Emotion Copyright 2006 by the American Psychological Association 2006, Vol. 6, No. 3, 392–405 1528-3542/06/$12.00 DOI: 10.1037/1528-3542.6.3.392

Awareness of Subtle Emotional : A Comparison of Long-Term Meditators and Nonmeditators

Lisbeth Nielsen Alfred W. Kaszniak National Institute on Aging University of Arizona

The authors explored whether meditation training to enhance emotional awareness improves discrimi- nation of subtle emotional feelings hypothesized to guide decision-making. Long-term meditators and nonmeditators were compared on measures of self-reported valence and , skin conductance response (SCR), and facial electromyography (EMG) to masked and nonmasked emotional pictures, and on measures of heartbeat detection and self-reported emotional awareness. Groups responded similarly to nonmasked pictures. In the masked condition, only controls showed discrimination in valence self-reports. However, meditators reported greater emotional clarity than controls, and meditators with higher clarity had reduced arousal and improved valence discrimination in the masked condition. These findings provide qualified support for the somatic marker hypothesis and suggest that meditation may influence how emotionally ambiguous information is processed, regulated, and represented in conscious awareness.

Keywords: meditation, , visual masking, subjective experience, somatic marker hypothesis

When selecting between two competing options, a rational tally features of the context. These processes could influence behavior of pros and cons often fails to identify a definitive choice. Rather, with or without the mediation of conscious feelings. On the one subtle conscious emotional intuitions may guide decisions. The hand, an unconscious physiological or evaluative change may somatic marker hypothesis (Bechara, Damasio, Tranel, & exert an implicit emotional on behavior (Winkielman, Ber- Damasio, 1997; Damasio, 1994) proposes that ridge, & Wilbarger, 2005). Alternatively, such unconscious emo- decision-making processes by signaling the goodness or badness tional processes may give rise to conscious feelings, which are of possible future outcomes. This process may be particularly then referenced when making a choice. important when the best option is uncertain. Making volitional choices on the basis of subtle changes in When people experience emotions in judgment or decision conscious emotional feelings requires some means by which an tasks, they typically attribute their feelings to task context features, option’s potential goodness versus badness is experienced. From a unless given good to do otherwise (Clore & Parrott, 1991; functional or evolutionary perspective, there is good to Schwarz & Clore, 1983). However, evidence from a gambling task think that both the valence and the arousal of a state suggests that, even in an impoverished context in which informa- provide important information to a behaving organism. Arousal tion about costs, benefits, and probability is not explicitly repre- signals the degree of self-relevance or uncertainty surrounding a sented, emotionally informative signals of the goodness or badness choice or behavioral option, whereas valence signals whether a of particular choices can nonetheless arise in the form of physio- particular option is beneficial or harmful to one’s interests. Thus, logic responses and conscious hunches regarding anticipated out- the dimensions of valence and arousal provide a framework for comes (Bechara et al., 1997). Such signals are thought to arise examining both the phenomenal structure and functional properties through preattentive evaluative processing of emotionally relevant of emotions related to decision making. In addition, individual differences in the ability to discriminate among subtle emotional signals along valence and arousal dimensions may have important Lisbeth Nielsen, Behavioral and Social Research Program, National consequences for adaptive behavior. Enhanced emotional aware- Institute on Aging; Alfred W. Kaszniak, Department of Psychology, Uni- ness may confer a greater ability to access, accurately identify, versity of Arizona. We thank John Allen, Ken Forster, Lynn Nadel, and Richard Lane at the regulate, and act on information conveyed in one’s feelings. University of Arizona, Shinzen Young, and Laura Carstensen and members The present study explores individual differences in emotional of the Life span Development Lab at Stanford University for their sugges- awareness at the very limits of consciousness, by probing aware- tions and comments on earlier versions of this paper. We would also like ness of the most subtle emotional feelings. The specific aims were to thank research assistants Brian David, Lindsey Littrell, and Katja Harle as follows: first, to discover whether there is a difference in very for their tireless contributions to this project. This research was carried out subtle phenomenal qualities of good (approach it) and bad (avoid as part of the dissertation research of LN at the University of Arizona and it) emotional intuitions elicited by masked pictures; and second, to funded by a University of Arizona Center for Consciousness Studies/Fetzer determine whether there are individual differences in the ability to Institute Small Research Grant to LN and AK. Correspondence concerning this article should be addressed to Lis consciously discriminate among those feelings, and whether such Nielsen, Behavioral and Social Research Program, National Institute on differences are related to (a) emotional awareness cultivated Aging, National Institutes of Health, 7201 Wisconsin Avenue, Suite 533, through long-term meditation practice, (b) visceral perception abil- Bethesda, MD 20892-9205. E-mail: [email protected] ity as assessed in a heartbeat detection task, and/or (c) self-reported

392 AWARENESS OF SUBTLE EMOTIONAL FEELINGS 393 emotional awareness as assessed by standardized questionnaires. Background Understanding the nature of individual differences in this ability may inform whether such skills can be cultivated through practices Visual Masking such as meditation or whether they represent underlying person- Despite claims about the advantages of enhanced emotional ality or perceptual differences. awareness, whether emotional feelings actually provide informa- tion about the valence of options remains an open question. Some Individual Differences evidence that preattentive emotional influences can bias behav- ior—with or without the aid of conscious feelings—comes from Why Meditation? studies using visual masking. In visual masking paradigms, a Buddhist meditation has been claimed to enhance emotional target stimulus is presented very briefly (Ͻ50 ms), followed— awareness and control through extensive practice involving focus and/or preceded—by a visual mask (a stimulus appearing in the on the features and dynamics of emotional responses (Goleman, same location as the target) to block or degrade conscious percep- 2003). A common Buddhist meditation practice involves carefully tion of the target to the degree that participants are unable or noting the emergence, transformation, and manifestation in aware- unwilling to report explicit awareness. Thus, masking allows for ness of the discrete components that make up an emotional state. some experimental control over the influences of reflective, con- Other practices focus for extended periods on bodily scious on the measurements of , so that changes phenomena such as the breath. Although there is no empirical in physiologic responding, judgment, or emotion experience that evidence to suggest that meditators are better at using emotional vary along with features of an emotional target stimulus can be information to inform decisions, years of training attention on the assumed to arise from the automatic activation of emotional pro- physiological and affective properties of emotional consciousness cesses based on a rough, preattentive analysis of those features. To during meditation may result in heightened discrimination of emo- be sure, as evidence from Maxwell and Davidson’s (2004) studies tional phenomenology in everyday life. Indeed, long-term Bud- with masked emotional facial expressions has made clear, absence dhist meditators have been described as possessing enhanced emo- of explicit awareness does not preclude higher order cognitive or tional awareness and improved emotional regulatory abilities perceptual processing (e.g., accurate discrimination in a forced- (Brazier, 2001; Dalai Lama & Cutler, 1998). Some behavioral and choice paradigm), and establishing unconscious perception in the physiological observations of long-term meditators are consistent laboratory remains an empirical challenge. However, masking with this description (see Goleman, 2003). For example, increased provides a useful technique for testing the question of whether left-sided anterior electroencephalogram (EEG) activation (asso- emotional feelings can be evoked, accessed, and influence behav- ciated with greater positive affect) was observed after 8 weeks of ior in the absence of explicit awareness (for further discussion, see training in mindfulness meditation (Davidson et al., 2003). Nielsen & Kaszniak, in press).

