such as like, um, and uh (e.g., “My alarm, um, went off this, uh, morning at, like, eight o’clock.”). In the high-fluency condition, participants read the description without the speech disfluencies (and some sentences were added to equate for length without impacting meaning, coherence, or tone). The experiment manipulated thought speed using the same methods from Experiment 1, thus employing a 22 design with thought speed as one independent variable and fluency as the other independent variable. Results of this second experiment were consistent with the previous experiment: participants in the conditions designed to induce faster thinking reported more positive mood than did participants in the conditions designed to induce slower thinking (Ms¼5.03 vs 3.03), F(1,56)¼38.38, P<0.0001 (see Fig. 4B). Again, there was no main effect of fluency on mood and no interaction between fluency and speed. In addition, participants reported greater perceived fluency in the slow-thinking condition than in the fast-thinking condition, suggesting that subjective fluency could not account for the effect of fast thinking on positive mood. The findings Consequences of Thought Speed 195 here indicate that fast thinking and fluency are not the same construct. Alone, the fluency of stimuli does not affect perceived thought speed. More- over, perceived fluency may sometimes be higher when thought speed is slower, providing further evidence that the psychological consequences of fast thinking are not explained by fluency effects. A consideration of the relation between fluency and thought speed still raises interesting ideas and questions. For example, fluency generally is conceived as involving low-level processing, whereas fast thinking generally is conceived as involving higher order thinking. It is interesting to consider whether rapid thought speed at a lower level might engender similar effects to higher order fast thinking. Future research should investigate whether accelerations of lower level processing speed, such as reaction time or rapid visual processing, might elicit elevated mood and other consequences of fast thinking.

4.2 Speed and Dual Process Theories of Thinking The idea of “thinking fast” has been invoked in recent literature on judgment and decision-making. Daniel Kahneman’s best-selling book Thinking, Fast and Slow discusses research in judgment and decision-making that produces a compelling argument for dual process models of thinking (Chaiken, 1980; Kahneman, 2011). Kahneman’s delineation of two systems of thinking invokes the notion of speed. In System 1, thinking is automatic, effort- less, intuitive, and “fast.” Thinking in this system is often susceptible to bias and use of heuristics. System 2 describes thinking that is “slow.” This is the slowness of effort, in which thinking is principled, constructed intentionally, and follows a logical progression. An example would be employing logic to reason through a problem and arrive at the accurate conclusion. We suspect that there are differences between our conceptualization of thought speed and Kahneman’s identification of System 1 and System 2 thinking. Our conceptualization of thought speed involves thought rate—i.e., fast thinking in our conceptualization involves more thoughts per unit time. From our perspective, the experience of fast thinking might be exemplified by the experience of a flight of ideas in a great brainstorming session, an excited recounting of events during a particularly active day, or an episode of “racing thoughts” in mania. Slow thinking would describe thinking that is more sluggish, sleepy, and laborious, as in the experience of “writer’s block” or psychomotor slowing in depression. These experiences each involve perceived or actual increases or decreases in the number of 196 Kaite Yang and Emily Pronin thoughts per unit of time. This definition of thought speed can be differen- tiated from the “fast” and “slow” thinking of System 1 and System 2. Think- ing in System 1 may be fast insofar as it results in an attitude or a decision through a quicker process, but System 1 involves mental shortcuts, rather than more thoughts per unit of time. System 2 involves a more effortful, deliberate, and principled way of thinking, for example, hypothesis testing and solving logic problems. This results in a longer time to make a decision. However, it does not necessarily mean that there are fewer thoughts per unit time when engaging in System 2 processing. Although we are not currently aware of empirical research that distin- guishes between our conceptualization of thought speed and dual process theories of thinking, we can imagine that the two constructs can be differ- entiated in an experiment along the lines of Jacobs and Pronin’s experiments on fluency. A 22 experiment could be constructed, with thought speed and system of thinking as the independent variables.

4.3 Speed and Mental Progression A final construct worth considering is that of motivation and goal progress. A reader might wonder whether effects of fast thinking reflect the perception that one is closer to reaching one’s goal. For example, if I am thinking fast, might I be more likely to conclude that I am almost finished with my thought task, and therefore might I feel happier, more creative, and more self-assured? Mental progression describes the feeling that thinking is “going somewhere” (Mason & Bar, 2012). In other words, one has the sense that one is making progress toward a goal. This would be the opposite experience from rumination, where thoughts cycle repetitiously through a nar- row set of ideas (Nolen-Hoeksema & Morrow, 1993). Mason and Bar (2012) found that exposure to stimuli that progressed across different categories resulted in better mood compared to exposure stimuli that stagnated (all within the same category). Carver and Scheier (1990) proposed a model of goal attainment wherein affect is linked to the monitoring of progress toward goals. According to Carver and Scheier, individuals experience positive mood when they feel that they have spent less time than expected working toward goals. On the flip side, when individuals spend longer than expected on goal attainment, this leads to negative mood. The rate of acceleration or deceleration of goal attainment plays a role as well, in their model. One response to the question of whether thought-speed effects are actually caused by changes in perceptions of goal progress is that thought-speed Consequences of Thought Speed 197 manipulations often involve no sense of goal progress. For example, the use of long lists of trivia statements in speed manipulations produces effects on positive mood, risk-taking, and creativity (Chandler & Pronin, 2012; Yang et al., 2014). The trivia statements used in these experiments do not give participants a feeling of progression to a specific end, nor do the statements converge topically, but are instead randomly ordered (e.g., A pilot light continually remains lit in a gas stove; A sprinkler system protects a building against fire; In Ring Toss, players through a loop over a peg). Moreover, speed effects can occur even when the content of stimuli is repetitive (Rosser & Wright, 2016). In order to directly test whether fast thinking effects can occur independently of goal progress, Pronin and Jacobs (2008) conducted a simple experiment. Speed and goal pursuit were manipulated in a 22 design. Participants were instructed to count to 100. In the goal pursuit conditions, participants were given a clear target goal of counting to 100 four times. In the no-goal conditions, participants were told to keep counting until the experimenter instructed them to stop. In the fast conditions, participants were instructed to count without any pause between numbers. In the slow conditions, participants were instructed to count with a 10-s interval between each number that they counted. Results revealed a main effect of speed on mood, with fast thinking once again leading to more positive mood than slow thinking. There was no effect of goal pursuit on mood and no interaction between goal pursuit and speed.

