Verbal Behavior is a 1957 book by psychologistB. F. Skinner, in which he describes what he calls verbal behavior, or what was traditionally called linguistics.[1][2] Skinner's work describes the controlling elements of verbal behavior with terminology invented for the analysis - echoics, mands, tacts, autoclitics and others - as well as carefully defined uses of ordinary terms such as audience.
The origin of Verbal Behavior was an outgrowth of a series of lectures first presented at the University of Minnesota in the early 1940s and developed further in his summer lectures at Columbia and William James lectures at Harvard in the decade before the book's publication.[3]
Research
Skinner's analysis of verbal behavior drew heavily on methods of literary analysis.[4] This tradition has continued.[5] The book Verbal Behavior is almost entirely theoretical, involving little experimental research in the work itself.[6][7][8] Many research papers and applied extensions based on Verbal Behavior have been done since its publication.[9][10][11]
Skinner's Verbal Behavior also introduced the autoclitic and six elementary operants: mand, tact, audience relation, echoic, textual, and intraverbal.[12] For Skinner, the proper object of study is behavior itself, analyzed without reference to hypothetical (mental) structures, but rather with reference to the functional relationships of the behavior in the environment in which it occurs. This analysis extends Ernst Mach's pragmatic inductive position in physics, and extends even further a disinclination towards hypothesis-making and testing.[13]Verbal Behavior is divided into 5 parts with 19 chapters.[1][14] The first chapter sets the stage for this work, a functional analysis of verbal behavior. Skinner presents verbal behavior as a function of controlling consequences and stimuli, not as the product of a special inherent capacity. Neither does he ask us to be satisfied with simply describing the structure, or patterns, of behavior. Skinner deals with some alternative, traditional formulations, and moves on to his own functional position.
General problems
In the ascertaining of the strength of a response Skinner suggests some criteria for strength (probability): emission, energy-level, speed, and repetition. He notes that these are all very limited means for inferring the strength of a response as they do not always vary together and they may come under the control of other factors. Emission is a yes/no measure, however the other three—energy-level, speed, repetition—comprise possible indications of relative strength.[15]
Emission – If a response is emitted it may tend to be interpreted as having some strength. Unusual or difficult conditions would tend to lend evidence to the inference of strength. Under typical conditions it becomes a less compelling basis for inferring strength. This is an inference that is either there or not, and has no gradation of value.
Energy-level – Unlike emission as a basis for inference, energy-level (response magnitude) provides a basis for inferring the response has a strength with a high range of varying strength. Energy level is a basis from which we can infer a high tendency to respond. An energetic and strong "Water!" forms the basis for inferring the strength of the response as opposed to a weak, brief "Water".[15]
Speed – Speed is the speed of the response itself, or the latency from the time in which it could have occurred to the time in which it occurs. A response given quickly when prompted forms the basis for inferring a high strength.[15]
Repetition – "Water! Water! Water!" may be emitted and used as an indication of relative strength compared to the speedy and/or energetic emission of "Water!". In this way repetition can be used as a way to infer strength.
Chapter Three of Skinner's work Verbal Behavior discusses a functional relationship called the mand. Mand is verbal behavior under functional control of satiation or deprivation (that is, motivating operations) followed by characteristic reinforcement often specified by the response. A mand is typically a demand, command, or request. The mand is often said to "describe its own reinforcer" although this is not always the case, especially as Skinner's definition of verbal behavior does not require that mands be vocal. A loud knock at the door, may be a mand "open the door" and a servant may be called by a hand clap as much as a child might "ask for milk".
Lamarre & Holland (1985) study on mands demonstrated the role of motivating operations.[16] The authors contrived motivating operations for objects by training behavior chains that could not be completed without certain objects. The participants learned to mand for these missing objects, which they had previously only been able to tact...
Behavior under the control of verbal stimuli
Textual
In Chapter Four Skinner notes forms of control by verbal stimuli. One form is textual behavior which refers to the type of behavior we might typically call reading or writing. A vocal response is controlled by a verbal stimulus that is not heard. There are two different modalities involved ("reading"). If they are the same they become "copying text" (see Jack Michael on copying text), if they are heard, then written, it becomes "taking dictation", and so on.
