LCS 11: Introduction to Cognitive Science. Behaviorism Jesse Harris February 11, 2013 Background to behaviorism Much of philosophy has addressed what is sometimes known as ‘Plato’s problem’ – how do we come to know so much about the world, given our limited experience? Two important, though not necessarily mutually exclusive, strands of response are rationalism, with privileges reason over experience, and empiricism, which favors experience over reason.1 Rationalism How do we know so much about the world given our limited experi- ence? The rationalists propose that knowledge is deductive, in that we 1 In the Meno, Plato adopts a rationalist approach, ar- may glean knowledge from principles independent of experience. guing that knowledge is innately given and that the soul relies on experience Rationalism and reason to recollect that knowledge. His argument is illustrated by getting Knowledge is to be gained primarily through reason alone. a slave to “recollect” how to determine the areas of embedded squares like those above. With respect to questions of mind, rationalism is often associated with René Descartes, who modeled his method on geometric proofs from Euclid.2 Descartes wished to determine an incontrovertible 2 Euclid’s highly influential The Elements foundation of knowledge which was free of the possibility of illusion deduces Euclidean geometry from a limited set of axioms. Descartes and from the senses and which supported the immortality of the soul. others seemed to consider the axiomatic Descartes famously settled on a foundation of knowledge through method developed by Euclid to be the ideal form of scientific inquiry. the idea that, even if illusory, a thought must have a thinker: the very act of doubt verified some aspect of his existence! In other words, cognito ergo sum. There are three important methodological assump- tions that Descartes made: 1. Knowledge can be determined independently of the senses; 2. Ideas are transparent to conscious introspection; 3. We should privilege that which could be established by pure thought, e.g., mathematical truths, over the sense data of experi- ence Substance dualism The mind (soul) is a immaterial, immortal substance which exists independently of the body. lcs 11: introduction to cognitive science. behaviorism 2 Despite deeply ingrained problems with this view, substance dualism remains a popular view.3 An alternate, and just as venerable, view 3 Three prevalent considerations are as is known as empiricism, which treats the acquisition of knowledge as follows (see Cunningham, 2000, ch. 1) inductive. 1. Reliance on introspection 2. Causal separation 3. Development of mind Empiricism In contrast to rationalists, empiricists largely reject the assumption that ideas are innate. Instead, mental contents are derived from two factors. 1. Sensations – events with external causes. 2. Reflection – mental operations that associate external or internal states with other internal states. Together, these factors yield Ideas, mental contents likened to pictures or images, linked to what they are about. “Let us then suppose the mind to be, Empiricism as we say, white paper, void of all Knowledge is to be gained primarily through sense experience. character, without any ideas. How comes it to be furnished? . I answer, in one word, experience. In that, all our A prominent proponent of empiricism was John Locke, who devised knowledge is founded, and from that it ultimately derives itself.” a scheme for mental mechanics in which ideas come to be associated with one another. Through this kind of associationism, as it was called, Essay Concerning Human Understanding John Locke (1689) simple ideas compose to form more complex ones. Introspectionism Interestingly enough, the earliest experimental psychologists adopted elements, from both traditions. For example, Wilhelm Wundt and his student E. B. Titchener4 developed a method known as introspec- 4 tion, in which the contents of experience were reflected on during conscious investigation and reported back. In an attempt to make this process more scientific, participants were trained in introspec- tion through many trials, reporting their subjective experience.5 In particular, participants were instructed to decompose the process into discrete stages: perception of stimulus, a search for a response, Wilhelm Wundt E. B. Titchener identification of response, production of response, and so on. (1832–1920) (1867–1927) Exercise: Try this for yourself. View this 5 “The first order of the psychologist . is to ascertain the nature and num- swatch of red and reflect on the experience, ber of mental elements. He takes up attempting to break down the experience into mental experience, bit by bit, dividing as many components as you can. and subdividing, until the division can go no further. When that point is reached, he has found a conscious element.” An Outline of Psychology (Titchener, 1896) lcs 11: introduction to cognitive science. behaviorism 3 Behaviorism Frustration and disillusionment with introspection as a method of gaining entry into mental processes