Guest post by Dr. Ciobha McKeown
Dr. Ciobha McKeown is an Assistant Professor at California State University, Sacramento, and director of the Infant, Toddler, and Life Skills (ITLS) Lab. Previously, she was a Research Assistant Professor at the University of Florida, where she developed a short-term early intervention program. Across the past 15 years, she has been fortunate to learn from the neurodiverse and neurotypical children she has supported. Much of her research has been inspired by her clinical history. As such, her research interests run the gamut of early intervention, verbal behavior, social skill, and, thanks to Zain, how biological and environmental factors influence development.
It was a warm, sunny day in Florida—though, more likely, it was a hot, humid day—when I met Zain (note: Zain is the pseudonym used in McKeown et al. [2024]). Zain was the first six-month-old infant I had the pleasure of supporting, and over the next nine months, I had the privilege of watching him grow alongside his family. His family sought support because he was not yet meeting severall milestones outlined by the Centers for Disease Control and Prevention (CDC, n.d.).
As many behavior analysts would have, I started with an assessment. I wanted to be thorough and thoughtful, so I began with a conversation with his mom about her concerns. From there, we creatively arranged opportunities to assess Zain’s skills in relation to early developmental milestones. Based on that assessment, we concluded that Zain was delayed in several areas of early communication. He was not yet responding to sounds by making sounds, stringing vowels together when babbling, or making consonant sounds. Around that time, I had a humbling conversation with a speech-language pathologist colleague. She told me that, at Zain’s age, we might expect approximately five vocalizations per minute. I went back to Zain’s assessment data. Across multiple assessment sessions, including sessions conducted over Zoom in his home, Zain rarely vocalized. In some sessions, he vocalized only once. In others, he did not vocalize at all. I knew the data were compelling, but I did not yet have the skill set to interpret them fully.
At that point, I had been supporting children with autism and other developmental disabilities for almost ten years. I was trained to look carefully at the environment, identify teachable responses, arrange consequences, and build repertoires that matter. I had seen children learn to mand, imitate, play, tolerate delays, and participate more fully in family and school routines. I thought I understood what it meant to support early development. Working with an infant forced me to reconsider that assumption. It also made one thing impossible to ignore: the developmental literature.
To best support Zain, I recognized that I needed a better understanding of the context in which his repertoires were emerging: how biological maturation and sensitivity to operant contingencies might influence what responses appeared, how they changed, and how they related to one another over time.
Behavior Change, Time, and the Problem of Waiting
Developmental psychology is broadly concerned with how behavior changes across the lifespan. Bijou (1968) described the field as the study of progressive changes in interactions between a biologically changing organism and changing environmental events. It has two broad goals: (a) to describe age-related changes as accurately as possible and (b) to explain the process of change.
Those goals should feel familiar to behavior analysts. We may use different terms, but we also care about how behavior changes over time. We ask how prior histories, current environments, biological conditions, and arranged contingencies influence what a person does now (Bijou & Baer, 1961). In that sense, behavior analysis and developmental psychology have overlapping goals.
Baer (1973) made a similar point when he described developmental research as emphasizing three features:
- Behavior change. Both developmental psychology and behavior analysis are concerned with how behavior changes over time.
- The time course of behavior. Developmental psychology often organizes behavior change across age. Behavior analysts may not treat age as an explanation, but we do care about learning history.
- Waiting along that time course. This is where the fields can diverge. If development is treated as something that simply unfolds with age, it can become easy to wait for a child to become ready, for a milestone to arrive, or for a skill to emerge. Baer’s “why wait?” question pushes against that conclusion. If behavior changes through interactions among the child, the environment, and experience, then time does not have to be empty. Time can be filled with meaningful learning opportunities.
That was the perspective I brought to Zain. Developmental psychology helped me understand why his early communication mattered in relation to his age and prior history. Behavior analysis helped me ask what could be arranged next. I did not need to choose between watching development and teaching. The better question was how to use what developmental psychology helped me notice to arrange better learning opportunities.
Using Development as Context, Not a Waiting Room
I started to think differently about what it meant to arrange support for Zain. Initially, I tried to strengthen vocalizations by arranging caregiver attention contingent on Zain’s vocal behavior (Neimy et al., 2020). But caregiver attention was not a sufficient reinforcer for Zain’s vocalizations.