5. HOW THOUGHT SPEED WORKS

Why does thought speed exert a wide range of effects on human emotion, judgment, and action? In this section, we present an adaptive theory of thought speed that aims to explain these relationships.

5.1 The Basic Idea The evidence we have reviewed concerning consequences of thought speed shows that fast thinking is associated with positive mood, heightened arousal (increased energy), high confidence, and increased tendencies toward both risk-taking and creative problem-solving. The particular constellation of effects that are induced by accelerated thought speed is coherent from an adaptive perspective. Taken together, the combination of positive mood, arousal, confidence, risk-taking, and creative problem-solving is a set of responses likely to be induced by and needed in circumstances posing an 198 Kaite Yang and Emily Pronin urgent need for action to ensure an individual’s survival and reproduction (Pronin, 2013). The adaptive theory posits that thought speed and this con- sequent constellation of effects, which might be termed an activated state, are naturally linked. In situations that involve increased demand, individuals benefit from a “call to action,” with increased energy, motivation, excitement, and action-oriented emotion. Interpreting a demanding situation as ripe with opportunity would likely lead to this state of activation with an eagerness to think and act quickly to attain desired goals and outcomes. These situations immediately induce racing thoughts, but they also require a positive emotional drive (in terms of both affect and energy), as well as confidence and a willingness to take risks, and even a capacity to engage in creative problem-solving. See Fig. 5 for a schematic illustration of this pathway. The appetitive motivation (behavioral activation system) results in actions that move a person toward a desired object or end (Gray, 1987). Interestingly, the failure of motivational systems to spur an individual to action after exposure to stressful and aversive situations (e.g., learned helplessness) has been identified as a key aspect of depression (Maier & Seligman, 1976). According to our adaptive theory, accelerating thoughts should produce increased behavioral activity and arousal, including positive mood, optimism, perceived energy, creativity, novelty-seeking, risk-taking, positive self-evaluation, and motivation to approach goals. The deceleration of thought speed should inhibit these psychological states. Rather, the deceleration of thinking should result in more negative mood, sadness, and inhibited activity. Certain situations within the environment necessitate faster thinking. For example, emergency situations likely require faster than usual rates of thinking and acting. Emergency preparedness literatures emphasize both speed and deliberate action in the event of a catastrophe (e.g., Fast, Weaver, Miller, & Ferrin, 2016; Lovett, Massone, Holmes, Hall, & Lopez, 2014).

Situation Interpretation Response

Fast environment Demand Mobilize for action (excitement, energy, (elicits fast thinking) Opportunity activation, risk- taking, etc.)

Fig. 5 An adaptive model of thought speed: from environment to action. Consequences of Thought Speed 199

This connection between fast thinking and emergencies calls to mind the activation of the “fight or flight” response that prepares the body for urgent, life-saving actions. Like the “fight or flight” response, the adaptive activation of fast thinking in demanding situations likely involves myriad cognitive, affective, and physiological processes (Pronin, 2013). However, the adaptive activation of fast thinking is arguably more general in scope. Fast thinking is likely adaptive for the stress response because it enables an individual to make a quick getaway or initiate effective actions to engage in the situation. Fast thinking is likely adaptive in nonemergency situations that involve a level of demand and opportunity, as well. The efficient identification of changes in one’s environment and sensitivity to novelty may be abilities that confer adaptive benefits (Eckart & Bunzeck, 2013). Examples of adaptive advantages of fast thinking in nonthreatening circumstances include quickly associating a reward with an action that likely caused the reward, rapidly processing novel locations and social situations in order to identify food, shelter, and allies, and generating multiple mental representations of ways to solve problems. States of positive mood and arousal have been linked to productive generation of ideas (Baas, De Dreu, & Nijstad, 2008; Martindale & Greenough, 1973). A speedy pursuit of rewards likely ensures the actual attainment of positive outcomes.

