The Analysis of Verbal Behavior 1986, 4, 2-9

On the Difference Between Verbal and Nonverbal Behavior

A. Charles CataniaUniversity of Maryland Baltimore County

Language theorists have often proposed lists of the defining properties of language. This accountreviews some of these and offers as an alternative a three-item list consisting of instructionalcontrol, equivalence classes, and autoclitic processes.

The properties that define language havebeen a matter of controversy for centuries.Is language something unitary or is it madeup of separate components that could existindependently? Is its structure determinedby biological constraints or are its dimen-sions arbitrarily shaped by the features ofparticular environments? Is it peculiarlyhuman or can it be demonstrated in otherorganisms? All these and many relatedquestions are relevant to the definition ofverbal behavior.

It is not possible within brief compass toconsider exhaustively the varying accountsof language that have emerged in linguistics,psychology, philosophy and otherdisciplines, or to outline fully the empiricalbases for the many properties that havebeen proposed as its distinguishing features.But the enumeration of its distinguishingfeatures has been a favorite device oftheoreticians of language and provides aconvenient vehicle for reviewing sometreatments. Our survey will indude not onlysome lists proposing properties that definelanguage but also some that itemize whatlanguage is not. But before we consider thelists, a few preliminaries are in order.Language is behavior, and it can be argued

convincingly that it is more appropriate tospeak of verbal behavior than of language(e.g., Skinner, 1957). The former empha-sizes that language is an activity, not a pos-

Preparation of the manuscript was supported in partby NSF Grants BNS82-03385 and BNS85-06724. Anearlier version of this paper was presented in September1983 as a contribution to the NICHD conference ondevelopmental genetics and learning, Leesburg VA. Forreprints, write the author at the Department ofPsychology-UMBC, 5401 Wilkens Avenue, Catonsville,MD 21228.

session. The vocabulary of the present treat-ment will necessarily be variable, however,because the vocabularies will typically bedictated by the terms in the lists to be con-sidered. The vocabulary of communication,for example, involves some assumptionsabout what happens in a verbal episode thatwould not be implicit in a translation to thevocabulary of verbal behavior.

It will be important to distinguish prob-lems of language function from those oflanguage structure; for example, questionsabout the effects of a sentence upon alistener are different from those aboutwhether the sentence is grammatical(Catania, 1973). We will be interested in bothstructure and function. We will be more con-cerned, however, with properties oflanguage that can be characterized inbehavioral terms than with topographicalproperties that have an obvious anatomicalbasis. Details of articulation, phonology,quality of voice and other properties that canbe attributed to features of the human vocalapparatus are important, but for the presentpurposes a more significant concern is thatof defining the functional units of verbalbehavior.Let us now turn to the lists. Miller (1965),

in the context of the psycholinguistics thatgrew out of Chomsky's theories ofgenerative grammar (Chomsky & Miller,1963), offered seven propositions intendednot so much exhaustively to define basicaspects of human language as to serve asreminders of neglected dimensions oflanguage:

1. Not all physical features of speech aresignificant for vocal communication,and not all significant features ofspeech have a physical representation.

2

A. CHARLES CATANIA 3

2. The meaning of an utterance shouldnot be confused with its reference.

3. The meaning of an utterance is not alinear sum of the meanings of thewords that comprise it.

4. The syntactic structure of a sentenceimposes groupings that govern theinteractions between the meanings ofthe words in that sentence.

5. There is no limit to the number ofsentences or the number of meaningsthat can be expressed.

6. A description of a language and adescription of a language user must bekept distinct.

7. There is a large biological componentto the human capacity for articulatespeech.

What are we to make of this list? The firstcharacteristic is undoubtedly common to allvarieties of behavior. Ethological releaserstoo are characterized by critical features, andthe problem of defining classes of behavioris not confined to speech. Surely we wouldagree that while producing the same wordsthe voices of two speakers can differ in manyways. Surely we would also agree that whatwe hear as particular phonemes can be pro-duced in so many ways that we cannotdefine a characteristic physical structure.The problem, however, is not limited to thelanguage domain; it arises in suchphenomena, for example, as the constancyof a melody over transpositions of key anda variety of other perceptual constancies.The next three items are concerned with