Visceral Perception Ability Preattentive Emotional Processing Feldman Barrett (1998) has documented individual differences Zajonc (1980) was an early advocate of the view that affective in the degree to which self-reports of emotion experiences empha- stimulus properties are rapidly processed and can exert global size valence or arousal and has linked these to individual differ- effects on preferences without the involvement of reflective, con- ences in visceral perception ability, as measured by a heartbeat scious cognition. Supporting research demonstrated that masked detection task (Feldman Barrett, Quigley, Bliss-Moreau, Aronson, affective primes exert bivalent influences on preference judgments 2004). Other studies have indicated that individuals with good of neutral targets (Murphy, Monahan & Zajonc, 1995; Murphy & heartbeat detection abilities report more intense emotion experi- Zajonc, 1993; Wong & Root, 2003) and that mere exposure to ences (Wiens, Mezzacappa, & Katkin, 2000) and more accurately neutral items (even when subliminal) increases subjective liking predict shocks contingent on backwardly masked -relevant (Kunst-Wilson & Zajonc, 1980; Monahan, Murphy, & Zajonc, stimuli (Katkin, Wiens, & Ohman, 2001). Consistent with theories 2000;). Evidence of bivalent physiologic change in response to of emotion that posit a central role of awareness of visceral states masked emotional faces has been found using facial electromyo- in the generation of emotional experience (Damasio, 1994; James, graphy (EMG; Dimberg, Thunberg, & Elmehed, 2000) and func- 1894/1994), visceral perception ability may be associated with tional magnetic resonance imaging (fMRI; Whalen et al., 1998). enhanced awareness of subtle emotional feelings, and meditation At the negative end of the valence dimension, O¨ hman and practice may strengthen such abilities. colleagues have shown that masked, aversively conditioned, fear- relevant stimuli, for which we have a biological preparedness Self-Reported Emotional Awareness (Seligman, 1970) to develop strong conditioned responses, elicit larger skin conductance responses (SCRs) and are rated as more Finally, some people simply attend more closely to emotions negative and more arousing than nonconditioned phobic or neutral and possess a greater ability to describe and classify their feelings. stimuli (O¨ hman & Soares, 1994, 1998; Esteves, Dimberg, & There is evidence that individual differences in self-reported emo- O¨ hman, 1994; see O¨ hman, Flykt, & Lundqvist, 2000, for a re- tional awareness predict how individuals make judgments in emo- view). This is true even when awareness of the conditioned tionally charged situations (Gohm, 2003). We hypothesized that stimulus–unconditioned stimulus (CS-UCS) contingency is meditation may influence self-reported emotional awareness and blocked using visual masking during acquisition of the fear re- that individuals reporting heightened emotional awareness on stan- sponse. However, participants report experiencing negative emo- dardized assessments would be more accurate at differentiating tions and accurately report anticipatory gut feelings of shock subtle feeling states. expectancy during this acquisition phase (O¨ hman & Soares, 1998). 394 NIELSEN AND KASZNIAK