5.2 Dopamine What are the processes, cognitive and physiological, that explain the connection between fast thinking and motivation to spring to action? Firing of the dopaminergic system is likely to result from fast thinking. Situations involving fast thinking produce mental exposure to multiple novel stimuli in short order. The exposure to novel stimuli leads to increased levels of dopamine and increased firing of dopamine neurons, especially in areas of the brain associated with goal pursuit (e.g., Rebec, Christensen, Guerra, & Bardo, 1997). Increased activation of the dopaminergic system is consistent with the effects observed in response to fast thinking. Specifically, increased dopamine activity is associated with feelings of being rewarded, motivation to attain goals, and even an accelerated internal clock (Blackburn, Phillips, Jakubovic, & Fibiger, 1989; Buhusi & Meck, 2005; Kandel, Schwartz, Jessell, Siegelbaum, & Hudspeth, 2013). An accumulation of research on dopamine suggests that it is particularly important in modulating sensitivity to rewards and the coordination of learned behaviors that result in the attainment of rewards (Wise, 2004). The persistence of practiced, goal-directed behaviors that are associated with 200 Kaite Yang and Emily Pronin reward-seeking and attainment is facilitated by dopamine (Packard, Cahill, & McGaugh, 1994). The ability to predict rewards and learn and exe- cute behaviors that result in maximally rewarding outcomes is modulated by dopamine, as demonstrated in experiments with dopamine-enhancing or - inhibiting substances (Pessiglione, Seymour, Flandin, Dolan, & Frith, 2006). Dopamine is also closely associated with the addictive effects of stimulant drugs, such as cocaine, but less closely involved in addiction pathways for nonstimulant drugs such as alcohol (Wise, 1988). In addition to facilitating appetitive and consummatory behaviors, especially in the case of learned behaviors that aid in goal attainment, dopamine has also been implicated more directly in the experience of thought speed. Eckart and Bunzeck (2013) conducted a randomized, double-blind, placebo-controlled experiment wherein participants received a precursor to dopamine, a cholinergic inhibitor, or a placebo. Participants were exposed to a series of pictures and tested for sensitivity to novel stimuli, processing speed, and memory. The group that received the dopamine precursor exhibited increased processing speed for all stimuli, including novel stimuli, relative to the placebo control and the cholinergic inhibitor groups (Eckart & Bunzeck, 2013). Research from Warren Meck and his colleagues has shed light on the functions of dopamine on internal timing. An organism’s internal timing, or “clock speed” refers to its sense of the duration of time on a task. For example, animals that are trained to press a lever to receive a reward following a particular schedule respond according to intervals of time that correspond to the schedule. An animal can be conditioned to associate a light that turns on every 18 s with engaging in a behavior that elicits a reward. Every 18 s, a light turns on, a lever is lowered, and pressing the lever results in the delivery of a reward (e.g., Meck, 2007). During test periods, the timing and the frequency of engaging in the rewarding behavior in the absence of reward can be measured. During testing phases, experimenters can admin- ister drugs that alter dopamine levels in the brain and then measure subsequent time perception on the task. Stimulant drugs such as cocaine and methamphetamine are dopamine agonists that amplify the amount of dopamine available in synapses. Dopamine antagonists such as haloperidol inter- fere with the binding of dopamine to postsynaptic receptors. Dopamine agonists (methamphetamine or cocaine) administered in rodents resulted in a faster internal clock speed. Rodents administered methamphetamine or cocaine exhibited reward-driven behavior faster than the rate set by the training procedure (Heilbronner & Meck, 2014). In addition, the speed Consequences of Thought Speed 201 effects of dopamine agonists were accompanied by increased impulsivity on a behavioral task. When fluoxetine (e.g., Prozac), a drug that alters the reup- take of serotonin, was administered, rats exhibited decreased impulsivity, but no differences in clock speed. Similar effects of dopamine agonists have been observed in humans, as well. When D-amphetamine was administered to humans, clock speed increased. On the other hand, when participants received haloperidol, clock speed decreased (Lake & Meck, 2012).

5.3 Embodiment and Entrainment The effects of entrainment and embodiment may also help explain why thought-speed manipulations work. Entrainment describes the tendency for physiological arousal and psychological processing to become synchronized with external tempo. Temporal processes of the human body (e.g., respiration rate, heart rate, muscular contractions) can become synchronized with the speed of external stimuli. For example, in an experiment by Khalfa et al. (2008), participants reported more arousal and displayed greater respiration rate in response to fast music in major key and also in response to beat-only fast tempo music (with no musical tones) as compared to slow music in minor key and also beat-only slow tempo music (with no musical tones). Participants’ blood pressure, zygomatic activity, and electrodermic response all decreased (and their corrugator activity increased) after listening to fast music in major key compared to slow music in minor key, though these results are difficult to interpret because of the conflation of musical tempo with musical key. Other experiments on entrainment have found that physiological arousal, as measured by EEG recordings, increased after fast- speed induction compared to slow-speed induction (Duff & Sar, 2015; Trochidis & Bigand, 2013). In terms of our research on thought speed, experiments concerning entrainment suggest that fast-paced external stimuli, such as rapidly streaming text, are likely to induce internal psychological responses that are synchronous with that fast pace, thereby inducing responses such as fast thinking and arousal. The manipulation of thought speed may also induce emotional and cognitive effects due to embodiment. Embodiment describes the priming of schema by engaging in stereotypical behaviors and action sequences. Research studies on facial feedback, misattribution, and embodiment have pointed to the possibility that inducing the experience of an aspect of a particular mental state activates the entire experience of that mental state. This may occur through the priming of schema, the activation of efferent 202 Kaite Yang and Emily Pronin neurons, or the attempt to make sense of physiological changes. According to Bargh, Chen, and Burrows (1996), embodiment effects may occur through what William James described as “ideomotor action.” When people imagine performing a behavior, or think about the context in which certain behaviors are performed, a mental representation of the behavior is activated. In this preparatory state, conscious or unconscious, courses of actions and possible outcomes may all be modeled in the mind prior to the inception of behavior. For the relation between thinking and behaving, the causal flow may be reversed, as well. There is a substantial body of literature in psychology that supports the idea that enacting a set of behaviors can induce mental representations and emotional states that correspond with how the behavior is typically experienced (e.g., Davis, Senghas, & Ochsner, 2009; Mussweiler, 2006; Soussignan, 2002). Thus, when people are induced to think quickly— for example, by engaging in the action of fast-paced reading, this may activate the arousing and energizing emotional state that is usually associated with situations that require fast thinking.