meaning. "Inventor of the cumulativerecorder" and "author of Verbal Behavior"do not have the same meaning even thoughthey have the same referent; the word"extinguish" is understood differently ifwhat is said to be extinguished is a responsethan if it is a fire or a population ofdinosaurs; and additional information isneeded to determine whether "They arecontrolling stimuli" is a sentence about en-vironmental variables or about experi-menters. The point of these three items isto suggest that language cannot be dealtwith solely in terms of associations orstimulus-response connections of some sort.The first two make the point with respectto semantics and the last with respect tosyntax. In various ways they each say thatcontext matters in language. Few contem-

porary behavioral treatments, however, dealwith the structure of language as arisingmerely from simple sequential dependen-cies created by conditioning, and theseitems, like the first, have parallels in nonver-bal phenomena, where context also matters(it is implicit, for example, in the functionalrather than topographical definition ofoperant classes).The fifth item asserts that productivity, the

generation of novel sentences or meanings,is a feature of language, but it is silent as towhether productivity is exclusive tolanguage. That is just as well, becausenonverbal behavior can be productive (e.g.,Fentress, 1978; Catania & Cerutti, in press),and productivity therefore is not a sufficientdefining property of language even thoughit might be significant in its contributions toimportant consequences of language. Just asa human may utter a sentence that has neverbeen uttered before, a bird may fly a con-voluted path that has never been flownbefore. The integration of the componentresponses of both performances involvescomplex coordinations; there is a grammarof flight as well as a grammar of language.Even the quantitative problem of produc-

tivity has been exaggerated. For example, thenumber of possible ten-word utterancesbased on a vocabulary of two thousandwords (Basic English has a vocabulary of 850words) is 2x1013. But allowing for fewer thansixty utterances per day, this is the numberthat would be uttered in a year by a popula-tion of one billion speakers of English (notfar from the number in the present humanpopulation of the world). This example doesnot make allowances for variations in sen-tence length, but that variable is balancedby the fact that only a very small proportionof the possible utterances would qualify asgrammatical or would approximate gram-maticality closely enough to occur in humandiscourse. Thus, it is likely that novel sen-tences make up only a small part of humanspeech. This is not to say that productivityis unimportant; rather, it is to say that thenonproductive aspects of language must notbe ignored even if they seem to hold littleinterest for psycholinguists.

Miller's sixth item has served as a rally-ing cry. It seems to resurrect the distinctionbetween learning and performance, trans-formed to that of competence and per-

4 VERBAL AND NONVERBAL BEHAVIOR

formance. For Miller, this is a call for theconstruction of performance models. Inother words, it is a prescription for thestudent of language, and says little aboutlanguage and language users. It is perhapsequivalent to saying that organisms shouldnot be confused with their behavior. But wetend not to mix up responses like leverpresses and key pecks with individualorganisms like rats and pigeons, and wetherefore should be able to distinguish par-ticular utterances from properties of lan-guage that characterize populations ofutterances.And the seventh item is a truism. Human

language is presumably a product of evolu-tion. But we are given no hint by this itemof where we might search for continuitieswith nonverbal behavior, or even of thepossibility that human language is not anunanalyzable entity but rather a unique con-junction of distinct behavioral processes.

Miller's list identifies properties oflanguage that have been overlooked in someearlier psychological treatments andacknowledges its complexities, but in theend it says little about what distinguishesverbal from nonverbal behavior. A more am-bitious list is Hockett's (1958, 1960, 1963; cf.Linden, 1981; Paivio & Begg, 1981). Hisoriginal list of seven design features oflanguage has expanded to sixteen. Let usbegin with the seven, noting that Hockettremarks of these seven properties that they"do not recur, as a whole set, in any knownnon-human communicative system,although individually some of them do"(Hockett, 1958, p. 574):

1. Interchangeability. The members of alanguage community can both transmitand receive; typically speakers canbecome listeners and vice versa.