More recently, Katkin, Wiens, and O¨ hman (2001) reported that Awareness of Subtle Emotional Feelings good heartbeat detectors are better at discerning such gut feelings, and they proposed that superior visceral perception underlies in- For the masked condition, we predicted that, when attention is dividual differences in conscious awareness of subtle emotional focused on changes in emotion experience on a trial-by-trial basis, somatic markers. These provocative findings fail to fully address subtle changes in experienced valence and arousal may be discern- the question of whether feeling states can inform decisions, be- able. We also predicted that, even in the absence of aversive cause the use of only negative and neutral stimuli makes it impos- conditioning (as used by O¨ hman & Soares, 1994, 1998), preatten- sible to ascertain whether participants experienced truly aversive tive processing of cues with biological salience would give rise to experiences or just heightened arousal—which they interpreted (in discrimination in SCR and facial EMG. In accordance with evo- the context of receiving electric shocks) as aversive. Whether lutionary arguments for a biological predisposition to respond appetitive (i.e., positively valenced) stimuli can also elicit both more strongly to aversive events (Cacioppo & Gardner, 1999; physiologic and subjective emotional responses preattentively re- Rozin & Royzman, 2001), we anticipated stronger responses to mains unknown. unpleasant than to pleasant masked stimuli. Evidence that preattentively elicited emotion gives rise to ex- periences of being emotionally aroused in a particular (valenced) direction is mixed. Monahan, Murphy, and Zajonc (2000) reported Individual Differences in Awareness that repeated subliminal exposure to neutral stimuli can increase We anticipated that long-term meditators would be better at positive mood, but Winkielman, Zajonc, and Schwarz (1997) found no evidence of awareness of subtle positive or negative discriminating the subtle feelings evoked by masked emotional feelings elicited by masked stimuli in retrospective posttask re- stimuli than controls. We also explored whether heartbeat detec- ports. However, because subtle shifts in feeling may be very brief tion accuracy or self-reported heightened awareness of for them short-lived, retrospective reports may be conferred additional discriminatory advantage. misleading. Only one study has reported bivalent experience changes in Method response to masked emotional stimuli. Robles, Smith, Carver, and Wellens (1987) inserted positive, negative, or neutral frames into Participants three separate, but otherwise identical, film clips and found biva- lent effects on ratings, suggesting that the response to Participants were 111 long-term meditators (9 female, 2 male) in the positive primes was qualitatively different from the response to Buddhist tradition and 17 nonmeditating controls (15 female, 2 male) negative or neutral primes. To the best of our knowledge, however, no study to date has assessed whether masked pleasant and un- pleasant stimuli can be distinguished from neutral stimuli in terms of both arousal and experienced positive or negative emotion. As 1 argued earlier, if feelings cannot tell us whether to approach or Initially 16 meditators were tested, with length of practice ranging from 4–29 years. Findings from videotaped structured interviews of emo- avoid an option, they will be of little use in guiding decisions. tional experiences revealed that this was not a homogeneous group as regards their approach to emotion experience. While a description of The Present Study interview methods is beyond the scope of this paper, the essential finding was that participants with less than 10 years of meditation practice had a particularly hyper-bodily focused approach to describing their emotional In the present study, participants viewed pleasant, neutral, and experiences that clearly distinguished them from their longer-term coun- unpleasant pictures with biologically salient content in both terparts. When comparing the percentage of statements containing bodily masked and nonmasked conditions. Self-reported valence and feeling reports that constituted descriptions of recent strong positive and arousal and physiological change in electrodermal activity (SCR) negative emotional experiences, short term meditators (M ϭ 33%, SD ϭ and corrugator and zygomatic facial electromyography (EMG) .08) used bodily feeling descriptors more often than long-term meditators were measured. ECG was also recorded, but will be reported (M ϭ 16%, SD ϭ .10), F(1, 30) ϭ 7.524, p Ͻ .005, ␩2 ϭ .334. Moreover, elsewhere. In the nonmasked condition, discrimination on all mea- the percentage of bodily feelings included in emotional reports was nega- ϭϪ Ͻ sures was expected to replicate prior findings, with pleasant and tively correlated with years of meditation practice (r .683, p .005, n ϭ 16). In addition, short term meditators had significantly more correct unpleasant pictures eliciting increased self-reported pleasant or responses on the heartbeat detection task, a measure of visceral awareness, unpleasant valence, increased arousal and SCR, and increased than their long-term counterparts, F(1, 13) ϭ 4.846, p Ͻ .05, ␩2 ϭ .272 corrugator (unpleasant) or zygomatic (pleasant) EMG compared (short term M ϭ 30.60, SD ϭ 5.5; long term M ϭ 24.8, SD ϭ 4.4), with neutral pictures (see Bradley & Lang, 2000, for a review). suggesting a greater attention to bodily states. Similar response patterns in the masked condition would be con- Based on these initial observations, we ran separate 2 Group (Short term, sidered to be consistent with preattentive emotional processing. In Long term) ϫ 3 Stimulus Type (Pleasant, Neutral, Unpleasant) repeated contrast to other studies assessing experiential responses to measures ANOVAs comparing short and long term meditators on our primary outcome variables: reports of experienced valence and arousal to masked visual primes, the present study examined responses to masked pictures. These tests further confirmed that short term meditators stimuli at both ends of the valence dimension for which there may were unlike their long term counterparts. There were significant differences be a biological predisposition to respond emotionally, and it in- in experienced arousal between the five short term and 11 long term corporated concurrent trial-by-trial self-reports of experienced va- meditators, Group ϫ Stimulus Type, F(2, 28) ϭ 4.554. p Ͻ .05, ␩2 ϭ .245, lence and arousal, along with physiological measures. with short term meditators reporting significantly higher levels of arousal AWARENESS OF SUBTLE EMOTIONAL FEELINGS 395 matched to the meditators on age (meditators: M ϭ 55.27 years, SD ϭ ware (developed at Monash University and at the University of Arizona by 10.43; controls: M ϭ 54.29, SD ϭ 10.0) and years of education (medita- K. I. Forster and J. C. Forster), which generated tones linked to the tors: M ϭ 18.27 years, SD ϭ 3.37; controls: M ϭ 18.97, SD ϭ 2.49). participant’s current R-wave and governed trial order using a randomiza- Meditators were recruited from local meditation centers. Control partici- tion algorithm. pants were recruited from University of Arizona staff and the surrounding community. All meditators had a regular practice sustained for over 10 Emotional Stimuli years (range ϭ 12–29 years, M ϭ 21.18, SD ϭ 4.73), practicing an average ϭ of 8.2 times per week (SD 4.2), for an average of 47 min per session The experimental stimuli were 16 neutral–low arousal, 16 unpleasant– ϭ 2 ϭϪ (SD 23). Length of practice was uncorrelated with age (r .13, ns). high arousal, and 16 pleasant–high arousal color pictures selected from the Participants had normal or corrected-to-normal vision and no history of International Affective Picture System (IAPS; Center for the Study of psychiatric or neurologic illness. Informed consent was obtained in accor- Emotion & Attention, 1999), divided into two sets, matched for both dance with University of Arizona human participants protection guidelines. content and normative ratings of valence and arousal. Emotional pictures Participants received $30 in compensation. were selected from categories likely to elicit “biologically prepared” re- sponses and included babies, happy and angry faces, nudes, spiders, Individual Difference Measures snakes, and vicious animals. Neutral stimuli were nonarousing, neutral- valenced pictures with biological content (humans, animals, and plants).4 Self-reported emotional awareness was assessed using the Toronto In pilot studies, ratings of pleasantness were found to increase as a function Alexithymia Scale (TAS; Taylor, Ryan, & Babgy, 1985), the Private of picture luminance. Consequently, the brightness of some of the original Self-Consciousness Scale (PSC; Fenigstein, Scheier, & Buss, 1975), the IAPS pictures was adjusted using image-processing software, so that the Mood Awareness Scale (MAS; Swinkels & Giuliano, 1995), the Trait mean luminance of pleasant, neutral, and unpleasant experimental stimuli Metamood Scale (TMM; Salovey, Mayer, Goldman, Turvey, & Palfai, was equated. Masks were constructed with image-processing software by 1995), and the Emotional Creativity Scale (ECS; Averill & Thomas- overlaying sections of six stimuli (two pleasant, two neutral, two unpleas- Knowles, 1991). On the basis of hierarchical cluster analyses of data ant); they were brightened, and randomly placed white abstract shapes collected from a sample of 151 college students, Gohm and Clore (2000) were inserted into each image, to create masks both complex and bright provided evidence that these scales constitute good measures of two trait enough to interrupt visual processing of the targets. Five independent dimensions of individual differences in emotion experience: attention to judges rated the masks on a 5-point version of the Self-Assessment Man- emotion, defined as “the extent to which individuals monitor their emo- ikin (SAM; Bradley & Lang, 1994). Only masks rated on average as tions, value their emotions, and maximize their experience of emotion” (p. neutral on valence and low on arousal were included in the study. Masks 684), and clarity, or “the ability to identify, distinguish, and describe for neutral, pleasant, and unpleasant stimuli were matched for luminance specific emotions” (p. 686). Gohm and Clore (2000) recommended the and mean red, blue, and green saturation. Labeling subscale of the MAS, the Clarity subscale of the TMM, and the Difficulty in Identifying Feelings subscale of the TAS (reverse scored) as good measures of clarity, while the ECS, the PSC, the Externally-Oriented Experimental Design Thinking subscale of the TAS (reverse scored), and the Monitoring sub- scale of the MAS were recommended as good measures of attention to In each of two testing sessions, participants viewed one set of stimuli emotion.3 masked and the other nonmasked, with conditions reversed in Session 2 Individual differences in visceral perception ability were assessed using and set order counterbalanced across participants. Six alternating blocks of a heartbeat detection task following the procedure outlined by Wiens, masked and nonmasked trials were presented in each session. Each stim- Mezzacappa, and Katkin (2000). The task consisted of 50 trials of 10 tones ulus valence was represented at least twice per block, with two pseudo- triggered by the R-wave of 10 consecutive beats of the participant’s heart. random stimulus orders counterbalanced across participants. Each session On half of the trials, the tones were presented 200 ms after the R-wave included eight catch trials with no emotional content (masked masks) to (typically perceived as synchronous); on the other half, there was a 500-ms assess discrimination accuracy and bias. delay (perceived as delayed; see Wiens & Palmer, 2000). In a practice Stimulus presentation and psychophysiological data acquisition were session, participants judged synchrony between a series of tones and a synchronized and controlled by a PC running DMDX software. Stimuli graphically displayed beating heart (cf. Katkin et al., 2001). In the actual were presented on a 17-in. (43.18-cm) computer monitor 30 in. (76.20 cm) task, participants sat upright in a recliner and were instructed to attend to from the participant. Trials began with a 4-s fixation cross. In the non- their heartbeats without feeling for their pulse and to verbally report masked condition, the stimulus then appeared for 3000 ms. In the masked whether tones on a given trial were “in synch” or delayed from actual heartbeats. We collected heartbeat data using a Biopac Systems ECG 2 amplifier, with output to a PC running AcqKnowledge software (Biopac One meditator (with 20 years of practice) reported no set schedule for Systems, Inc., Santa Barbara, CA; see below for recording parameters). formal practice, but that she had integrated “mindfulness” into her daily The AcqKnowledge program triggered another PC running DMDX soft- life. Of those providing information on their weekly practice, one meditator (with 29 years of practice) was unable to say how long her sessions lasted on average. 3 While other scales reviewed by Gohm and Clore (2000) measured to unpleasant (M ϭ 2.34, SD ϭ .95) than to pleasant (M ϭ 1.99, SD ϭ .82) factors like intensity of emotion, absorption in emotion, and emotional pictures ( p Ͻ .05), while long term meditators did not differ (pleasant M ϭ expressiveness, the clarity and attention factors were considered most 1.99, SD ϭ .70; unpleasant M ϭ 1.95, SD ϭ .66). In addition, comparisons likely to index the ability to attend to and distinguish subtle emotional of valence reports to masked pictures yielded a ns trend to a Group ϫ feeling states. Valence interaction, F(2, 28) ϭ 2.933, p ϭ .07, ␩2 ϭ .173. Short term 4 The IAPS pictures used in this study were: Set I (pleasant: 2150, 2344, meditators tended to experience unpleasant pictures as more unpleasant 1811, 4653, 4660, 2340, 2040, 2165; neutral: 5534, 2215, 2516, 5535, than did long term meditators (short term M ϭ 3.16, SD ϭ .23; long term 5510, 2383, 7550, 5520; unpleasant: 1300, 2900, 1274, 1050, 1200, 1052, M ϭ 2.93, SD ϭ .23, p ϭ .08). Because the small number of shorter-term 2800, 3060). Set II (pleasant: 4670, 2550, 2160, 2058, 2050, 4220 (for practitioners (n ϭ 5) enrolled in the study prohibited meaningful compar- males)/4520(for females), 2341, 1710; neutral: 2840, 2190, 5531, 9070, isons of both groups with our control participants, these individuals were 1616, 2495, 9210, 5530; unpleasant: 3168, 1120, 1270, 3170, 1220, 1930, excluded from analyses reported here. 1301, 1070). 396 NIELSEN AND KASZNIAK