6. THOUGHT SPEED AND TREATMENT FOR DEPRESSION

Depressive disorders are mood disorders that are characterized by anhedonia, the loss of interest in activities that were once pleasurable, feelings of sadness, worthlessness, loss of energy, loss of motivation, and physiological symptoms such as disruptions of sleep and appetite (DSM-5, American Psychiatric Association, 2013). In the 1960s, Beck’s Cognitive Theory of Depression (e.g., Beck, 1963) revolutionized the conceptualization and the treatment of depression. Beck identified regular distortions in thought content that characterized and maintained depression. The impor- tance of cognition in depression continued to be emphasized in research on rumination as a trait-like predictor of depression (Nolen-Hoeksema, 2000). Rumination and distraction describe two opposing ways of processing negative events. When one engages in rumination, thoughts go down a “rabbit hole,” and emotions, reactions, and their consequences are continuously processed. Ruminative processing is consistently correlated with greater risk for depression and more severe symptoms of depression, and treatments thus have aimed to reduce rumination and correct cognitive biases (Beck, Rush, Shaw, & Emery, 1979; Brewin et al., 2009; Lo, Ho, Yu, & Siu, 2014; McGinn, 2000). Thus, considering the speed of cognition in treating depression continues the legacy of examining the cognitive dimensions of depression and seeking to affect those dimensions as a mode of treatment. Consequences of Thought Speed 203

Sluggish thought speed has long been identified in the symptom profile of depression. Roughly a century ago, Kraepelin (1921, p. 75) described the thoughts of people with depression as “paralyzed” or “immobile,” and Wells (1922, p. 538) wrote that “often absolutely nothing occurs to the patient.” When a person experiences an episode of clinical depression, his or her thoughts can become so sluggish that they can even feel as though they have come to a halt (e.g., Ianzito, Cadoret, & Pugh, 1974; Judd, Rapaport, Paulus, & Brown, 1994; Philipp, Maier, & Delmo, 1991). Empirical studies have shown that depressed individuals experience disruptions in cognition in domains such as working memory and processing speed (e.g., Hubbard et al., 2016; Schwartz et al., 1982). In a new research program, we have begun to investigate whether accelerating the thought pace of individuals experiencing depression might help to alleviate at least some of their symptoms. This idea is motivated by three pieces of knowledge: (1) fast thinking boosts positive mood, energy, and self-esteem (all of which are lacking in a depressive episode); (2) depressive episodes are characterized by deficits in thought speed; and (3) intervening in the cognitive process of individuals experiencing depression can alleviate their symptoms. Also, there is one extant study supporting this idea. In a (1978) paper, Teasdale and Rezin report asking clinically depressed individuals to repeat aloud letters from the alphabet. The letters (either A, B, C, or D) were presented in a randomized order, with a letter appearing every 1, 2, or 4 s. The result was that the more quickly participants were induced to repeat the letters, the more of a reduction in depressed mood they experienced.

6.1 Direct Experimental Tests In our first experiments investigating the effect of fast thinking on depressed individuals, we (Yang et al., 2014) predicted that fast thinking would improve positive mood for individuals experiencing symptoms of depression. In Experiment 1, we first administered a Beck Depression Inventory-II (BDI-II; Beck, Steer, & Brown, 1996) prescreen to 866 participants on Amazon.com’s Mechanical Turk crowdsourcing website. Par- ticipants were English-speaking residents of the United States. From this sample, participants who scored 12 or above on the BDI-II were invited via e-mail to participate in the experiment. To recruit a control group of nondepressed participants, we randomly selected a subset of participants who scored <12 on the BDI. A final sample of 128 participants completed 204 Kaite Yang and Emily Pronin the thought speed and mood experiment. Of this sample, 35 participants reported mild to moderate depressive symptoms, and 15 reported severe depressive symptoms (BDI-II29), whereas 78 participants were in the nondepressive group, having reported no depressive symptoms or minimal symptoms in the initial prescreen. Once in the experiment, participants completed pretest measures of positive and negative affect (PANAS; Watson et al., 1988) and depressive symptoms using the Center for Epidemiological Studies–Depression scale (CES-D; Radloff, 1977). Then, participants were randomly assigned to one of two thought-speed inductions. In the fast condition, participants viewed a YouTube video containing trivia statements that screened at a preset rate of 40 ms per letter with 500-ms intervals between sentences. In the neutral/moderate speed condition, each sentence streamed at a rate of 390 ms per letter with 1000-ms intervals between sentences. For ethical reasons, we did not include a slow condition. The total duration of the speed induction, fast or moderate, was less than 3 min. To ensure that participants complied with the speed induction, participants were instructed to make, and submit via the Internet, a voice recording of themselves reading aloud the statements. Following the speed induction, participants completed posttest measures of subjective thought speed (single-item speed measure; Pronin & Wegner, 2006), positive and negative affect (PANAS), and depressive symptoms (CES-D). Moderately depressive participants reported that their subjective thought speed was significantly faster in the fast condition compared to the neutral/moderate condition. Moreover, moderately depressive participants reported greater positive affect in the fast condition relative to the neutral condition, controlling for baseline positive affect, F(1,32)¼6.30, P¼0.02. These effects on subjective thought speed and positive mood also emerged for the nondepressive patients (consistent with previous research). The severely depressive participants, however, did not report a boost in thought speed after the fast condition and showed no significant mood effect (P>0.20). (See Fig. 6 for the estimated marginal means of posttest positive mood by speed condition and depression status.) Follow-up analyses showed that thought-speed condition had no effect on negative affect or on CES-D depressive symptoms for any of the three participant groups. We replicated thought-speed effects on positive mood in a second experiment with 196 nondepressive, moderately depressive, and severely depressive participants on MTurk. In this experiment, we used a rigorous method to contact participants immediately after screening to ensure that any Consequences of Thought Speed 205