2. Specialization. The effects of languageare not physical consequences oftransmitting; a spoken word is notanalogous to a blow to the body.

3. Displacement. Language can refer toremote objects and events; we canspeak of Thomdike and Pavlov withoutever having seen either of them.

4. Productivity. Language allows both syn-tactic and semantic novelty; we candescribe a bird with cocker-spaniel earseven if one has never existed.

5. Cultural transmission. Language is

maintained by instruction rather thanby genetic variables; children learn thelanguage of the community even if itis different from that of their parents.

6. Arbitrariness. The relation betweensigns and their referents does notdepend on shared properties; thewords "red" and "green" have nocolor.

7. Duality. Language is built of hierarch-ical elements such as phonemes, let-ters, syllables, and words; the units atone level are created by various ar-rangements of the units at anotherlevel.

As Hockett would agree, interchange-ability and specialization are not restrictedto phenomena of verbal behavior. Anyinteraction between organisms, includingcombat between members of differentspecies, may involve reciprocity, andspecialization in Hockett's sense is charac-teristic of many of the releasers studied byethologists.Displacement involves behavior with

respect to events distant in time or space,and is involved in the study of remember-ing, whether verbal or nonverbal. What isremembered, however, is more accuratelydescribed as our behavior with respect topast events than as the past eventsthemselves (e.g., Catania, 1984, Chapter 12).It is important that we are able to speak ofabsent and even of nonexistent things, butdisplacement can come about in varied waysand a taxonomy of the phenomena thatqualify as instances would therefore beuseful. The problem of saying what hap-pens when we speak of remote events mightbe more easily resolved after we have dealtwith the more fundamental one of sayingwhat happens when we speak of currentones.We have already spoken of productivity.

It is sufficient to note here that novelutterances can come about as a consequenceof novel combinations of environmentalevents. If a child has learned to call certaincolors purple and certain creatures cows, itwould be no surprise to hear the child say"purple cow" in the presence of a bovineof relevant color.Cultural transmission does not demand

elaboration. Arbitrariness and duality,however, are properties of language that are

A. CHARLES CATANIA 5

not obviously shared by nonverbal behavior.They might therefore be regarded as themost significant items in Hockett's list. Arbi-trariness might be a condition for the com-bining units that characterize duality, andlanguage would at best be limited to a smallvocabulary if it did not involve recombina-tions of a small population of units.Hockett's later longer lists add some

features specific to the vocal properties ofhuman speech: the vocal-auditory channel (8);the broadcast transmission of vocal signals andas a corollary their directional reception (9);the rapid fading of these signals, with impli-cations for channel capacity and for memory(10); and complete feedback, in that the speakeras well as the listener receives the signal(11). These features likely are phylogenic inorigin, but they call more for anatomical,audiological and phonological than forbehavioral analyses.Four of Hockett's five remaining features

are derivative of those in the shorter list. Thesemanticity of language (12) is implicit in botharbitrariness and displacement. Its discrete-ness (13) implies distinctive features and isimplicit in duality of patterning. The pos-sibility of prevarication (14) depends onseveral of the other categories, and is notlimited to verbal behavior (cf. Dawkins, 1976,Chapter 6, on deceptive mimicry). Andleainability (15) is implicit in culturaltransmission. The remaining feature, reflex-iveness (16), states that language must allowcommunication about communication. Aprerequisite for such a property of languageis that language users be able to discriminateproperties of their own behavior. This prop-erty is encompassed by autoclitic processesin the analysis of verbal behavior (Skinner,1957) and by the concept of deixis inpsycholinguistics (e.g., de Villiers & deVilliers, 1974). With respect to this property,we will here note only that both inter-changeability (1) and the complete feedback(11) provided by the vocal modality may beessential to the evolution of reflexivity. Wewill return later to this property of verbalbehavior.The last of our sample of prior lists is

Osgood's (1980), whose sixteen definingcharacteristics of language are supplementedby ten others that should not be regardedas defining criteria. Osgood's sixteen posi-tive items partially overlap Hockett's.