condition, a 45-ms forward mask preceded a 45-ms presentation of the presentation and bioelectrical amplifiers for psychophysiological measure- target stimulus, followed by a reappearance of the mask for 2910 ms.5 In ment, participants were seated in an upright recliner for all tasks. In Session both conditions, a blank screen appeared for 4 s after stimulus presentation 1, participants completed a structured interview about emotion experiences while participants attended to their feeling states. Then, 5-point SAM and provided measures of heart rate variability as part of a separate study. valence and arousal scales appeared consecutively on the screen, and The electrodes for recording of skin conductance, ECG, and facial EMG participants entered their experience ratings on a keyboard. Finally, on were attached. Instructions for the picture-viewing task disclosed stimulus masked trials, participants responded either “yes” or “no” to a probe asking presentation parameters, mentioned prior findings of physiological re- whether they thought they had seen some identifiable feature or figure in sponses to masked stimuli, and highlighted the researchers’ interest in the briefly presented target stimulus. For the nonmasked trials, participants whether emotion experiences might also be elicited under masked presen- merely indicated by yes/no response whether they had seen the picture. tation conditions. Participants then viewed and rated a sample set of stimuli This ended the trial and triggered the onset of the next trial. before being left alone to complete the experiment. In Session 2, partici- Variations in stimulus features and individual differences in perceptual pants completed the second session of the picture-viewing task following thresholds and response are among the factors that can influence the procedure outlined earlier and then completed all psychometric mea- perception of masked stimuli (Maxwell & Davidson, 2004). By equating sures and the heartbeat detection task. stimuli for luminance and providing an explicit set of criteria for reporting awareness, we hoped to minimize some of this variation. Our purpose was Data Analysis to degrade perception to the extent that participants were unable or unwill- ing to report seeing a stimulus, and yet discrimination on other measures Individual difference measures. Raw scores on each psychometric (physiology, self-reported feelings) may be possible. scale or subscale were standardized with reference to sample means and standard deviations, and subscale z scores were summed to generate Emotion Ratings composite attention and clarity scores for each participant. Each participant received a score for total number of correct trials on the heartbeat detection Participants rated their experienced valence and arousal in response to task (200-ms delay tones reported as “in synch” or 500-ms delay reported all stimuli on 5-point versions of the SAM scales. Instructions for ratings as delayed). Additionally, following the procedure of Katkin, Wiens, & ¨ ϩ emphasized the focus on participants’ experienced emotion, regardless of Ohman (2001), individuals with 30 correct trials (binomial probability of Ͻ the objective content of the stimuli and regardless of how participants 30 out of 50 correct .05) were classified as good heartbeat detectors. thought they “ought” to feel. Participants were instructed to fully attend to Separate analyses of variance (ANOVAs) assessed differences between each stimulus and then focus their attention on their own subsequent meditators and controls in visceral perception ability, attention, clarity, and reaction, noting subtle changes in feelings and allowing these to inform associated subscales. Correlation analyses explored relationships between ratings on the valence and arousal scales. Examples of appropriate (e.g., age, length of meditation practice, self-reported emotion awareness, and “Ugh! That’s awful!”) and inappropriate (e.g., “That person must be visceral perception ability (number of correct trials on the heartbeat detec- feeling bad, so I’ll rate it negative”) criteria for making ratings were tion task). discussed during the practice session. Self-report and psychophysiological data. Mean valence rating, arousal rating, SCR magnitude, and EMG change were computed for each participant for each stimulus type (pleasant, neutral, unpleasant) in each Psychophysiological Measures: Recording and Data condition (masked, nonmasked), collapsed over the two viewing sessions. Reduction SCR variables were subjected to a square-root transformation to correct for skewed distributions. Repeated measures ANOVAs (2 [group] ϫ 3 [stim- SCR and facial EMG data were recorded using Biopac MP100 Systems ulus type] ϫ 2 [session]) revealed no significant main or interaction effects bio-amplifiers. Both measures were sampled at 1000 Hz for 4 s pre- and or trends related to day of testing in either condition; thus, order effects 11 s poststimulus onset. were not explored further. Arousal ratings were reverse coded to provide a SCR was recorded using a constant voltage (0.5 V) amplifier and 8-mm more intuitive representation on a scale ranging from 1 (not aroused)to5 Ag/AgCl electrodes filled with a pharmaceutically prepared electrolyte (very aroused). (0.05 molar NaCl in Unibase). Electrodes were attached to the medial We subjected all measures to 2 ϫ 3 ϫ 2 (Group ϫ Stimulus Type ϫ phalanges of the first and second fingers of the nondominant hand. The Condition) repeated measures ANOVAs, with alpha set at .05, using a skin conductance signal was low-pass filtered (10 Hz) and amplified 20 Greenhouse–Geisser correction for violations of the sphericity assumption. times. Before scoring, the signal was smoothed offline over a 100-ms Corrected degrees of freedom are reported where appropriate. We con- moving window and resampled at 20 Hz. For each stimulus, the amplitude ducted separate 2 ϫ 3 (Group ϫ Stimulus Type) repeated measures ␮ of the first SCR with minimum amplitude of 0.03 S and onset in the time ANOVAs for each condition, comparing the responses of meditators and window 1–4 s poststimulus onset was recorded. Trials with no measurable controls. Separate stimulus type repeated measures ANOVAs were con- SCR were assigned zero amplitude and included in all analyses. EMG signals were recorded from left and right corrugator and zygo- matic facial muscle sites, using electrode placements recommended by 5 It should be noted that the 45 ms target presentation is somewhat Fridlund and Cacioppo (1986). Two 4-mm Ag/AgCl electrodes were longer than the 30–33 ms typical in studies with emotional pictorial stimuli placed over each muscle site, with a ground placed in the center of the in which only backward masks have been employed. However, use of a ⍀ forehead. Impedances at all sites were less than 10 k . EMG signals were forward and backward mask, effectively consuming visual processing amplified 5000 times and notch filtered to remove 60 Hz noise. Signals capacity on both sides of the target, blocks explicit perceptual awareness, were bandpass filtered offline over a range of 10–500 Hz, rectified, and as indicated by self-report, at this slightly longer stimulus duration. Re- smoothed over a 20-ms moving window. Change scores in microvolts from search from lexical masked priming studies has demonstrated that at a 1-s prestimulus baseline were computed for all 100-ms epochs during the durations shorter than 50 ms, using forward and backward masks, partic- 3-s stimulus presentation period. ipants are surprised to learn that a target stimulus has been presented, while at durations from 60–67 ms, participants may be aware that something Procedure occurred, but are unable to identify the stimulus (Forster, Mohan, & Hector, 2003). The current study employed complex pictorial stimuli for Participants came to the laboratory on two separate occasions within a which such systematic examinations of perception at varying exposure 2-week period. In a small testing room containing a computer for stimulus durations have not been explored. AWARENESS OF SUBTLE EMOTIONAL FEELINGS 397

Table 1 Means and Standard Errors for Scores on the Clarity and Attention Dimensions of Self-Reported Emotional Awareness, and for Their Respective Subscales for 17 Controls and 11 Long-Term Meditators

Dimension Subscale Controls Meditators

Clarity Ϫ.78 (.72) 2.1 (.99) Labeling (MAS) 22.35 (.85) 26.82 (.88) Clarity (TMM) 40.71 (1.33) 46.45 (2.31) Difficulty Identifying Feelings (TAS)* 20.76 (1.20) 22.0 (1.49) Attention Ϫ.11 (.82) .13 (1.1) Emotional Creativity 103.44 (2.41) 97.40 (2.23) Private Self Consciousness 54.65 (2.55) 46.73 (4.17) Externally-Oriented Thinking (TAS)* 25.24 (.87) 25.18 (.81) Monitoring (MAS) 19.71 (.93) 21.18 (1.44)

Note. MAS ϭ Mood Awareness Scale; TMM ϭ Trait Metamood Scale; TAS ϭ Toronto Alexithymia Scale. * Indicates reverse scoring. ducted for controls and meditators in each condition to explore within- lated with composite scores of Attention (r ϭ .05), Clarity (r ϭ group effects on all measures. For meditators only, we included years of .13) or their subscales. One-way ANOVAs comparing good (n ϭ meditation practice as a covariate to explore whether length of practice 5) and nondiscriminating (n ϭ 21) heartbeat detectors revealed no enhanced discrimination. Planned pairwise comparisons between pleasant, significant differences in attention (good discrimination: M ϭ neutral, and unpleasant pictures were performed using the Dunn–Sidak ϭ ϭϪ ϭ correction for multiple comparisons. Clarity and attention scores were 0.76, SD 2.6; nondiscriminating: M 0.26, SD 3.4) or entered as covariates in separate subsequent analyses. We explored signif- clarity (good discrimination: M ϭ 0.64, SD ϭ 1.0; nondiscrimi- icant main effects or interactions with these variables using correlation nating: M ϭ 0.49, SD ϭ 3.7). Among meditators, years of practice analyses. Additional analyses compared good and nondiscriminating heart- was positively correlated with clarity, although not significantly so beat detectors on all measures. (r ϭ .35, p ϭ .31), but not with attention (r ϭϪ.09, ns)orthe Power considerations. Post hoc power analyses based on the present heartbeat detection score (r ϭ .13, ns).6 The absence of relation- sample size for within-participants repeated measures ANOVA, with alpha ships among these different measures of internal state awareness set at .05, were conducted with GPower software (Buchner, Erdfelder, & Faul, 1997). Power was .52 to detect medium effects and .87 to detect large suggests that they tap different abilities. Younger age was associ- effects: Critical F(1, 52) ϭ 4.03. Less conservative compromise power ated with higher scores on the Attention scale (r ϭϪ.55, p Ͻ .005) analysis, recommended by Buchner, Erdfelder and Faul (1997) for dealing and its Externally Oriented Thinking (TAS, reverse scored; r ϭ with limited samples, setting the ␤/␣ ratio at 1, indicated that our power Ϫ.40, p Ͻ .05) and Monitoring (MAS; r ϭϪ.50, p Ͻ .01) was .78 to detect medium effects, critical F(1, 52) ϭ 1.58, and .91 for large subscales; age was unrelated to other measures. effects, critical F(1, 52) ϭ 3.09.