B A Neutral 5 5 Fast 4.5 4.5 ** * n.s. * * n.s. 4 4

3.5 3.5

3 3

2.5 2.5 Positive mood 2 2 Posttest positive mood Posttest positive 1.5 1.5

1 1 None/minimal Mild/moderate Severe None/minimal Mild/moderate Severe symptoms symptoms symptoms symptoms symptoms symptoms Fig. 6 Fast thinking enhances posttest positive mood (controlling for pretest positive mood) for participants with no depressive symptoms and symptoms of mild to moderate depression, but not for participants with symptoms of severe depression, in Exper- iment 1 (A) and Experiment 2 (B) (based on data from Yang et al., 2014). depressive symptoms would not have abated by the time participants initi- ated the actual experiment. During the experiment, participants reported pretest positive and negative affect (PANAS), self-esteem (Beck Self-Esteem Scale; Beck et al., 2001), and depressive symptoms using the Physician Health Questionnaire (PHQ; Kroenke, Spitzer, & Williams, 2001). Follow- ing the manipulation, they completed these measures again. As in Experi- ment 1, the thought-speed manipulation elevated reports of thought speed for participants whose BDI scores were consistent with moderate depression (and for nondepressive participants), but not for those whose BDI scores were consistent with severe depression. And, as in Experiment 1, the fast-thinking condition led participants with moderate depressive symptoms to report increased positive affect. Again, consistent with Exper- iment 1, this positive mood boost was also found for nondepressed participants, but not for those whose BDI scores suggested severely depressive symptoms. There also was no effect of thought-speed condition on negative affect for participants with moderate or severe depressive symptoms, though the nondepressive participants indicated higher negative affect in the fast condition. There were no speed effects on self-esteem or depressive symptoms for any of the participant groups. In a recent experiment, Stoddard (2015) tested a novel thought-speed manipulation using a sample of women with subclinical depression. Partic- ipants aged 50–69 were recruited based on a score of 14 on the PHQ-9 (Kroenke et al., 2001), which corresponds with depressive symptoms in 206 Kaite Yang and Emily Pronin the minimal to moderate range. Thought speed was manipulated with a writing task. In the fast-thinking condition, participants were instructed to write as fast as possible for 10 min on a blank sheet of paper about any topic. In the control (normal speed) condition, participants were instructed to copy, at a leisurely pace, an article that experimenters provided. Perceived thought speed, positive and negative mood (PANAS-X with additional mood items), depressive symptoms (Zung Self-Rating Depression Scale; Zung, 1965), and physiological arousal were measured before and after the manipulation. In this experiment, participants did not report greater posttest positive mood (relative to pretest) in the fast-thinking condition compared to the neutral-speed condition, but they did report less depressive symptoms and reduced negative mood following the fast-thinking manipulation. Results for physiological arousal were mixed, with some markers indicating that fast thinking enhanced a positive sympathetic response (e.g., increased heart rate variability) and other markers indicating a stress response (e.g., decreased temperature, increased electrodermal response). Taken together, these experiments provide some promising evidence that supports further investigations to test thought-speed manipulations as a route to supplementing treatments for depression, particularly among individuals experiencing mild to moderate symptoms of depression. We note, however, that the effect of fast-thinking inductions has been measured only immediately following those inductions, and thus, we cannot assess the duration of the beneficial responses. Clearly, more research is needed to establish both the duration of the speed effect and whether repeated expo- sures to fast-thinking inductions (e.g., several times a week for 2 months) could improve depressive symptoms over time. Severely depressive participants were not responsive to the thought-speed manipulations. It is possible that they were already experiencing psychomotor slowing or impairments in processing speed that made the induction as it was presented not suitable for them.

