JOURNAL OF APPLIED BEHAVIOR ANALYSIS 1997, 30, 533±544 NUMBER 3(FALL 1997) BEHAVIORAL CUSPS: A DEVELOPMENTAL AND PRAGMATIC CONCEPT FOR BEHAVIOR ANALYSIS JESUÂ S ROSALES-RUIZ UNIVERSITY OF NORTH TEXAS AND DONALD M. BAER UNIVERSITY OF KANSAS Most concepts of development explain certain behavior changes as products or markers of the invariable succession of emerging periods, stages, re®nements, or achievements that de®ne and order much of an individual's life. A different but comparable concept can be derived from the most basic mechanisms of behavior analysis, which are its environmental contingencies, and from its most basic strategy, which is to study behavior as its subject matter. From a behavior-analytic perspective, the most fundamental developmental ques- tions are (a) whether these contingencies vary in any systematic way across the life span, and thus make behavior change in a correspondingly systematic way; and (b) whether some of these contingencies and their changes have more far-reaching consequences than others, in terms of the importance to the organism and others, of the behavior classes they change. Certain behavior changes open the door to especially broad or especially important further behavior change, leading to the concept of the behavioral cusp. A behavioral cusp, then, is any behavior change that brings the organism's behavior into contact with new contingencies that have even more far-reaching consequences. Of all the environmental contingencies that change or maintain behavior, those that accomplish cusps are developmental. Behavior change remains the fundamental phenomenon of de- velopment for a behavior-analytic view; a cusp is a special instance of behavior change, a change crucial to what can come next. DESCRIPTORS: development, developmental stages, pivotal behaviors, behavior traps, behavior analysis, behavior change Conceptualizing the development of be- suppose that much behavior develops in havior over the life span has been an endur- obedience to that sequence. And, because ing problem in psychology. Organismic the- the sequence is invariant, it requires an ex- ories postulate an invariable succession of planatory logic, which most often takes the emerging stages, periods, achievements, dif- form of its apparent goal, as if the sequence ferentiations, re®nements, or products; they were self-organizing: The individual is seen as traveling epigenetic roads to uniquely The authors are grateful to Sigrid Glenn, Joel Green- adult stages of development, much like a spoon, Hayne Reese, Wendy Roth, and John Wright for train stopping at various stations before it sympathetic, critical, careful, competent, detailed, and constructive argument; but they should not be held re- reaches its ®nal, always scheduled destina- sponsible for the arguments advanced here. The authors tion, or a butter¯y passing through the em- are also grateful to the National Institute of Child Health bryo-larva-pupa-imago stages to the inevita- and Human Development for research support (HD 18955). ble ¯uttering forth (see Overton & Reese, Address correspondence to JesuÂs Rosales-Ruiz at the De- 1973; Reese, 1991; Reese & Overton, 1970; partment of Behavior Analysis, University of North Texas, Spiker, 1966). Whereas the teleological P.O. Box 13438, Denton, Texas 76203 (E-mail: Ro- sequence implied in such approaches is that [email protected]) or to Donald M. Baer at the Depart- ment of Human Development and Family Life, University an embryo is just a butter¯y's way of making of Kansas, Lawrence, Kansas 66045-2133. another butter¯y, it is equally plausible to 533 534 JESUÂ S ROSALES-RUIZ and DONALD M. BAER argue that a butter¯y is just an embryo's way tant behavior changes have more far-reach- of making another embryo. Perhaps the con- ing consequences than others. Here, we ad- cept of ``development'' is sometimes a way dress that question by describing the concept to ignore an arbitrary half of the evolution- of developmental ``cusps'' (Rosales-Ruiz & ary process. Baer, 1996) and suggesting some criteria for Behavior analysis is different; it has no ``far-reaching.'' comparable guiding metaphor to explain patterns of behavior change throughout the life span. At least, none is intrinsic to its A PRAGMATIC CONCEPT OF present logic. Of course, one or several such DEVELOPMENT FOR metaphors might be added. But that addi- BEHAVIOR ANALYSIS tion would seem apt only if it were done in Consider a cusp as a behavior change that the natural-science style that has guided the has consequences for the organism beyond development of behavior analysis so far. the change itself, some of which may be con- That means it must be more than a meta- sidered important. That requires us to de- phor; the premises justifying it should be velop the criteria of importance. To ap- veri®able. proach those criteria, we must expand the Behavior analysis currently offers its well- de®nition of cusp: We take as axiomatic that