Results The Picture Viewing Task Individual Differences in Emotional and Visceral Perception of masked stimuli. In all, 16 of 28 participants Awareness reported seeing some of the masked items, with these participants reporting a mean of 1.14 neutral (SD ϭ 2.01), 1.64 pleasant (SD ϭ Self-reported emotional awareness. Meditators reported 2.79), and 1.36 unpleasant (SD ϭ 1.36) items seen. There was no greater emotional clarity than controls, F(1, 26) ϭ 5.74, p Ͻ .05, difference in the number of items reported seen on Day 1 (M ϭ ␩2 ϭ .18, scoring significantly higher on the Labeling (MAS), F(1, 2.2, SD ϭ 3.8) versus Day 2 (M ϭ 1.9, SD ϭ 3.5) of testing, 26) ϭ 12.21, p Ͻ .005, ␩2 ϭ .32; and Clarity (TMM) subscales, 2 t(27) ϭ .78, p Ͼ .1. Meditators and controls did not differ in the F(1, 26) ϭ 5.38, p Ͻ .05, ␩ ϭ .17, with no differences in the ϭ Difficulty in Identifying Feelings subscale (TAS). Meditators and average number of masked items reported seen, F(1, 26) .22, ϭ ϭ ϭ ϭ controls did not differ on overall attention scores or attention p .65 (meditators: M 3.36, SD 3.93; controls: M 4.65, ϭ subscales. Table 1 shows means and standard errors on these SD 8.5). Only masked items reported as unseen were included measures. in calculation of individual participant means for all dependent Heartbeat detection. Data for the heartbeat detection task was variables. Nonmasked items that participants reported not seeing missing from 2 participants (1 meditator and 1 control) because of were likewise excluded. Equipment failures or experimenter errors irregular R-wave amplitudes. Meditators (M ϭ 24.8 correct, SD ϭ resulted in missing left corrugator data from 1 control participant, 4.4) and controls (M ϭ 26, SD ϭ 5.3) did not differ in performance and missing right corrugator data from 1 control and 2 meditators. on the heartbeat detection task. In all, 5 participants—1 meditator Individual differences. Among meditators, years of practice and 4 controls—were classified as good heartbeat detectors; all was not significantly associated with any of the outcome measures were female. Relations among individual difference measures. Attention and Clarity subscale scores were not significantly correlated (r ϭ 6 When short-term meditators were included, the relation between Clar- .11, ns), nor was the heartbeat detection score significantly corre- ity and years of meditation practice was stronger (r ϭ .485, p ϭ .06). 398 NIELSEN AND KASZNIAK

Figure 1. Mean valence (A. nonmasked condition; B. masked condition) and arousal (C. nonmasked condition; D. masked condition) ratings of meditators and controls, by stimulus type. Error bars represent standard errors. in either task condition.7 Attention to emotion and heartbeat de- .001) revealed that pleasant pictures (controls: M ϭ 2.82, SD ϭ tection ability failed to account for substantial performance differ- 0.73; meditators: M ϭ 2.68, SD ϭ 1.06) and unpleasant pictures ences, with single exceptions in each case, whereas clarity scores (controls: M ϭ 3.30, SD ϭ 0.90; meditators: M ϭ 3.34, SD ϭ related to several outcomes in the task, particularly among medi- 0.94) were rated as more arousing than neutral pictures (controls: tators. Age was not associated with valence discrimination on any M ϭ 1.94, SD ϭ 0.52; meditators: M ϭ 1.90, SD ϭ 0.58). On the measure. Significant findings are reported below. valence dimension, pleasant pictures were rated as more pleasant (controls: M ϭ 1.71, SD ϭ 0.44; meditators: M ϭ 1.83, SD ϭ Responses to Nonmasked Pictures 0.47) and unpleasant pictures as more unpleasant (controls: M ϭ ϭ ϭ ϭ The nonmasked condition served as a manipulation check on the 4.24, SD 0.42; meditators: M 4.04, SD 0.50) than neutral ϭ ϭ ϭ ability of the stimuli to evoke emotional responses and to illumi- pictures (controls: M 2.76, SD 0.26; meditators: M 2.71, ϭ nate any baseline group differences. The anticipated significant SD 0.40). effects of condition were found on all measures, with no signifi- Including clarity as a covariate in analyses of arousal ratings cant differences between meditators and controls in either self- revealed an ns trend to a Group ϫ Clarity interaction, F(1, 24) ϭ 2 reported emotion or psychophysiological responses to the non- 3.80, p ϭ .06, ␩ ϭ .14. Among meditators, clarity score was masked pictures. Self-reports of experienced arousal and valence. Figure 1 (A 7 This was also the case when these analyses included the 5 short-term and C) shows valence and arousal ratings of meditators and con- ϫ ϫ meditators, with one exception: Years of meditation interacted with Stim- trols in the nonmasked condition. A 2 3 (Group Stimulus ulus Type on Arousal ratings in the masked condition, F(2, 28) ϭ 3.421, Type) ANOVA yielded the predicted significant main effect of p Ͻ .05, ␩2 ϭ .20. Correlation analyses revealed that among meditators 2 stimulus type on arousal ratings, F(2, 52) ϭ 54.36, p Ͻ .001, ␩ ϭ (n ϭ 16) years of meditation practice was negatively correlated with 2 .68, and valence ratings, F(2, 52) ϭ 191.22, p Ͻ .001, ␩ ϭ .88, arousal ratings to masked neutral (r ϭϪ.21, ns) and unpleasant (r ϭϪ.28, but no difference between groups. Pairwise comparisons (all ps Ͻ ns), but not pleasant pictures (r ϭϪ.07). AWARENESS OF SUBTLE EMOTIONAL FEELINGS 399 negatively correlated with arousal ratings to nonmasked pictures detectors, while their responses to pleasant pictures (good discrim- (pleasant: r ϭϪ.46, ns; neutral: r ϭϪ.58, p ϭ .06; unpleasant: inators: M ϭ 0.19, SD ϭ 0.11; nondiscriminating: M ϭ 0.17, SD ϭ r ϭϪ.15, ns). Among controls, these correlations were all posi- 0.15; ns) did not differ. tive, although nonsignificant (pleasant: r ϭ .35, ns; neutral: r ϭ Facial EMG. Figure 3 (Panels A and C) illustrate left corru- .24, ns; unpleasant: r ϭ .25, ns). gator and zygomatic responses of meditators and controls in the Skin conductance. Figure 2A shows square-root transformed nonmasked condition. Separate 2 ϫ 3 (Group ϫ Stimulus Type) SCRs of meditators and controls in the nonmasked condition. A repeated measures ANOVAs on mean EMG change during the 3 s 2 ϫ 3 (Group ϫ Stimulus Type) ANOVA on SCRs yielded a of picture viewing revealed significant main effects of stimulus significant quadratic effect of stimulus type, F(1, 26) ϭ 11.03, p Ͻ type at corrugator sites on both the left, F(1.44, 35.93) ϭ 9.99, p Ͻ .005, ␩2 ϭ .298, with larger responses for both pleasant and .005, ␩2 ϭ .29, and right, F(1.08, 26.02) ϭ 4.57, p Ͻ .05, ␩2 ϭ unpleasant pictures, compared with neutral pictures, but no group .16. Pairwise comparisons revealed that pleasant pictures elicited main effect or Group ϫ Stimulus Type interaction, consistent with less corrugator activation than unpleasant pictures (left: p Ͻ .01; predictions. However, separate ANOVAs on the two groups re- right: ns trend p Ͻ .1) and neutral pictures (left: p Ͻ .01; right: p Ͻ vealed a stronger quadratic effect of stimulus type in the SCRs of .05). Corrugator responses to neutral and unpleasant pictures did controls, F(1, 16) ϭ 9.16, p Ͻ .005, ␩2 ϭ .30, than meditators, not significantly differ. Stimulus type also influenced zygomatic F(1, 10) ϭ 3.10, p Ͻ .1, ␩2 ϭ .25. activation on both the left, F(1.13, 29.28) ϭ 11.26, p Ͻ .005, ␩2 ϭ Skin conductance and individual differences. When Clarity .30, and right, F(1.10, 28.47) ϭ 10.92, p Ͻ .005, ␩2 ϭ .30. scale scores were included as a covariate in the analysis of SCRs, Pairwise comparisons revealed that pleasant pictures elicited sig- the significant quadratic effect of stimulus type remained, F(1, nificantly greater zygomatic activation than neutral pictures (left: 24) ϭ 7.17, p Ͻ .05, ␩2 ϭ .23, but there was a significant main p Ͻ .05; right: p Ͻ .01) and unpleasant pictures (left: p Ͻ .005; effect of clarity, F(1, 24) ϭ 4.18, p ϭ .05, ␩2 ϭ .15, qualified by right: p Ͻ .01). There were no differences between controls and a Group ϫ Clarity interaction, F(1, 24) ϭ 8.93, p Ͻ .01, ␩2 ϭ .27. meditators on any of these measures. Among meditators only, clarity was significantly negatively cor- ϭϪ Ͻ related with SCRs for all stimulus types (pleasant: r .77, p Responses to Masked Pictures .01; neutral: r ϭϪ.74, p Ͻ .01; unpleasant: r ϭϪ.68, p Ͻ .05), indicating a reduction in physiological arousal as clarity increases. Self-reports of experienced arousal and valence. A2ϫ 3 For controls, all correlations between Clarity subscale scores and (Group ϫ Stimulus Type) ANOVA comparing meditators and SCRs were nonsignificant, rs Յ .25. controls on arousal ratings to masked pictures yielded a significant In the only case in which visceral perception ability influenced quadratic effect of stimulus type, F(1, 26) ϭ 6.91, p Ͻ .05, ␩2 ϭ performance on the task, a 2 ϫ 3 (Group ϫ Stimulus Type) .21. Pairwise comparisons revealed nonsignificant trends for neu- ANOVA comparing good and nondiscriminating heartbeat detec- tral pictures to be rated as less arousing than both pleasant and tors on SCR in the nonmasked condition revealed a main effect of unpleasant pictures (pleasant: M ϭ 1.86, SD ϭ 0.64; neutral: M ϭ Stimulus Type, F(2, 48) ϭ 5.01, p Ͻ .01, ␩2 ϭ .17, and a 1.75, SD ϭ 0.61; unpleasant: M ϭ 1.84, SD ϭ 0.62; ps Ͻ.1). There significant Group ϫ Stimulus Type interaction, F(2, 48) ϭ 5.85, was no main effect of group or Group ϫ Stimulus Type interaction p Ͻ .005, ␩2 ϭ .20. Good heartbeat detectors had larger SCRs to on arousal ratings in the masked condition (see Figure 1D). unpleasant (good discriminators: M ϭ 0.32, SD ϭ 0.22; nondis- A2ϫ 3 (Group ϫ Stimulus Type) ANOVA on valence ratings criminating: M ϭ 0.14, SD ϭ 0.13; p Ͻ .05) and neutral pictures in the masked condition yielded a significant Group ϫ Stimulus (good discriminators: M ϭ 0.21, SD ϭ 0.13; nondiscriminating: Type interaction, F(2, 52) ϭ 4.15, p Ͻ .05, ␩2 ϭ .14. Pairwise M ϭ 0.09, SD ϭ 0.12; p ϭ .07) than nondiscriminating heartbeat comparisons revealed that controls rated masked unpleasant pic-