6.2 Bipolar Disorder Bipolar disorders are mood disorders that are characterized by extreme fluctuations between positive and negative mood states. In particular, bipolar I disorder is defined by the presence of alternations between periods of intense positive mood, elation, and energy (mania) and periods of depression (DSM-5, American Psychiatric Association, 2013). Manic phases consist of disturbances in affect, cognition, physiological arousal, and behavior. Consequences of Thought Speed 207

Hallmark symptoms of a manic episode include the feeling of euphoria and positive affect; heightened energy and arousal (and decreased need for sleep); increased risk-taking; grandiosity (i.e., inflated self-esteem); irritability; motivation to pursue rewards; increased buying and spending; and heightened creativity (DSM-5, American Psychiatric Association, 2013; Andreasen, 1987; Di Nicola et al., 2010; Goodwin & Jamison, 1990; Gruber, 2011; Jamison, 1989; Johnson, 2000; Mansell & Pedley, 2008; Meyer, Beevers, & Johnson, 2004; Murray & Johnson, 2010; Schuldberg, 1990). Notably, the long list of symptoms of a manic episode bears a remarkable resemblance to the list of responses engendered by manipulations that induce fast thinking (Pronin, 2013; Pronin & Wegner, 2006). This resemblance raises questions for future thought-speed research. Given that thought speed is a common prodrome of a manic episode (indeed, more common than euphoric affect; e.g., Goodwin & Jamison, 1990), might alterations of thought pace play a causal role in the onset of a manic episode? Might manipulations that slow thought pace be able to play a role in preventing the onset of a manic episode? The latter question is one we believe worthy of experimental investigation.

7. METHODS OF MANIPULATING THOUGHT SPEED

Thought speed has been successfully manipulated using various methods. Below, we outline major categories of speed manipulations, including direct (e.g., timed stimuli) and indirect manipulations with substantial evidence to support their effectiveness as speed manipulations (e.g., time pressure, sympathetic arousal). Table 2 displays speed induction techniques that have been used in experimental research.

7.1 Rapidly Presented Stimuli One form of direct speed induction is the cognitive entrainment on external stimuli that stream at predetermined rates. This form of speed manipulation involves participants’ exposure to stimuli that are presented at specific speeds. The stimuli used in this form of speed manipulation have been primarily written, though both visual images and auditory stimuli have also been tested and shown to demonstrate similar effects (e.g., Chandler & Pronin, 2012; Pronin, 2011). Whether the induction is written (e.g., text presented at a rapid speed), visual (e.g., images presented at a fast speed), or auditory (e.g., speech presented at a rapid speed), the relevant stimuli Table 2 Methods of Manipulating Thought Speed Speed Induction Method Procedure References Pharmacological Administration of Asghar et al. (2003) amphetamines and stimulants Physiological Sympathetic arousal Mata et al. (2012) (e.g., elevation of heart rate, respiration) Paced reading Keep pace with Chandler and Pronin (2012), Duff computer-presented and Sar (2015), Pronin et al. (2008) paced text (Experiment 2), Pronin and Wegner (2006), Rosser and Wright (2016), and Yang et al. (2014) Twitter Read dense (“Twitter- Molouki and Pronin (in preparation) style”) text vs more traditional (“airy”) text Warped audio Listen to fast vs slow Kallinen and Ravaja (2005) and speech Pronin (2011) Musical tempo Listen to music or Khalfa et al. (2008) and Trochidis rhythms at different tempi and Bigand (2013) Average shot Watch film clip with short Lang, Zhou, Schwartz, Bolls, and length vs long average shot Potter (2000) and Chandler and length Pronin (2012) Warped video View video stimuli that Pronin et al. (2008) proceed at sped-up (warped) vs normal pace Plagiarizing Generate original text vs Pronin et al. (2008) and Stoddard plagiarize (2015) Brainstorming List all solutions to Pronin et al. (2008) (Experiment 1) problem vs viable ones Word problems Do easy vs less easy Pronin et al. (2008) (Experiment 4) problems Decision- Make choice every 4 s vs Pronin and Ricci (2007) making every 35 s Counting Count at a fast vs slow Pronin and Jacobs (2008) upward pace Category listing List members of big vs Shingleton (unpublished senior small category thesis) Time pressure Vary amount of time Ariely, Ockenfels, and Roth (2005) allotted to complete a task Temporal Induce perception that Sackett, Meyvis, Nelson, Converse, perception time flew by or dragged and Sackett (2010) on Consequences of Thought Speed 209 can be carefully controlled, such that presentation is at predetermined rates using simple tools such as Microsoft PowerPoint and YouTube for pre- senting the stimuli, and basic video and sound editing software for producing the stimuli. For example, Yang et al. (2014) used YouTube videos of PowerPoint slides that streamed sentences at fast and neutral rates. The sentences were comprised of affect-neutral trivia statements, such as “oranges contain vitamin C” and “Europe is the only continent without deserts.” The speed of presentation was determined by pilot testing to assess average reading speed in the participant sample. Participants were instructed to read aloud (and submit an online voice recording), in order to ensure that they kept pace with speed manipulation. The content and variability of external speed stimuli can be adjusted, as well. Pronin and Wegner (2006) used timed presentations of progressively more depressing or progressively more elated statements (Velten, 1968). Participants were instructed to read each statement aloud, keeping pace with the timed presentation of the statements. Rosser and Wright (2016) used affect-neutral trivia statements, but altered the variability of the stimuli so that participants read all distinct statements or read the same three statements repeated multiple times over the course of the speed induction.

7.2 Speed-Inducing Cognitive Activities Beyond entrainment to the pace of external stimuli, thought speed can be manipulated by changing the parameters and demands of cognitive tasks. Fast and slow thinking can be self-generated. Pronin et al. (2008) induced fast and slow thinking using various cognitive activities that involved the generation of ideas. For example, brainstorming was used as a speed induction by instructing participants to generate any ideas that come to mind without censoring themselves (fast condition) vs to carefully think through the problem and generate only good solutions (slow condition). Subsequent reports of subjective thought speed confirmed that participants indeed felt that their thoughts were going faster in the standard brainstorming condition compared to the compar- ison idea-generation condition (Pronin et al., 2008). Another example of a cognitive task that can generate different thought speeds involves having participants solve easy vs more difficult word problems (Pronin et al., 2008).