known behavior-shaping contingencies as its any behavior change results from changes in basic analytical processes; and it offers them, the interaction between the organism and its so far, without specifying any distinctive, re- environment. What makes a behavior liable patterning of them over the life span. change a cusp is that it exposes the individ- If a concept of development is to be added, ual's repertoire to new environments, es- that concept must posit a reliable pattern of pecially new reinforcers and punishers, new how these contingencies are applied over the contingencies, new responses, new stimulus life span. Stated this way, the possibility of controls, and new communities of maintain- a reliable pattern of behavior-change pro- ing or destructive contingencies. When some cesses over the life span becomes a matter of or all of those events happen, the individual's facts to be determined rather than as a the- repertoire expands; it encounters a differen- ory to be imposed. We can ask whether the tially selective maintenance of the new as application of these contingencies, by nature well as some old repertoires, and perhaps and by people, varies in any systematic way. that leads to some further cusps. We can ask whether the behaviors to which Consider, for example, what can happen they are applied vary in any systematic way, as a result of learning to crawl. The baby and if so, whether that is by nature or by suddenly has increased access to the environ- idiosyncratic societal convention. Discerning ment and its contingencies. Now the baby those kinds of systematic patterns of contin- can get to toys, family, and other things gencies across the life span appears to be an more easily, or can stumble into obstacles, implicit theme of two recent texts that de- all of which produce interactions that will scribe development from a behavior-analytic further shape the baby's behavior. Some of perspective (Novak, 1996; Schlinger, 1995). these interactions initiate the shaping of oth- These texts are oriented toward undergrad- er behaviors that will soon contribute to uate readers; their mission is to show how walking, others will shape responsiveness to traditional developmental topics are amena- visual cliffs (e.g., Campos, Bertenthal, & ble to a behavior-analytic interpretation. But Kermoian, 1992), and still others will pro- we can also ask whether some of the resul- duce a variety of parental contingencies, BEHAVIORAL CUSPS 535 some delighted, some dismayed, that will accurate, ¯uent reading is a cusp. Teach a further shape how much more and how child with developmental disabilities gener- much less of the physical and social environ- alized imitation, and future expansion of the ment will be open to the child's further in- child's repertoire can suddenly and system- teraction. Thus, if walking, safety, and the atically be as explosive as the social environ- immediate next direction of socialization are ment cares to make it, simply by modeling important for that baby at that time, crawl- new skills, not necessarily intentionally. If ing is a cusp. any of that is important, to the child or to This argument does not deny the devel- those responsible for the child, generalized opment of the many small, sequential skills imitation is a cusp. Teach an infant to dis- that culminate in crawling. Perhaps each of criminate between positive parent attention them is a prerequisite for the next, and thus and disapproving parent attention, and you for crawling. But the important point here end the paradoxical reinforcement of inap- is that none of these skills alone suddenly propriate child behavior, which suddenly open the child's world to new contingencies and systematically will alter the child's and that will develop many new, important be- the parents' futures, especially their joint fu- haviors. Instead, each of them opens the tures. If gentle social guidance is important child's world only to the next skill. Their end to the child at that time, then coming under point, crawling, is a cusp. the conventional stimulus controls used nat- By contrast, consider a child who has all urally by almost every parent (and almost the prerequisites for walking, yet continues every subsequent teacher) is a cusp. Give to crawl; an early study by Harris, Johnston, young adults the ®rst sizable, dependable, Kelley, and Wolf (1964) dealt with such a disposable income of their lives, and sud- case. They systematically shaped walking in denly, systematically, and enduringly, new a preschool girl who almost always crawled. sources of teaching will emerge that may al- Walking made it possible for her to partici- ter and expand some of their criteria for and pate in the upright, fast-moving games her some of their practice of what constitutes peers played, which was most of their games. food, housing, transportation, entertain- A host of new interactions typically will fol- ment, travel, family, and responsibility.