Figure 2. Square-root transformed SCRs of meditators and controls to pleasant, neutral, and unpleasant stimuli presented A) nonmasked and B) masked. Error bars represent standard errors. 400 NIELSEN AND KASZNIAK

Figure 3. Facial EMG activation change (in microvolts) in both meditators and controls in response to pleasant, neutral, and unpleasant pictures, measured as the difference between mean activation during the 3 seconds poststimulus onset and mean activation during the 1 second prestimulus period: A) left corrugator EMG change to nonmasked pictures; B) left corrugator EMG change to masked pictures; C) left zygomatic EMG change to nonmasked pictures; D) left zygomatic EMG change to masked pictures. Error bars represent standard errors. tures as significantly more unpleasant than meditators ( p Ͻ .05). group also emerged, F(1, 24) ϭ 4.09, p ϭ .05, ␩2 ϭ .15, qualified Separate three stimulus type ANOVAs on valence ratings in con- by an interaction of Group ϫ Clarity, F(1, 24) ϭ 5.93, p Ͻ .05, trols and meditators indicated that controls, F(2, 32) ϭ 4.65, p Ͻ ␩2 ϭ .20. Higher clarity scores were associated with lower arousal .05, ␩2 ϭ .23, were sensitive to valence information contained in ratings to all stimulus types in meditators (pleasant: r ϭϪ.74, p Ͻ the masked pictures, but meditators were not, F(2, 20) ϭ 0.94, p ϭ .01; neutral: r ϭϪ.76, p Ͻ .01; unpleasant: r ϭϪ.81, p Ͻ .005), .41, ␩2 ϭ .09. Planned pairwise comparisons indicated that con- but not controls (all rs Ͻ.2, ns). trols rated unpleasant masked pictures as significantly more un- When clarity was included as a covariate in the analysis of pleasant than pleasant masked pictures ( p Ͻ .05) with a tendency valence ratings, the Group ϫ Stimulus Type interaction remained, to rate them as more unpleasant than neutral masked pictures ( p ϭ F(2, 48) ϭ 7.22, p Ͻ .005, ␩2 ϭ .23, but a Stimulus Type ϫ .11), although ratings for neutral and pleasant pictures did not Clarity interaction emerged, F(2, 48) ϭ 3.18, p ϭ .05, ␩2 ϭ .12. differ (pleasant: M ϭ 2.99, SD ϭ 0.19; neutral: M ϭ 3.04, SD ϭ Among meditators only, Clarity scale scores were significantly 0.11; unpleasant: M ϭ 3.13, SD ϭ 0.17). This pattern in controls positively correlated with valence ratings to unpleasant pictures in is consistent with accurate valence discrimination (see Figure 1B). the masked condition (r ϭ .76, p Ͻ .01), which may be interpreted In contrast with controls, and counter to hypotheses, meditators did as a tendency to rate these stimuli as more unpleasant as clarity not discriminate among masked pictures on the valence dimension increases. All other correlations between clarity scale scores and (pleasant: M ϭ 3.04, SD ϭ 0.24; neutral: M ϭ 2.97, SD ϭ 0.35; valence ratings of masked items by either controls or meditators unpleasant: M ϭ 2.93, SD ϭ 0.23). were low, Ϫ.18 Ͻ r Ͻ .18, ns. Individual differences. When including clarity as a covariate Influences of masked stimulus awareness on ratings. One con- in the analysis of arousal ratings, the main effect of stimulus type trol participant reported seeing many more masked items than remained, F(2, 48) ϭ 6.17, p Ͻ .05, ␩2 ϭ .20, but a main effect of other participants (30 of 48 masked items; 17 on Day 1, 13 on Day AWARENESS OF SUBTLE EMOTIONAL FEELINGS 401