Echoic
Skinner was one of the first to seriously consider the role of imitation in language learning. He introduced this concept into his book Verbal Behavior with the concept of the echoic. It is a behavior under the functional control of a verbal stimulus. The verbal response and the verbal stimulus share what is called point to point correspondence (a formal similarity.) The speaker repeats what is said. In echoic behavior, the stimulus is auditory and response is vocal. It is often seen in early shaping behavior. For example, in learning a new language, a teacher might say "parsimonious" and then say "can you say it?" to induce an echoic response. Winokur (1978) is one example of research about echoic relations.[17]
Chapter Five of Verbal Behavior discusses the tact in depth. A tact is said to "make contact with" the world, and refers to behavior that is under functional control of a non-verbal stimulus and generalized conditioned reinforcement. The controlling stimulus is nonverbal, "the whole of the physical environment". In linguistic terms, the tact might be regarded as "expressive labelling". Tact is the most useful form of verbal behaviour to other listeners, as it extends the listeners contact with the environment. In contrast, the tact is the most useful form of verbal behaviour to the speaker as it allows to contact tangible reinforcement. Tacts can undergo many extensions: generic, metaphoric, metonymical, solecistic, nomination, and "guessing". It can also be involved in abstraction. Lowe, Horne, Harris & Randle (2002) would be one example of recent work in tacts.[18]
Intraverbal
Intraverbals are verbal behavior under the control of other verbal behavior. Intraverbals are often studied by the use of classic association techniques.[19]
Audiences
Audience control is developed through long histories of reinforcement and punishment. Skinner's three-term contingency can be used to analyze how this works: the first term, the antecedent, refers to the audience, in whose presence the verbal response (the second term) occurs. The consequences of the response are the third term, and whether or not those consequences strengthen or weaken the response will affect whether that response will occur again in the presence of that audience. Through this process, audience control, or the probability that certain responses will occur in the presence of certain audiences, develops. Skinner notes that while audience control is developed due to histories with certain audiences, we do not have to have a long history with every listener in order to effectively engage in verbal behavior in their presence (p.176). We can respond to new audiences (new stimuli) as we would to similar audiences with whom we have a history.
Negative audiences
An audience that has punished certain kinds of verbal behavior is called a negative audience (p.178): in the presence of this audience, the punished verbal behavior is less likely to occur. Skinner gives examples of adults punishing certain verbal behavior of children, and a king punishing the verbal behavior of his subjects.
Summary of verbal operants
The following table[20] summarizes the new verbal operants in the analysis of verbal behavior.
Precondition
Verbal Operant
Consequence
Example
Motivating Operation
Mand
Directly Effective
A child comes into the kitchen where a mother is, and says: "I want milk". The mother opens the refrigerator and gives the child milk.
Feature of the physical environment
Tact
Social
A child looks out of the window, turns to his mother and says: "It is hot today." The mother says, "Right!"
Verbal behavior of another person
Intraverbal
Social
A mother asks her daughter: "What grade did you get in math?" The daughter replies, "An A." The mother says: "Very good!"
Verbal behavior of another person
Echoic
Social
A teacher says to a student: "Behavior in German is Verhalten." The student repeats "Behavior is Verhalten." The teacher says "Correct."
A person's own verbal behavior
Autoclitic
Directly Effective
A child comes into his parents' bedroom at night and says "I think I am sick." The mother takes the child and brings him to a hospital.
Verbal operants as a unit of analysis
Skinner notes his categories of verbal behavior: mand, textual, intraverbal, tact, audience relations, and notes how behavior might be classified. He notes that form alone is not sufficient (he uses the example of "fire!" having multiple possible relationships depending on the circumstances). Classification depends on knowing the circumstances under which the behavior is emitted. Skinner then notes that the "same response" may be emitted under different operant conditions.[21] Skinner states:
"Classification is not an end in itself. Even though any instance of verbal behavior can be shown to be a function of variables in one or more of these classes, there are other aspects to be treated. Such a formulation permits us to apply to verbal behavior concepts and laws which emerge from a more general analysis" (p. 187).[22]
That is, classification alone does little to further the analysis—the functional relations controlling the operants outlined must be analyzed consistent with the general approach of a scientific analysis of behavior.
Multiple causation
Skinner notes in this chapter how any given response is likely to be the result of multiple variables. Secondly, that any given variable usually affects multiple responses.[23] The issue of multiple audiences is also addressed, as each audience is, as already noted, an occasion for strong and successful responding. Combining audiences produces differing tendencies to respond.[24][25]
Supplementary stimulation
Supplementary stimulation is a discussion to practical matters of controlling verbal behavior given the context of material which has been presented thus far. Issues of multiple control, and involving many of the elementary operants stated in previous chapters are discussed.