Osgood distinguishes language in generalfrom human language in particular. Theformer must involve:

1. Recurrent events. A language mustconsist of identifiably different and nonran-dom forms.

2. Reciprocality. This item is equivalent toHockett's interchangeability.

3. Pragmatics. Verbal behavior must haveconsequences; more specifically, itmust affect other behavior, eitherverbal or nonverbal.

4. Semantics. The forms of the languagemust be nonrandomly related to theirreferents.

5. Syntax. The forms of the languagemust combine in orderly rather thanrandom ways.

6. Productivity. This productivity issimilar to Hockett's; Osgood empha-sizes that the novel productions mustsatisfy the constraints of his first fiveitems.

We have already dealt explicitly with mostof these items, and the ones that remain areimplicit in Miller's and Hockett's lists. Themajor difficulty is that semantics plays animportant role and yet is undefined. Clearlythere exist relations between language unitsand events in the world, but what does itmean for something to have a referent?Beyond these properties of language in

general, Osgood offers five structural andfive functional characteristics specific tohuman language. Of the structural charac-teristics, all except item 10 are equivalent toitems in Hockett's list:

7. The vcal-auditory channel.8. Broadcast transmission and directional

reception.9. Evanescence in time (rapid fading).

10. Integration over time (presumably aconsequence of 9).

11. Prompt feedback.Integration over time is significant because

of its implications for remembering. Thebeginning of a sentence is past when onehears its end, and yet one's response to theend may often depend on the beginning.Nevertheless, as demonstrated by the chim-panzee language of plastic chips developedby Premack (1970), at least some languagefunctions can be established withnonhuman organisms when the languagesystem does not impose aburden on remem-

6 VERBAL AND NONVERBAL BEHAVIOR

bering. For this reason, integration over timequalifies as a property of human languagebut not as a defining property of language ingeneral.Osgood's five functional characteristics

correspond to various items in Hockett's listor to derivatives of those items:

12. Semantic arbitrariness. Semantic unitsare not iconic.

13. Discreteness ofsymbols. Discontinuitiesmark the boundaries of semantic units.

14. Hierarchical organization. The embed-ding of units within units is directional;words are composed of phonemes,and not vice versa.

15. Componential organization. As inHockett's duality, a unit at one level(e.g., a phrase) can be exhaustivelydecomposed into units at another level(e.g., words).

16. Transferral via learning. Humanlanguages depend on culturaltransmission.

In the remainder of his list, Osgoodexcludes the following ten characteristics asnecessary defining properties of language:

1. Propositionalizing. Language does notconsist of propositions; it does notdepend on testability for truth orfalsity.

2. Prevarication. Language does not implya capacity for lying.

3. Reflexiveness. Language need not havelanguage itself as a referent.

4. Learnability. Some languages may belearnable only by restricted popula-tions or only at certain ages.

5. Translatability. A particular languageneed not be translatable into any otherparticular language.

6. Particular selection and combination rules.Syntactic and phonetic rules that arecommon to many human languagesare nonetheless statistical rules ratherthan language universals.

7. Progressive differentiation. Languageschange (as whenwords that more andmore finely differentiate regions of thespectrum are added to a language) buthuman languages would remainhuman languages even if their evolu-tion were halted.

8. Least effort. The inverse relation be-tween size of language units and theirfrequency of use is a statistical proper-

ty of language that may sometimes befound in nonverbal behavior as well.

9. Affective polarity. Human languages arecharacterized by semantic polarity(e.g., good, strong, active versus bad,weak, passive) with unmarkedpositive and marked negative forms(e.g., happy, unhappy but not sad, un-sad), but cases in which thesepolarities were eliminated or reversedwould not then be disqualified ashuman languages.

10. The greater diversity of positive thannegative linguisticforms. As for affectivepolarity, the elimination or reversal ofthese regularities ofhuman languageswould not be a disqualifyingcharacteristic.