2). Excluding data from this participant did not alter the findings Exploratory Analyses of Valence Discrimination: A Signal of a significant main effect of stimulus type on arousal ratings, Detection Approach F(2, 50) ϭ 4.22, p Ͻ .05, ␩2 ϭ .14, or the significant Group ϫ Although the controls’ pattern of valence ratings in the masked Stimulus Type interaction on valence ratings, F(2, 50) ϭ 3.31, p Ͻ condition was in the predicted direction, specific accuracy (e.g., ␩2 ϭ .05, .12, with controls still showing a significant main effect actually rating pleasant stimuli as pleasant) could not be assessed ϭ ϭ ␩2 ϭ of stimulus type, F(2, 30) 3.23, p .05, .18. in the above analyses of mean differences. Recognizing the po- It was not possible to directly compare ratings of seen and tential for the following analyses to capitalize on chance, we were unseen items, as the average number of seen items was so small. nonetheless interested in exploring whether unique individual dif- However, including seen items in analyses eliminated effects of ferences were associated with accuracy in valence discrimination, stimulus type on valence ratings, suggesting that awareness of seen suggesting hypotheses for future study. Therefore, using a signal items was limited and possibly inaccurate. Rather than strength- detection approach, we sought to identify individual good valence ening the affective signal, beliefs or experiences of having seen an discriminators to determine whether, as a group, they shared any item may merely have added perceptual and/or affective noise. common features. Some evidence that the experiences of seen and not- seen trials Two separate signal detection analyses were conducted for were qualitatively different comes from the following finding. In pleasantness discrimination and unpleasantness discrimination, contrast to our findings for unseen masked items, when all seen yielding separate measures of sensitivity (dЈ) and willingness to masked items were pooled across participants, and ratings of endorse the presence of an emotional state (criterion) of pleasant- pleasant (n ϭ 47), neutral (n ϭ 32), and unpleasant (n ϭ 38) seen ness or unpleasantness. To assess valence discrimination, all pleas- items were compared, there was no significant influence of stim- ant or unpleasant masked items that participants reported not ulus type on either valence, F(2, 111) ϭ 0.19, p ϭ .83, or arousal seeing were modeled as signals. Of these, pleasant items rated as ratings, F(2, 111) ϭ 0.54, p ϭ .58. 1 or 2 on the 5-point valence scale were classified as pleasant hits; Skin conductance and facial EMG. As illustrated in Figure 2, unpleasant items rated as 4 or 5 were classified as unpleasant hits. SCR magnitude in the masked condition was unaffected by stim- Catch items (masked masks) were modeled as noise. The same 16 ulus type in either meditators or controls. There were likewise no catch items were included in assessments of both pleasantness and significant differences in facial muscle activation change from unpleasantness discrimination. Catch items rated as 1 or 2 were baseline in either corrugator or zygomatic muscle groups as a classified as false alarms for the pleasantness discrimination anal- function of stimulus type during the3sofstimulus presentation ysis, and catch items rated as 4 or 5 were classified as false alarms (see Figure 3). Separate analyses of EMG change in 500-ms for the analysis of unpleasantness discrimination. Data from the one control participant reporting a high number of seen masked epochs (cf. Dimberg et al., 2000) also failed to reveal significant items were excluded from these analyses, because of the unusually activation differences as a function of stimulus type. low number of items classified as signals in that particular case. The only influence of Attention scale scores was on SCRs to Among the remaining 27 participants, actual numbers of pleasant masked pictures. Covariance analysis yielded a significant main hits ranged from 0 to 10 (M ϭ 2.41, SD ϭ 2.58) and unpleasant effect of attention, F(1, 24) ϭ 4.51, p Ͻ .05, ␩2 ϭ .16. Attention hits ranged from 0 to 7 (M ϭ 2.78, SD ϭ 1.97) out of a maximum score was positively correlated with SCRs to all stimulus types, possible 16 items in each case.8 ϭ ϭ ϭ ϭ (pleasant: r .31, ns; neutral: r .37, p .05; unpleasant: r Pleasantness discrimination. Seven participants had positive ϭ .36, p .06), suggesting, perhaps not surprisingly, that individuals pleasantness dЈ values, ranging from 0.03 to 1.61. Of these only 4 inclined to attend to emotion were more physiologically aroused (all controls) had dЈ values of 0.5 or greater, an arbitrarily chosen when asked to attend to difficult-to-discern emotional states. demarcation value for distinguishing good discriminators from When Clarity was included as a covariate in the analysis of nondiscriminators. Good discriminators had more pleasantness SCRs, there was a significant Group ϫ Clarity interaction, F(1, hits (M ϭ 5.5, SD ϭ 3.7) and fewer false alarms (M ϭ 1.8, SD ϭ 24) ϭ 5.37, p Ͻ .05, ␩2 ϭ .18. Correlational analyses revealed 2.2) than nondiscriminators (hits: M ϭ 2.4, SD ϭ 2.6; false alarms: that, among meditators, clarity scores were negatively correlated M ϭ 2.9, SD ϭ 2.9). with SCRs to masked items (pleasant; r ϭϪ.77, p Ͻ .005; neutral: Unpleasantness discrimination. Fifteen participants had posi- r ϭϪ.47, p ϭ .15; unpleasant; r ϭϪ.58, p ϭ .06). Among tive unpleasantness dЈ values, ranging from 0.17 to 1.94. Of these, controls, these relations were not obtained (all rs Յ .3, ns). In 5 (4 controls, 1 meditator) had dЈ values Ͼ 0.5. By these criteria, addition, there was a significant Group ϫ Stimulus Type ϫ only 1 control participant was classified as good at both pleasant- Clarity interaction on left zygomatic responses, F(2, 48) ϭ ness and unpleasantness discrimination. Good unpleasantness dis- 5.03, p Ͻ .01, ␩2 ϭ .17, and a Group ϫ Clarity interaction on criminators had, on average, nominally more unpleasantness hits right zygomatic responses, F(1, 24) ϭ 5.77, p Ͻ .05, ␩2 ϭ .19. (M ϭ 3.8, SD ϭ 2.6) and fewer false alarms (M ϭ 1.2, SD ϭ 1.3) Among meditators, clarity scores were positively correlated than nondiscriminators (hits: M ϭ 2.6, SD ϭ 1.8; false alarms: with left and right zygomatic responses to masked pleasant M ϭ 2.9, SD ϭ 2.2). Pleasantness and unpleasantness dЈ values pictures (left: r ϭ .54, p ϭ .09; right: r ϭ .60, p Ͻ .05) and were not significantly correlated with heartbeat detection scores or neutral pictures (left: r ϭ .72, p Ͻ .05; right: r ϭ .73, p Ͻ .05) self-reported attention or clarity. Likewise, good and nondiscrimi- but only on the right for unpleasant pictures (left: r ϭ .28, ns; r ϭ p Ͻ right: .77, .01), whereas among controls, no significant 8 While the number of actual hits is small, it may underestimate the Յ correlations emerged (all rs .3, ns). Thus, meditators with number of items that support a discriminatory pattern, that is, pleasant Ͻ higher clarity had less physiological arousal to all stimuli and neutral Ͻ unpleasant on the valence dimension. This pattern could obtain more zygomatic activity in the masked condition. without any pleasant items actually being rated as pleasant. 402 NIELSEN AND KASZNIAK nators (pleasantness or unpleasantness) did not differ on these pleasant, pleasant masked stimuli elicited experiences that were measures. rated as arousing and neutral, and neutral masked stimuli elicited Relating awareness to valence discrimination. Pleasantness experiences that were rated as unarousing and neutral. Long-term and unpleasantness discrimination were uncorrelated with the meditation practice, heightened emotional attention, and enhanced number of items of either valence reported as seen, which suggests visceral perception ability were not specifically associated with that participants with good valence discrimination were not simply improved discrimination on the valence dimension. However, in more perceptually accurate. Moreover, there were no differences meditators only, emotional clarity was associated with more un- between good and nondiscriminators (pleasantness or unpleasant- pleasant ratings of unpleasant masked pictures. ness) in hit rates for seen items, which further suggests that Exploratory signal detection analyses of participants’ ability to reporting seeing a masked item did not translate into accurately extract specific pleasantness or unpleasantness information from assessing its valence. There were also no significant differences their reactions to masked stimuli revealed that controls had a between participants high and low in pleasantness or unpleasant- greater sensitivity to pleasantness information than meditators did, ness discrimination on SCR or EMG in the masked condition. whereas meditators were more likely to make pleasantness false Group differences in valence discrimination. Controls were alarms. better discriminators of pleasantness than meditators, F(1, 25) ϭ Ͻ ␩2 ϭ ϭ 5.07, p .05, .17, but not unpleasantness, F(1, 25) 1.93, Lack of Physiological Discrimination Among Masked Ͼ ␩2 ϭ p .1, .07. In addition, controls’ criterion for endorsing Stimuli pleasantness was higher, F(1, 25) ϭ 10.23, p Ͻ .005 (controls: M ϭ 1.75, SD ϭ 1.0; meditators: M ϭ 0.64, SD ϭ 0.63). Still, There was no discrimination among masked pictures on either meditators were willing to endorse valenced experiences in the of the physiological measures used in this study, despite discrim- masked condition, making significantly more pleasantness false ination in emotional self-report. It is not uncommon for the dif- alarms than controls, F(1, 25) ϭ 8.44, p Ͻ .01, ␩2 ϭ .25, with an ferent components of emotion to dissociate, with individual dif- average of 4.6 (SD ϭ 3.1) pleasantness false alarms, compared ferences revealed on one, but not all, of the measures of the with an average of 1.6 for controls (SD ϭ 2.2). Of note, meditators emotional response (Ferguson & Katkin, 1996; Lang, 1994; with higher clarity scores had fewer pleasantness false alarms in O¨ hman & Soares, 1998). However, the present findings stand in the masking task (r ϭϪ.54, p ϭ .09), although not better dis- contrast to prior studies using masked aversively conditioned crimination. Meditators with higher pleasantness false alarms had stimuli (Katkin et al., 2001; O¨ hman & Soares, 1993, 1994, 1998) higher arousal ratings to masked items of all types (rs Ͼ .66, ps Ͻ or masked pictures of facial affect (Dimberg et al., 2000) in which .05), whereas controls with higher false alarms (pleasant or un- physiological discrimination was observed. Design features may pleasant) reported higher arousal to masked unpleasant items only account largely for these differences. Aversive conditioning and (rs Ͼ .5, ps Ͻ .05). pictures of facial affect may be more effective at eliciting auto- nomic and somatic responses, respectively, under masked condi- Discussion tions than the unconditioned biological stimuli selected for this study. More sensitive physiological measures may yield different Summary of Findings findings.