I observed what Zain’s reinforcers were. Zain was already reaching, orienting, moving toward preferred items, and beginning to climb when something he wanted was out of reach. So, we taught a response that could produce access to those reinforcers. Manual signs allow children to produce observable, differentiated responses before speech has been fully developed (Thompson et al., 2007). We taught Zain to sign for “help” using simple behavioral techniques: modeling, physical prompting, prompt delays, and reinforcement (McKeown et al., 2024).
Although the techniques were simple, we observed collateral increases in motor imitation, manding with eye contact, delivering difficult tasks to a caregiver when asking for help, and vocalizations. These changes likely reflected features of the teaching arrangement. For example, our teaching arrangement resembled imitation training: Zain observed his caregiver’s modeled sign, produced a similar motor response (either independently or through physical prompting), and accessed reinforcement (assistance). Caregivers also modeled the sign while saying “help,” repeatedly pairing the vocal model with access to preferred items. Teaching a request for “help,” therefore, arranged a context in which multiple communication responses, not only the manual sign, could contact reinforcement. Importantly, we taught Zain a discriminated mand for help, which is listed as a 15-month-old milestone. That is, in the spirit of “why wait?” we helped support the development of an earlier communication repertoire.
Watching Play Change Over Time
I also watched Zain’s play refine over time. He was no longer the infant who primarily mouthed toys. He was now running around with his “dig digs” (his name for toy cars). At some point, I realized we had captured much of that change on camera, and those videos became the basis for a descriptive analysis of Zain’s play development that my undergraduate research assistant, Carley Smith, presented at an ABAI convention (Smith et al., 2022).
Belsky and Most (1981) used a cross-sectional developmental design, comparing infants at different ages, and showed that forms of play were correlated with age: simpler forms of object engagement were more common earlier, whereas more complex forms of play were more common later. However, cross-sectional age differences should be interpreted carefully; they show differences between age groups, not necessarily how any one child changes over time (Kraemer et al., 2000).
Using the developmental literature’s operational definitions (side quest for behavior analysts: developmental psychology may benefit from a tutorial on developing more precise operational definitions), we coded 9 months of videos of Zain’s play. What surprised me was that Zain’s longitudinal graph nearly replicated the patterns observed across cohorts of infants in Belsky and Most (see Figure 1 in their publication as a comparison).
Baer’s (1970) age-irrelevant concept of development helped me think through what that overlap might mean. Age may organize developmental patterns, but as a behavior analyst I am still curious about what variables are changing with age. From a behavior-analytic perspective, age-related patterns may reflect several things:
- Contingencies may commonly occur around certain ages. If a skill overlaps with age, it may be because similar learning opportunities, caregiver responses, or routines tend to occur around that time.
- Sequences may reflect the ease of shaping later responses. Developmental psychologists often describe skills as developing in a particular order. From a behavior-analytic perspective, those sequences may reflect that some forms of play are easier to shape after simpler forms of object engagement are already occurring.
- Sequences may also reflect culturally-selected expectations. The goals selected by caregivers or other behavior-change agents are likely influenced by cultural practices, including expectations about what infants should do with toys at different ages.
- Time matters, but not only as age. Development takes time, but the relevant unit may be accumulated opportunities to contact systematic learning contingencies.
In our graph, age was not treated as the cause of Zain’s play. Rather, age helped us organize repeated observations of his behavior over time. Still, the overlap between Zain’s longitudinal graph and the patterns Belsky and Most observed across groups of infants was fascinating. To me, it suggested that biological maturation and experience with operant contingencies may interact in orderly ways during play development.
Final Takeaways
I want to give developmental psychology some leeway. Age is parsimonious. It allows researchers to organize large patterns of behavior change without tacting every prerequisite skill, learning history, and contingency involved. The problem is not using age to describe developmental patterns; the problem is treating age as the explanation for those patterns (Baer, 1970).
For behavior analysts, age can be a starting point. It can help us notice patterns, delays, and possible cusps. But then we still have to ask what responses are available, what consequences matter, and what conditions can be arranged now.
With that in mind, I see a few useful directions for behavior analysts:
- Read developmental literature to assess and teach behavioral cusps.