There is some consistency to the lists wehave considered (e.g., Hockett and Osgoodon productivity and on feedback) but thereare also disagreements (e.g., Hockett andOsgood on prevarication and on reflex-iveness). We could now examine the variousspecific cases. A more appropriate way toconclude this survey, however, is with twomore lists. The first and longer list (sevenitems) asserts what language is not; the sec-ond offers only three features of language asits critical properties. A brief consideration ofsome implications of those properties thenbrings this account to a close.

1. Language is not defined by its struc-ture, syntactic or otherwise. Structureis a property that language shares withnonverbal behavior. Locomotion, forexample, also has a grammar; the coor-dination of an insect's hind leg with itsother legs, like the turn of a phrase ina sentence, occurs under constraints ofcontext (e.g., Gallistel, 1980).

2. Language is not defined by produc-tivity. Productivity occurs when dif-ferent dimensions of behavior arejointly occasioned by different con-trolling events, as when a physicalobject determines the noun and anaction determines the verb of asentence. Productivity is to beunderstood in terms of novel conjunc-tions of events, but these events neednot be verbal.

3. Language is not computation. Thisassertion is not intended as a restate-ment of the argument that verbal be-

A. CHARLES CATANIA 7

havior is not generated as a sequenceof stimulus-response units, althoughit is consistent with it. Rather, its pointis that verbal behavior is not a productanalogous to a calculated or derivedsolution to a problem. Languagesometimes makes certain types ofproblem solving possible, but theutterance of a sentence is not a solutionto a problem of expression. Rules areinstances of behavior, but verbalbehavior itself is more likely to be con-tingency-shaped than rule-governed(Skinner, 1966).

4. The discreteness and hierarchicalorganization of its units permits thegeneration of multitudinous verbalforms, but language is not defined bythe sheer quantity of verbal units.

5. Displacement has significant conse-quences inhuman language but is notcritical to its definition. It would be aserious deficit to be able to speak onlyof concrete objects actually present,but the speaker would remain aspeaker of the language nonetheless.

6. Language is not a tool; it is not a vehi-cle of truth or an instrument of reason.This is not to deny that verbalbehavior has consequences. Given theprevalence of the language of "using"words, however, it is useful to recallthat words are instances of behavior.

7. Language is not communication; it isnot a means of conveying or express-ing ideas, feelings or emotions. Themetaphor of communication is per-vasive but misleading. It is embeddedin everyday talk, as when we say thatwe "put ideas into words" or "getsomething across," or as when wespeak of words as "carrying mean-ing" or writings as "packed withinformation" (cf. Lakoff & Johnson,1980; Reddy, 1979). Yet "idea" and"meaning" are not well-definedterms, and even "information" rarelyimplies the quantifiable stuff of infor-mation theory. The magnetic patternsthat correspond to a tape-recordedvoice have no meaning unless some-one listens to the recording; the mean-ing is not waiting to be released fromthe tape. If anything is transmitted inlanguage, it is the verbal behavior

itself; in listening and reading ourown behavior recreates some featuresof the verbal behavior of those whoconstitute our verbal community. Inlanguage, in other words, behaviorreplicates itself.

What then is special about language? Onlya small proportion of the items in the severalpreceding lists are concerned with the func-tions of language, and even those that areso concerned sometimes deal with functionsthat are suspect (e.g., communicating). Letus therefore consider our final list:

1. Instructional control. The central func-tion of language is instructional con-trol: language is a way in which oneorganism changes the behavior ofanother. This function, captured bythe distinction between rule-governedand contingency-shaped behavior(Skinner, 1966), implies that in-structed behavior sometimes will berelatively insensitive to contingencies,or sensitive to contingencies onlyindirectly, through the mediation ofverbal behavior.

2. Equivalence classes. Discriminative con-trol is unidirectional: a stimulus setsthe occasion on which respondingmay have consequences. For example,the relation between a red traffic lightand stepping on the brakes is notreversible. That between the red lightand the word "stop," however, is.Symmetries exist in the relationsamong verbal responses and nonver-bal events. We can produce a pencilupon hearing the word "pencil" andwe can produce the word "pencil"upon seeing this writing implement.These kinds of equivalences are whatmake verbal behavior symbolic.Unlike nonverbal events, verbalevents function both as stimuli and asresponses (lever presses and keypecks are not analogously inter-changeable with lights and tones).Verbal behavior is characterized byand the concepts of meaning andreference are to be understood interms of such equivalences (cf. Sid-man, Rauzin, Lazar & Cunningham,1982).