New combinations of fragmentary responses
A special case of where multiple causation comes into play creating new verbal forms is in what Skinner describes as fragmentary responses. Such combinations are typically vocal, although this may be due to different conditions of self-editing rather than any special property. Such mutations may be "nonsense" and may not further the verbal interchange in which it occurs. Freudian slips may be one special case of fragmentary responses which tend to be given reinforcement and may discourage self-editing. This phenomenon appears to be more common in children, and in adults learning a second language. Fatigue, illness and insobriety may tend to produce fragmentary responding.
An autoclitic is a form of verbal behavior which modifies the functions of other forms of verbal behavior. For example, "I think it is raining" possesses the autoclitic "I think" which moderates the strength of the statement "it is raining". An example of research that involved autoclitics would be Lodhi & Greer (1989).[26]
Self-strengthening
Here Skinner draws a parallel to his position on self-control and notes: "A person controls his own behavior, verbal or otherwise, as he controls the behavior of others."[27] Appropriate verbal behavior may be weak, as in forgetting a name, and in need of strengthening. It may have been inadequately learned, as in a foreign language. Repeating a formula, reciting a poem, and so on. The techniques are manipulating stimuli, changing the level of editing, the mechanical production of verbal behavior, changing motivational and emotional variables, incubation, and so on. Skinner gives an example of the use of some of these techniques provided by an author.
Logical and scientific
The special audience in this case is one concerned with "successful action". Special methods of stimulus control are encouraged that will allow for maximum effectiveness. Skinner notes that "graphs, models, tables" are forms of text that allow for this kind of development. The logical and scientific community also sharpens responses to assure accuracy and avoid distortion. Little progress in the area of science has been made from a verbal behavior perspective; however, suggestions of a research agenda have been laid out.[28][29]
Tacting private events
Private events are events accessible to only the speaker. Public events are events that occur outside of an organism's skin that are observed by more than one individual. A headache is an example of a private event and a car accident is an example of a public event.
The tacting of private events by an organism is shaped by the verbal community who differentially reinforce a variety of behaviors and responses to the private events that occur (Catania, 2007, p.9). For example, if a child verbally states, "a circle" when a circle is in the immediate environment, it may be a tact. If a child verbally states, "I have a toothache", she/he may be tacting a private event, whereas the stimulus is present to the speaker, but not the rest of the verbal community.
The verbal community shapes the original development and the maintenance or discontinuation of the tacts for private events (Catania, 2007, p.232). An organism responds similarly to both private stimuli and public stimuli (Skinner, 1957, p.130). However, it is harder for the verbal community to shape the verbal behavior associated with private events (Catania, 2007, p.403). It may be more difficult to shape private events, but there are critical things that occur within an organism's skin that should not be excluded from our understanding of verbal behavior (Catania, 2007, p.9).
Several concerns are associated with tacting private events. Skinner (1957) acknowledged two major dilemmas. First, he acknowledges our difficulty with predicting and controlling the stimuli associated with tacting private events (p.130). Catania (2007) describes this as the unavailability of the stimulus to the members of the verbal community (p.253). The second problem Skinner (1957) describes is our current inability to understand how the verbal behavior associated with private events is developed (p.131).
Skinner (1957) continues to describe four potential ways a verbal community can encourage verbal behavior with no access to the stimuli of the speaker. He suggests the most frequent method is via "a common public accompaniment". An example might be that when a kid falls and starts bleeding, the caregiver tells them statements like, "you got hurt". Another method is the "collateral response" associated with the private stimulus. An example would be when a kid comes running and is crying and holding their hands over their knee, the caregiver might make a statement like, "you got hurt". The third way is when the verbal community provides reinforcement contingent on the overt behavior and the organism generalizes that to the private event that is occurring. Skinner refers to this as a "metaphorical or metonymical extension". The final method that Skinner suggests may help form our verbal behavior is when the behavior is initially at a low level and then turns into a private event (Skinner, 1957, p.134). This notion can be summarized by understanding that the verbal behavior of private events can be shaped through the verbal community by extending the language of tacts (Catania, 2007, p.263).