If our goal is to teach responses that produce broader, generative behavior change, then we need to know which responses tend to open access to new contingencies (Rosales-Ruiz & Baer, 1997). Developmental psychology can help identify potential cusps that behavior analysts can then directly assess. - Use developmental psychology to improve ecological validity.
Developmental research can help us understand what typically occurs in children’s everyday environments. That information can help behavior analysts design teaching arrangements that are more natural, less intrusive, and more closely aligned with the contexts in which repertoires usually develop. - Alternatively, behavior analysts could conduct more descriptive analyses.
If we want to understand early development, we need to spend more time watching what happens before intervention. Descriptive analyses can help us identify the responses children already use, the consequences those responses contact, and the naturally occurring arrangements that may support emerging repertoires. - Relatedly, we need to assess neurotypical development more often.
Assessments with neurotypical infants and young children could help identify possible prerequisite skills for the generative repertoires we aim to teach. - Study the interaction between maturation and contingencies.
For behavior analysts, one important question is how biological maturation changes sensitivity to operant contingencies. Understanding that interaction could help us arrange teaching opportunities that are better suited to the child’s current repertoire (Bijou, 1968; Pelaez & Novak, 2024).
In sum, verbal behavior matters. So does development. Behavior analysis and developmental psychology do not need to be rivals; they could, in fact, be good friends.
References
Baer, D. M. (1970). An age-irrelevant concept of development. Merrill-Palmer Quarterly of Behavior and Development, 16(3), 238–245. http://www.jstor.org/stable/23082475.
Baer, D. M. (1973). The control of developmental process: Why wait? In J. R. Nesselroade & H. W. Reese (Eds.), Life-span developmental psychology: Methodological issues (pp. 185–193). Academic Press. https://doi.org/10.1016/B978-0-12-515650-9.50015-0
Belsky, J., & Most, R. K. (1981). From exploration to play: A cross-sectional study of infant free play behavior. Developmental Psychology, 17(5), 630–639. https://doi.org/10.1037/0012-1649.17.5.630
Bijou, S. W. (1968). Ages, stages, and the naturalization of human development. American Psychologist, 23(6), 419–427. https://doi.org/10.1037/h0026479
Bijou, S. W., & Baer, D. M. (1961). Child development: A systematic and empirical theory. New York: Appleton-Century-Crofts.
Centers for Disease Control and Prevention. (n.d.). Important milestones: Your baby by six months. https://www.cdc.gov/ncbddd/actearly/milestones/milestones-6mo.html
Kraemer, H. C., Yesavage, J. A., Taylor, J. L., & Kupfer, D. (2000). How can we learn about developmental processes from cross-sectional studies, or can we? The American Journal of Psychiatry, 157(2), 163–171. https://doi.org/10.1176/appi.ajp.157.2.163
McKeown, C. A., Smith, C. E., Vollmer, T. R., Lloveras, L. A., & Peters, K. P. (2024). Teaching an infant to request help. The Analysis of Verbal Behavior, 40(1), 53–62. https://doi.org/10.1007/s40616-023-00198-9
Neimy, H., Pelaez, M., Monlux, K., Carrow, J., Tarbox, J., & Weiss, M. J. (2020). Increasing vocalizations and echoics in infants at risk of autism spectrum disorder. Behavior Analysis in Practice, 13, 467–472. https://doi.org/10.1007/s40617-020-00413-2
Pelaez, M., & Novak, G. (2024). Language development and behavioral systems. The Psychological Record, 74, 555–572. https://doi.org/10.1007/s40732-023-00578-6
Rosales-Ruiz, J., & Baer, D. M. (1997). Behavioral cusps: A developmental and pragmatic concept for behavior analysis. Journal of Applied Behavior Analysis, 30(3), 533–544. https://doi.org/10.1901/jaba.1997.30-533
Smith, C. E., McKeown, C. A., Vollmer, T. R., & Peters, K. P. (2022). Descriptive assessment of play development in an infant at risk for autism [Poster presentation]. 48th Annual Convention of the Association for Behavior Analysis International, Boston, MA, United States.
Thompson, R. H., Cotnoir-Bichelman, N. M., McKerchar, P. M., Tate, T. L., & Dancho, K. A. (2007). Enhancing early communication through infant sign training. Journal of Applied Behavior Analysis, 40(1), 15–23. https://doi.org/10.1901/jaba.2007.23-06