3. Autoclitic processes. Verbal behaviorcannot exist in the absence of dis-

8 VERBAL AND NONVERBAL BEHAVIOR

criminations of one's own behavior(the reflexiveness of Hockett andOsgood; cf. Catania, 1980). Verbalbehavior is autoclitic when it is builtupon and modifies the effects of otherverbal behavior (Skinner, 1957). Forexample, saying "I am reluctant toassert that" modifies the effects ofsaying "language is innate"; similareffects can be produced by insertingthe word "not." This modifyingautoclitic verbal behavior cannot oc-cur unless the speaker candiscriminate the conditions that con-trol the utterance "language is in-nate." Because the important dimen-sions of words like "is" and "if" and"not" are autoclitic rather thanlogical, a propositional character oflanguage based on functional ratherthan logical relations is implicit inautoclitic processes.

As has already been argued here, thesimplest and most obvious function of ver-bal behavior is instructional control: oneorganism can, by talking to another, changethe other's behavior. Language is a way inwhich one organism can make another dosomething. Once both organisms are talk-ing, then one can instruct what the othersays as well as what the other does (Catania,Matthews & Shimoff, 1982; cf. Lowe, 1979).Verbal behavior likely followed from theevolution of social control, in a progressionfrom vocal releasers to varied verbal func-tions shaped by social consequences(Catania, in press). It is consistent with thisview that instructed human behavior isinsensitive to its environmental conse-quences, relative to behavior shaped by con-tingencies. When you do what you are told,your behavior is controlled by the instruc-tion rather than by its natural consequences.Uninstructed behavior, not influenced bylanguage, is most likely to be in close touchwith environmental events (Matthews,Shimoff, Catania & Sagvolden, 1977.)Instructions are conceived here more

broadly than as statements of command ordirection. Giving definitions and statingfacts are instructions with respect to thelistener's future verbal behavior. Speakingaffects the behavior of others whether or notthe speech has the grammatical character ofthe imperative.

The instructional characteristics of verbalbehavior are not independent of equivalenceclasses and autoclitic processes. To the ex-tent that instructional control allows inter-changeability, the speaker will sometimesfunction as the listener and vice versa, andthe evolution of equivalence classes willfollow as a matter of course. Equivalenceclasses are linked to instructional control byway of the correspondences that mustnecessarily develop in the reciprocities of thespeaker's and the listener's behavior. Toestablish correspondences between sayingand doing is to establish equivalencesclasses (e.g., Paniagua & Baer, 1982).

Further, given that instructions may berepeated by a listener, listeners mustdiscriminate themselves from others as thesources of verbal behavior. It is one thing torespond to what someone else has said; itis another to respond to one's own repeti-tion of the other's utterance. Discriminationof the sources of instructional control mayhave marked the beginnings of autocliticprocesses, from which follow those pro-cesses we speak of as metalanguage(language about language) and conscious:ness or self-awareness (cf. Jaynes, 1977).Instructional control, equivalence classes

and autocitic processes are dimensions ofverbal behavior that are ripe for behavioranalyses. All are presumably products of theevolution of human behavior. Will it bepossible to explore individual differences insusceptibility to instructional control, or inthe breadth or number of equivalenceclasses that can be established, or in rangesor types of autoclitic processes? If such dif-ferences emerge, what will be their func-tional significance? Most important, to whatextent will an analysis of such differences tellus something about the interdependence ofthese three dimensions of verbal behavior?Is any one a prerequisite for one or both ofthe others, or do all grow out of other morefundamental behavioral processes? Themost substantial progress will be madewhen we can move on from analyses ofthese separate dimensions to analyses oftheir relations and interactions in develop-ing and in established verbal behavior.

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