Private events are limited and should not serve as "explanations of behavior" (Skinner, 1957, p.254). Skinner (1957) continues to caution that, "the language of private events can easily distract us from the public causes of behavior" (see functions of behavior).
Chomsky's review and replies
In 1959, Noam Chomsky published an influential critique of Verbal Behavior.[30] Chomsky pointed out that children acquire their first language without being explicitly or overtly "taught" in a way that would be consistent with behaviorist theory (see Language acquisition and Poverty of the stimulus), and that Skinner's theories of "operants" and behavioral reinforcements are not able to account for the fact that people can speak and understand sentences that they have never heard before.
Chomsky's review has come to be regarded as one of the foundational documents of the discipline of cognitive psychology, and even after the passage of twenty-five years it is considered the most important refutation of behaviorism. Of all his writings, it was the Skinner review which contributed most to spreading his reputation beyond the small circle of professional linguists.[31]
Chomsky's 1959 review, amongst his other work of the period, is generally thought to have been influential in the decline of behaviorism's influence within linguistics, philosophy and cognitive science.[32][33] One reply to it was Kenneth MacCorquodale's 1970 paper On Chomsky's Review of Skinner's Verbal Behavior.[34] MacCorquodale argued that Chomsky did not possess an adequate understanding of either behavioral psychology in general, or the differences between Skinner's behaviorism and other varieties. As a consequence, he argued, Chomsky made several serious errors of logic. On account of these problems, MacCorquodale maintains that the review failed to demonstrate what it has often been cited as doing, implying that those most influenced by Chomsky's paper probably already substantially agreed with him. Chomsky's review has been further argued to misrepresent the work of Skinner and others, including by taking quotes out of context.[35] Chomsky has maintained that the review was directed at the way Skinner's variant of behavioral psychology "was being used in Quinean empiricism and naturalization of philosophy".[36]
Current research
Current research in verbal behavior is published in The Analysis of Verbal Behavior[37] (TAVB), and other Behavior Analytic journals such as The Journal of the Experimental Analysis of Behavior (JEAB) and the Journal of Applied Behavior Analysis (JABA). Also research is presented at poster sessions and conferences, such as at regional Behavior Analysis conventions[38] or Association for Behavior Analysis (ABA)[39] conventions nationally or internationally. There is also a Verbal Behavior Special Interest Group (SIG)[40] of the Association for Behavior Analysis (ABA) which has a mailing list.[41]
Journal of Early and Intensive Behavior Intervention[42] and the Journal of Speech-Language Pathology and Applied Behavior Analysis[43] both publish clinical articles on interventions based on verbal behavior.
Skinner has argued that his account of verbal behavior might have a strong evolutionary parallel.[44] In Skinner's essay, Selection by Consequences he argued that operant conditioning was a part of a three-level process involving genetic evolution, cultural evolution and operant conditioning. All three processes, he argued, were examples of parallel processes of selection by consequences. David L. Hull, Rodney E. Langman and Sigrid S. Glenn have developed this parallel in detail.[45] This topic continues to be a focus for behavior analysts.[46][47] Behavior analysts have been working on developing ideas based on Verbal Behaviour for fifty years, and despite this, experience difficulty explaining generative verbal behavior.[48]
Burrhus Frederic Skinner was an American psychologist, behaviorist, inventor, and social philosopher. He was the Edgar Pierce Professor of Psychology at Harvard University from 1958 until his retirement in 1974.
Operant conditioning, also called instrumental conditioning, is a learning process where voluntary behaviors are modified by association with the addition of reward or aversive stimuli. The frequency or duration of the behavior may increase through reinforcement or decrease through punishment or extinction.
An operant conditioning chamber is a laboratory apparatus used to study animal behavior. The operant conditioning chamber was created by B. F. Skinner while he was a graduate student at Harvard University. The chamber can be used to study both operant conditioning and classical conditioning.
In behavioral psychology, reinforcement refers to consequences that increase the likelihood of an organism's future behavior, typically in the presence of a particular antecedent stimulus. For example, a rat can be trained to push a lever to receive food whenever a light is turned on. In this example, the light is the antecedent stimulus, the lever pushing is the operant behavior, and the food is the reinforcer. Likewise, a student that receives attention and praise when answering a teacher's question will be more likely to answer future questions in class. The teacher's question is the antecedent, the student's response is the behavior, and the praise and attention are the reinforcements.