7.3 Musical Tempo Similar to the timed presentation of words and images, musical and rhythmic stimuli have been used to induce the psychological effects associated with 210 Kaite Yang and Emily Pronin fast and slow thinking. Auditory stimuli can be presented as beats that tap out a fast or a slow tempo (Khalfa et al., 2008). It is more common, however, for tempo to be paired with musical tone and variation. Participants are more likely to report positive emotions and arousal in response to music in a major key and fast tempo (Khalfa et al., 2008; Morton & Trehub, 2007). Negative emotions and sadness are more commonly associated with music in a minor key proceeding at a slow tempo (Trochidis & Bigand, 2013). Although there is substantial evidence that tempo fluctuations in music produce effects on mood and arousal that corroborate evidence from direct manipulations of thought speed, we recommend musical thought-speed inductions include a manipulation check for perceived thought speed.

7.4 Pharmacological and Physiological Alterations Chemically and physically induced variations in thought speed may be the most commonly experienced speed manipulations in everyday life. The consumption of caffeine may be an everyday fast speed induction that many take for granted. Placebo-controlled studies have found that stimulant drugs such as caffeine and amphetamines not only increase processing speed but also increase sympathetic arousal and can elevate positive mood, perceived energy, alertness, and novelty-seeking (Childs & de Wit, 2006; Durlach et al., 2002; Kirkpatrick et al., 2016; Sax & Strakowski, 1998; Smith, 2002; Vollm et al., 2004; White et al., 2006). Interestingly, after administration of methamphetamine or cocaine, rats exhibited increased clock speed (a measure of internal time estimation) and increased impulsivity (Heilbronner & Meck, 2014). Likewise, aerobic exercise that increases sympathetic nervous system arousal and exposure to rapidly moving stimuli (e.g., speed setting on a treadmill) may be considered a form of self-induced thought-speed alteration. Exercise has been shown to increase cognitive processing speed (Brisswalter, Collardeau, & Rene, 2002; Yagi, Coburn, Estes, & Arruda, 1999). Aerobic exercise directly alters the speed of heart rate, respiration, and movements of the skeletomuscular system. A substantial body of research supports the positive mood-boosting effects of exercise and the use of exercise as a treatment for depressive symptoms (for meta-analysis, see Mata et al., 2012; Mead et al., 2009; Rethorst, Wipfli, & Landers, 2009).

7.5 Time Perception The progression, duration, and enjoyment of time may be properties of experience that affect thought speed. The progression of thoughts in a Consequences of Thought Speed 211 logical, expansive manner produces more positive emotions compared to the feeling that thoughts are stuck in a stagnant cycle (Mason & Bar, 2012). Time pressure, which involves allotting a long time vs a short time for a task, may induce participants to think faster or slower. Time pressure increases the riskiness of decisions (Ariely et al., 2005). However, time pressure is an imperfect manipulation of thought speed, because it induces more aversive experiences such as agitation, negative mood, anxiety, and burnout (Glowinkowski & Cooper, 1987; Teuchmann, Totterdell, & Parker, 1999). On the other hand, the subjective feeling that time progressed faster than expected can lead to more positive reactions. One experiment manipulated the experience of time progression by telling some participants that they had spent 5 min on a task, when, in reality, they had worked on the task for 10 min, whereas other participants were told that they had spent twice as long on the task (Sackett et al., 2010). When participants were led to believe that time passed more quickly than it actually did, participants reported the task as being more enjoyable. It would be interesting for future research to examine whether distortions in time perception can in fact induce a posthoc impression of fast thinking, and whether that posthoc feeling, in turn, induces consequences of fast thinking.

8. SOME FUTURE DIRECTIONS FOR THOUGHT-SPEED RESEARCH

The adaptive theory of thought speed provides a framework for predicting the varied consequences of accelerating and decelerating thought speed. Some key causal relations in this theory have been tested, including the effects of thought speed on mood and risk-taking. However, as elabo- rated below, several key relations predicted by the model need to be further explored through empirical research.

8.1 Thought Speed and Psychophysiology The adaptive theory of thought speed predicts that accelerating thought speed stimulates psychophysiological activity that enables action and arousal, whereas decelerating thought speed should reduce activity and arousal. There is some empirical evidence to support this prediction: researchers have found increased activity of the sympathetic nervous system following fast thinking induction, but not slow thinking induction (Kallinen & Ravaja, 2005; Stoddard, 2015). There is also corroborating evidence from multiple disciplines to suggest that increasing the subjective experience of speed 212 Kaite Yang and Emily Pronin should affect physiological arousal (see Section 3.5 on fast thinking and arousal). Fast thinking also increases arousal as measured by EEG (Duff & Sar, 2015). Future research should continue to examine physiological responses to fast and slow thinking. Physiological arousal may mediate the relation between fast thinking and behavioral activation (e.g., problem- solving, risk-taking, consumption). More research is also needed to clarify the relation between thought speed and dopaminergic networks of the brain. Does the experience of fast thinking activate networks that modulate reward-sensitivity?