quickly mounted.6 John Wat- 6 “Take the case of sensation. A sensa- son and, later, B. F. Skinner,7 led the charge against the subjectivity tion is defined in terms of its attributes. One psychologist will state with readi- 8 seemingly inherent to the introspective method. They proposed a ness that the attributes of a visual purely behavioristic approach to studying the cognition, concerned sensation are quality, extension, dura- tion and intensity. Another will add in no small measure with the prediction and control of behavior. clearness. Still another that of order. I As discussed in Cunningham (2000), multiple kinds of behaviorism doubt if any one psychologist can draw resulted, notably, Methodological and Metaphysical Behaviorism. up a set of statements describing what he means by sensation which will be agreed to by three other psychologists Methodological behaviorism of different training.“ A scientific study of mind should eschew talk of the mind in favor Psychology as the Behaviorist Views It of a description of behavior, since only behavior provides publicly (Watson, 1913) observable, hence potentially verifiable, data. 7 Metaphysical behaviorism Mental events are reducible in kind to behavior: there is no substance or thing corresponding to what we call ‘mind.’ Influenced by the Vienna Circle’s circumscribed view of science,9 John B. Watson B.F. Skinner (1904–1990) behaviorism seeks to align, to various extents, the study of mind with (1878–1958) the study of behavior. That is, instead of worrying about the con- 8 “Psychology as the behaviorist views nection between mind and body, we focus on what we can observe: it is a purely objective experimental responses to external stimuli. Among the vocabulary central to Skin- branch of natural science. Its theoretical goal is the prediction and control ner’s behaviorism was operant conditioning, in which modification of of behavior. Introspection forms no behavior is voluntary. Skinner developed the so-called “Skinner box” essential part of its methods, nor is the to control an animal’s environment, typically a pigeon or white rat, scientific value of its data dependent upon the readiness of with which they starve them to create a “drive,” and then wait for animal to discover lend themselves to interpretation in a relation between the environment, e.g., a lever, and a reward, e.g., a terms of consciousness. The behaviorist . recognizes no dividing line between food pellet. Soon enough, the behavior is associated with the reward. man and brute.” Ibid. 9 The Vienna Circle refers to a group of philosophers and scientists in Vi- enna in the early 1920s who sought to eliminate what they deemed logical mistakes from philosophical questions. They thought that ambiguous language had radically misled scientific and philosophical inquiry, and proposed a unified science built on the foun- 10 In addition, Skinner placed animals on a schedule of reinforcement. dation of symbolic logic and publicly If a pigeon is fed at regular intervals regardless of its behavior, it will observable sense experience. adopt essentially arbitrary patterns of behavior which it has associ- 10 Skinner, B. F. (1948). ‘Superstition’ ated with the reward, such as spinning, pecking, etc. The efficacy of in the pigeon. Journal of Experimental the association could be manipulated by varying the rate of reward: Psychology 38, 168–272 lcs 11: introduction to cognitive science. behaviorism 4 fixed and random reinforcement. The strongest type was random re- inforcement, in which the animal is rewarded at random intervals. Indeed, it sometimes happened that although feeding device was dis- mantled, the pigeon indefinitely continued to perform the behavior that was associated with the reward. Thus, the behaviorist was able to account for admitedly simple behavior without recourse to unsightly mentalistic terms like desire, belief, and so forth. That is, the psychologist needn’t speculate about what the bird was feeling; she only needed to report its behavior. Encouraged by the success with pigeons and rats, Skinner and col- leagues proposed that the basic mechanism of association between a stimulus and response was the central, or even sole, mechanism driv- ing all behavior, even in human beings. Skinner even claimed that language learning was simply an instance of operant reinforcement, albeit complex in nature. For example, a child might be rewarded by her parents to cry out Papa in the presence of her father, thereby associating the word with the figure. In a devasting review by Noam Chomsky,11 it soon became apparent that Skinner’s science of behav- 11 Chomsky, N. (1959). Verbal Behavior. ior was simply not rich enough to account for more complex forms of By B. F. Skinner. Language 35, 26–58 speech or human behavior. Chomsky’s review is Indeed, even once committed behaviorists like Keller and Mar- widely regarded as the death knoll for 12 ian Breland observed that instinctive behaviors not driven by the behaviorism, mak- external environment were a powerful determinant of an animal’s ing commonsense, mentalistic talk once action.