In an emotion picture-viewing paradigm, in which stimuli were Individual Differences presented both masked and nonmasked, differences between long- term meditators and control participants were assessed on mea- Heartbeat detection. Heartbeat detection was unrelated to self- sures of self-reported emotion experience (valence and arousal) assessments of emotional awareness, suggesting that these mea- and emotional physiology (skin conductance and facial EMG). sures tap different abilities or constructs, the former perhaps a Individual differences associated with visceral perception ability more visceral and the latter a more reflective form of awareness. (as assessed by a heartbeat detection task), and self-assessed emo- Long-term meditators and controls did not differ in heartbeat tional attention and clarity (on standardized questionnaires), were detection ability, although more controls than meditators were also explored. In the nonmasked condition of the picture-viewing classified as good heartbeat detectors in this study. Good heartbeat task, there were no differences in physiological responses or in detectors had larger SCRs to nonmasked unpleasant and neutral self-reported emotion experiences of valence or arousal as a func- pictures than nondiscriminators, which was consistent with previ- tion of long-term meditation practice, suggesting a lack of differ- ously reported positive correlations between heartbeat detection ences in emotional responses between the two groups under stan- scores and several self-report measures of negative dard visual stimulus emotion-elicitation conditions. (Critchley et al., 2004). However, in the present study, this nega- There was no evidence of physiological discrimination in the tivity bias was not reflected in self-reported affect to the same masked condition. However, both groups showed the expected stimuli. Heartbeat detection ability has been linked with more pattern of arousal ratings. Contrary to hypotheses, only control pronounced facial expression of emotion (Ferguson & Katkin, participants were sensitive to valence information available in the 1996). Comparisons of EMG activations of good and nondiscrimi- masked stimuli. The combined pattern of valence and arousal nating heartbeat detectors in the present study did not corroborate discrimination among masked stimuli observed in controls sup- this finding. It should be noted that these analyses are compro- ports the assertion that subtle emotional feelings possess the qual- mised by the small number (n ϭ 5) of good heartbeat detectors in ities necessary to guide behavior. For each stimulus type, there was this study. a unique pattern of self-reported experience: Unpleasant masked Meditation and emotional clarity. Meditators rated themselves stimuli elicited experiences that were rated as arousing and un- higher than controls in emotional clarity—the ability to accurately AWARENESS OF SUBTLE EMOTIONAL FEELINGS 403 discriminate among and label one’s feeling states—and length of ory—has been found in older adults in numerous studies (see meditation practice was positively correlated with clarity score. Mather & Carstensen, 2005, for a review) and has been proposed Higher clarity scores in meditators were associated with the fol- to arise from a motivation to maintain well-being through emo- lowing: (a) a tendency to report lower arousal to all types of tional regulation (Carstensen, Fung, & Charles, 2003). Meditators, nonmasked stimuli, (b) lower arousal ratings to all masked stimuli, through practice, may develop similar regulatory skills, although at (c) more unpleasant ratings of valence experience after exposure to an earlier age.9 Although meditators seem to retain the ability to the masked unpleasant stimuli, (d) fewer pleasantness false alarms allow feelings to evolve under some circumstances—as in the in the masked condition, (e) lower SCRs in both the masked and nonmasked condition when asked to explore and report on the nonmasked conditions, and (f) increased zygomatic activity to nature of their feeling states—perhaps they develop, through prac- masked pictures. In controls, of whom only 3 had clarity scores tice, a disposition toward equanimity and positivity when stimuli exceeding the mean score of meditators, none of these relations are ambiguous. were obtained. In summary, lower physiological and experienced In summary, long-term meditation practice may entrain auto- were associated with higher clarity in meditators in both matic emotional regulatory mechanisms, fundamentally changing the masked and nonmasked conditions, whereas greater zygomatic the way in which practitioners respond to ambiguous emotional activity and improved valence detection were apparent only in the events and altering the quality of experiences through changes in masked condition. One possible interpretation of these findings is motivation and attention. When combined with heightened clarity, that the higher levels of clarity achieved by some meditators are such emotion regulation may permit accurate valence discrimina- accompanied by emotional regulatory skills honed through medi- tion against a background of equanimity. Clarity was positively tation practice that serve to dampen physiological and experienced correlated with years of meditation practice and with patterns of arousal and enhance positive facial expressions while simulta- emotional responding consistent with an emotional regulatory neously permitting increased accuracy in valence discrimination. skill. Perhaps these two skills—discrimination and regulation— Long-term meditation practice. Our findings suggest that non- develop separately in meditators and vie for priority, resulting in meditators are more sensitive to affective pleasant (approach it) the observed differences between meditators and controls in this and unpleasant (avoid it) feelings, raising questions about why study. One may speculate that in exceptionally highly trained long-term meditation practice did not more readily facilitate access meditators, such as Buddhist monks, both skills may be more to such potentially behaviorally useful information. Only long- finely honed. term meditators with very high levels of emotional clarity were sensitive to subtle negative feelings. This initially seemed puzzling because, according to Buddhist psychology, every conscious state Can Feelings Inform Choice? has a feeling tone—a quality of pleasantness, unpleasantness, or Our initial premise was that affective discrimination between neutrality—that the experienced meditator is trained to discrimi- pleasant and unpleasant pictures in the masked condition would nate (Goleman, 2003; Nyanaponika, 2000). These considerations provide evidence of a basis for subtle conscious emotional feelings were the motivation for our original, disconfirmed, hypotheses. that could serve as behavioral guides. Although prior research has However, Buddhist psychology itself may also help to explain demonstrated that negative affect can be elicited preattentively, the our seemingly counterintuitive findings. First, in tandem with present study offers evidence that visually masked “biologically efforts to cultivate emotional awareness, meditators strive to adopt relevant” stimuli of different valences can give rise to feeling an equanimous attitude of observing and letting go of their emo- states that differ on arousal and valence dimensions, and that there tions in an effort to avoid destructive and states of con- are individual differences in the ability to discriminate among sciousness that arise from holding on to negative feelings and those feelings. In natural environments, preattentive responses to thoughts (Goleman, 2003). The result of these efforts may be the negative emotional events may support species survival (LeDoux, development of emotion regulation strategies that reduce arousal, 1996; O¨ hman, Flykt, & Lundqvist, 2000). There are also plausible enhance positive affect, and prohibit feeling states—especially evolutionary reasons why preattentively elicited positive feelings those of uncertain origin, such as feelings evoked by masked might be adaptive, including the importance of emotion contagion stimuli—from being elaborated by cognitive appraisals of valence. for social interaction (Lundqvist & Dimberg, 1995), and role of According to Young (2003), “When feelings are experienced with positive emotional states in fostering seeking behavior and cogni- equanimity they assure their proper function as motivators and tive elaboration (Fredrickson, 1998; Panksepp, 1998). directors of behavior as opposed to driving and distorting behav- A better understanding of the role of emotions in guiding ior.” In contrast, controls’ less actively regulated emotional re- behavior will arise only from studies capable of exploring, in sponsivity may permit the elaboration of emotional states in re- parallel, the various channels that carry emotional information, so sponse to masked stimuli, resulting in the better valence that we can better assess which of the many components of discrimination observed in our sample. emotion is doing the functional work in any given decision con- As predicted, controls were more sensitive to unpleasant than text. Although scales representing valence and arousal provide a pleasant information in the masked stimuli, supporting the notion useful starting point, they do not capture many of the qualities of of a (Cacioppo & Gardner, 1999; Rozin & Royz- emotional feeling states that may nonetheless play an important man, 2001). Meditation practice, on the other hand, gave rise to an role in decision making. Future studies using concurrent measures apparent positivity effect reflected in more positive facial affect, a of physiology, behavior, and emotion experience in a variety of failure to rate ambiguous stimuli as negative, and a higher number of positive false alarms in the masked condition (except among meditators with very high clarity scores). 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