8.2 Thought Speed and Cognition A key assumption of our theory is that fast thinking can be adaptive under specific circumstances. We would predict that the ability to lock in and focus on novel or potentially threatening stimuli that emerge at a fast rate would be useful for survival. This could be manifested in the ability to quickly detect a predator or a dangerous situation and to enact a sequence of behaviors to avoid a harmful predicament. Alternatively, the ability to quickly detect and act upon rewarding stimuli would be evolutionarily advantageous, as well. Both situations necessitate an ability to quickly simulate or model courses of actions and their consequences and to determine the most effective present behavior. When conscious, intentional, and effortful screening of alternatives is not possible, fast thinking may continue to dominate the selection of automatic, intuitive, and familiar responses. How does the alteration of perceived thought speed affect cognitive processes that support decision-making? The acceleration and deceleration of thought may itself be a manipulation of processing speed. Although this idea seems likely, empirical research should be conducted to confirm that thought-speed manipulations affect processing speed in domains such as psychomotor speed, decision speed, and perceptual speed. Experiments should examine whether thought-speed manipulations affect reaction time, stimulus detection, inhibition, response accuracy, and working memory.

8.3 Thought Speed and Communication Speed of delivery is an essential property of audio and video forms of communication where information unfolds over a time course (Bosker, 2017). For instance, participating in a conversation, playing a radio broadcast, watching an advertisement on TV, listening to a lecture, and watching the news all involve perceiving stimuli presented in a sequence with a particular amount of information per unit of time. Synchronization of speech Consequences of Thought Speed 213 rate occurs spontaneously during interpersonal conversations (Kurzius, 2015). As a result, thought-speed research has implications for the produc- tion, delivery, and reception of communication. The consequences of such variations can be significant, as, for example, in the case of health communications designed to influence and promote health behaviors (Yang & Pronin, 2017). The rate of speech is a potent indicator of emotional tone in messages, especially for differentiating between sad and happy emotional content (Breinstein, van Lancker, & Daum, 2001). And “fast speakers” can be perceived as more intelligent, attractive, objective, persuasive, and credible, compared to “slow speakers” (Chebat et al., 2007; Miller, Maruyama, Beaber, & Valone, 1976; Street, Brady, & Putman, 1983). News stories spo- ken at a faster pace are rated more positively and induce more sympathetic arousal than slower-read ones (Kallinen & Ravaja, 2005). In the modern world of Internet and social media technologies, though, rapid speech is only one of a number of speedy communication methods that people are exposed to. For example, social media like Twitter present text in brief, densely packed, and constantly flowing stories. In an initial investigation of the consequences of exposure to such stimuli, Molouki and Pronin (unpublished) tested whether sentences constructed in the brief and dense style characteristic of Twitter posts induced subjectively faster speed of thinking compared to sentences written in a more conventional or “airy” style. Mechanical Turk participants (N¼95) who read Twitter-style sentences reported significantly faster thought speed compared to those who read conventional sentences (i.e., sentences that said the same thing but with less shorthand, fewer abbreviations, and overall more characters). However, there were no effects of the Twitter manipulation on postmanipulation mood or creativity, suggesting that reading Twitter-like text may be more complicated than a standard thought-speed manipulation. The thought-accelerating effects of electronically mediated communications like Twitter and instant messaging should be examined. There is a dearth of empirical research measuring how these novel technolog- ical forms of communication may influence thought speed.

9. CONCLUSION: THOUGHT SPEED IN THE MODERN WORLD

In this chapter, we reviewed a frequently overlooked dimension of the mind: the experience of speed in thinking. We may not be aware of the pace of our thinking until we experience sudden shifts, such as the malaise of being sick or a sudden inspiration from a flow of ideas. 214 Kaite Yang and Emily Pronin

But thought speed, and mundane alterations in it, are a constant property of our human existence. The idea of “today’s fast-paced world” seems like an apt description of contemporary society in the industrialized world. Never before has exposure to news, commentary, conversation, and information been as rapid and accessible as it is today (truly a fingertip away on mobile devices). It seems like new innovations in products and services, such as rideshare apps, mobile banking, fast food stores, and online dating, keep enabling more efficiency and more speed. Of course, these sentiments that life is racing by are not entirely new. Artists and writers from Virgil to Pink Floyd (e.g., “tempus fugit” and the song “Time”) have commented on the perception that time is limited, fleeting, or racing by. More recently, though, some have again voiced a nostalgic call to return to the slower past. Proponents of the Slow Movement emphasize the quality of relationships and experiences over the quantity of meetings that you attend or items on the schedule. For example, the “Slow Food” movement, which focuses on traditional (sometimes laborious) processes of preparing food and stopping to enjoy meals, began as a protest of the fast food industry (Hsu, 2014). Others caution that children’s creativity has been steadily decreasing as a consequence of technologies and lifestyles that increase the pace of living but do not allow as many opportunities for free play, face-to-face social interaction, and engagement in “reflective abstraction” (Kim, 2011). Why are the things that speed us up so irresistible? Our review may shed light on this question. Multiple lines of evidence from fields including social psychology, cognitive psychology, clinical psychology, psychopharmacology, neuroscience, and marketing research have pointed to the mood- uplifting, behaviorally activating, and physiologically arousing consequences of fast thinking, as well as to the depressing effects of slow thinking. Tem- porary states of being in a rush, of ideas taking flight, or simply of thinking more quickly than we were a minute ago, may not facilitate a nostalgic return to the “slow life,” but they may produce some of the positive feelings that we crave.

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