Radical behaviorism is a "philosophy of the science of behavior" developed by B. F. Skinner. It refers to the philosophy behind behavior analysis, and is to be distinguished from methodological behaviorism—which has an intense emphasis on observable behaviors—by its inclusion of thinking, feeling, and other private events in the analysis of human and animal psychology. The research in behavior analysis is called the experimental analysis of behavior and the application of the field is called applied behavior analysis (ABA), which was originally termed "behavior modification."
The experimental analysis of behavior is a science that studies the behavior of individuals across a variety of species. A key early scientist was B. F. Skinner who discovered operant behavior, reinforcers, secondary reinforcers, contingencies of reinforcement, stimulus control, shaping, intermittent schedules, discrimination, and generalization. A central method was the examination of functional relations between environment and behavior, as opposed to hypothetico-deductive learning theory that had grown up in the comparative psychology of the 1920–1950 period. Skinner's approach was characterized by observation of measurable behavior which could be predicted and controlled. It owed its early success to the effectiveness of Skinner's procedures of operant conditioning, both in the laboratory and in behavior therapy.
Behaviorism is a systematic approach to understand the behavior of humans and other animals. It assumes that behavior is either a reflex evoked by the pairing of certain antecedent stimuli in the environment, or a consequence of that individual's history, including especially reinforcement and punishment contingencies, together with the individual's current motivational state and controlling stimuli. Although behaviorists generally accept the important role of heredity in determining behavior, they focus primarily on environmental events. The cognitive revolution of the late 20th century largely replaced behaviorism as an explanatory theory with cognitive psychology, which unlike behaviorism examines internal mental states.
Applied behavior analysis (ABA), also called behavioral engineering, is a psychological intervention that applies approaches based upon the principles of respondent and operant conditioning to change behavior of social significance. It is the applied form of behavior analysis; the other two forms are radical behaviorism and the experimental analysis of behavior.
Relational frame theory (RFT) is a psychological theory of human language, cognition, and behaviour. It was developed originally by Steven C. Hayes of University of Nevada, Reno and has been extended in research, notably by Dermot Barnes-Holmes and colleagues of Ghent University.
In operant conditioning, punishment is any change in a human or animal's surroundings which, occurring after a given behavior or response, reduces the likelihood of that behavior occurring again in the future. As with reinforcement, it is the behavior, not the human/animal, that is punished. Whether a change is or is not punishing is determined by its effect on the rate that the behavior occurs. This is called motivating operations (MO), because they alter the effectiveness of a stimulus. MO can be categorized in abolishing operations, decrease the effectiveness of the stimuli and establishing, increase the effectiveness of the stimuli. For example, a painful stimulus which would act as a punisher for most people may actually reinforce some behaviors of masochistic individuals.
In behavioral psychology, stimulus control is a phenomenon in operant conditioning that occurs when an organism behaves in one way in the presence of a given stimulus and another way in its absence. A stimulus that modifies behavior in this manner is either a discriminative stimulus or stimulus delta. For example, the presence of a stop sign at a traffic intersection alerts the driver to stop driving and increases the probability that braking behavior occurs. Stimulus control does not force behavior to occur, as it is a direct result of historical reinforcement contingencies, as opposed to reflexive behavior elicited through classical conditioning.
The behavioral analysis of child development originates from John B. Watson's behaviorism.
Tact is a term that B.F. Skinner used to describe a verbal operant which is controlled by a nonverbal stimulus and is maintained by nonspecific social reinforcement (praise).
Mand is a term that B.F. Skinner used to describe a verbal operant in which the response is reinforced by a characteristic consequence and is therefore under the functional control of relevant conditions of deprivation or aversive stimulation. One cannot determine, based on form alone, whether a response is a mand; it is necessary to know the kinds of variables controlling a response in order to identify a verbal operant. A mand is sometimes said to "specify its reinforcement" although this is not always the case. Skinner introduced the mand as one of six primary verbal operants in his 1957 work, Verbal Behavior.
Autoclitics are verbal responses that modify the effect on the listener of the primary operants that comprise B.F. Skinner's classification of Verbal Behavior.
The Analysis of Verbal Behavior (TAVB) is a peer reviewed, scientific journal established in 1982, which primarily publishes research in the field of psychology focused on the conceptual and empirical analysis of verbal behavior.
James "Jim" A. Dinsmoor was an American experimental psychologist who published work in the field of the experimental analysis of behavior.
The Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP) is an assessment and skills-tracking system to assess the language, learning and social skills of children with autism or other developmental disabilities. A strong focus of the VB-MAPP is language and social interaction, which are the predominant areas of weakness in children with autism.
Association in psychology refers to a mental connection between concepts, events, or mental states that usually stems from specific experiences. Associations are seen throughout several schools of thought in psychology including behaviorism, associationism, psychoanalysis, social psychology, and structuralism. The idea stems from Plato and Aristotle, especially with regard to the succession of memories, and it was carried on by philosophers such as John Locke, David Hume, David Hartley, and James Mill. It finds its place in modern psychology in such areas as memory, learning, and the study of neural pathways.
Anthony Charles Catania is an American researcher in behavior analysis known for his theoretical, experimental, and applied work. He is an Emeritus professor of psychology at the University of Maryland, Baltimore County (UMBC), where he taught and conducted research for 35 years prior to his retirement in 2008. He received a B.A. (1957) and M.A. (1958) at Columbia University in Psychology. He received his Ph.D. in Psychology at Harvard University in 1961. He remained at Harvard to conduct research as a postdoctoral researcher in B. F. Skinner's laboratory. Prior to his career at UMBC, he held a faculty position for nearly a decade at New York University (NYU).
References
1 2 Chiesa, Mecca (2004). Radical Behaviorism: The philosophy and the science. Sarasota, Florida: Authors Cooperative. ISBN978-0-9623311-4-5.
↑ It is notable that Skinner did do Verbal Behavior related research, for example the statistical analysis of alliteration in Shakespeare, as well as his work with the "Verbal Summator" prior to the publication of Verbal Behavior. However, he opted to remove most of the research, he says, because it made the book "unbalanced". This research was also primarily structural in nature, and owed more to Skinner's history as a college English major than it did to his later functional analysis of behavior.
↑ Skinner's analysis of verbal behavior is not specifically a matter of "teaching children how to talk", however he does speculate on this on p. 189 in terms of mands and tacts acquisition by children. I note this because Skinner's Verbal Behavior is widely cited as a template for teaching children language skills although it does not appear to specifically be designed for this task.
↑ Skinner, Burrhus Frederick (1957), Verbal Behavior, Acton, MA: Copley Publishing Group, ISBN1-58390-021-7 p. 187
↑ Normand, M. (2001). "Verbal Behavior: History and Future". The Behavior Analyst Today. 3 (1): 41–55. doi:10.1037/h0099959.
↑ Leigland, S. (2007). "Fifty Years Later: Comments on the Further Development of a Science of Verbal Behavior". The Behavior Analyst Today. 8 (3): 336–46. doi:10.1037/h0100625.
↑ Skinner, Burrhus Frederick (1953). Science and human behavior. Mcmillon. ISBN978-0-02-929040-8.
↑ Cautilli, J.D.; Skinner, L. (2001). "Toward a Functional Analysis of "Scientific" Verbal Behavior: A Preliminary Essay". The Behavior Analyst Today. 2 (3): 250–2. doi:10.1037/h0099943.
↑ Guerin, B. (1992). "Behavior analysis and the social construction of knowledge". American Psychologist. 47 (11): 1423–33. doi:10.1037/0003-066X.47.11.1423.
↑ Chomsky, A. Noam (1959). "A Review of Skinner's Verbal Behavior". Language. 35 (1): 26–58. doi:10.2307/411334. JSTOR411334. Retrieved 2014-08-26., Repr. in Jakobovits, Leon A.; Miron, Murray S. (eds.). Readings in the Psychology of Language. New York: Prentice-Hall. pp.142–143.
↑ Frederick J. Newmeyer, The Politics of Linguistics (1986), ISBN0-226-57720-1, p. 73.
↑ Greer, R.D. (2006). "The Evolution of Verbal Behavior in Children". Journal of Speech-Language Pathology and Applied Behavior Analysis. 1 (2): 111–50. doi:10.1037/h0100194.
↑ Cautilli, J.D.; Hantula, D.A. (2004). "Defining The Verbal Specialist: An Adaptive-Evolutionary View of Deception and Counter-Control". The Behavior Analyst Today. 5 (2): 204–14. doi:10.1037/h0100032.
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