Escaping Our Research Silos in Rising to the Challenge of Human Psychology


Dear blog reader, we (Colin Harte and Dermot Barnes-Holmes, pictured below at Colin’s PhD defense) are delighted to be hosting the Symbolic Language and Thought blog series. We would first like to acknowledge the hard work and the dedication of the previous hosts of the blog series, Ruth Anne Rehfeldt, Ian Tyndall and Louise McHugh. We hope that we can maintain the high standards they have set for the blog in recent years.

In deciding how to take the blog series forward, we thought it would be important to reflect upon how behavior analysis has and is approaching the topics or domains of symbolic language and thought. In doing so, we could see that there was much to be proud of and also to be excited about going forward. But at the same time, we could see that a worrying trend had emerged within the field. Specifically, although some really great work was being done in both basic and applied research groups and settings, a certain “silo” mentality has taken hold. As just one example, folks working in relational frame theory (RFT) appeared to have created a sub-field in which they cite mainly their own work and have developed their own (some argue, impenetrable) technical-ese. And in making this claim, we are pointing the finger directly at the authors of the current blog, and we are indeed guilty as charged!

In taking over the current blog series, we therefore saw this as an ideal opportunity to offer a mea culpa and to do our best to “heal the wounds” so to speak. In this context, we intend to build the blog posts around the theme of collaboration and cooperation among the various individuals and groups who have done and are doing work that is directly relevant to the domains of symbolic language and thought. In doing so, we will be inviting a range of folks from the different “silos” to leave their weapons at the door and tell their research stories in a manner that will facilitate ongoing collaboration, or at least genuine mutual interest in each other’s basic and applied research efforts.

In our view, we are too small a field to divide ourselves into even smaller sub-groups, and from what we can see there is indeed tremendous overlap in the research that we are all doing, even if we often use different terms and concepts to talk about the behavior we are studying. Critically, we all seem to be aiming to develop a behavior-analytic, monistic, and naturalistic account of human language and thought that is devoid of mentalistic theorizing and speaks directly to practical concerns in educational, clinical, organizational, and other settings. 

In calling for a more collaborative or cooperative approach we are not suggesting that we all have to agree with each other in an anodyne manner and engage in empty gestures of mutual respect. Debate and disagreement should be welcome but only if it serves to bring greater clarity or progress for the field. An excellent example of the type of debate we are thinking of here may be found in the exchange between Willard Day and Murray Sidman in the series of letters between the two that Murray (1994) published in his volume, Equivalence Relations: A Research Story. If nothing else, the letters are worth reading to help current researchers appreciate the “giants’ shoulders” upon which we all stand as we continue to wrestle with human language and thought from a behavior-analytic perspective. 

In recognizing that we (behavior analysts interested in verbal behavior) are wrestling with symbolic language and thought, it may be useful to suggest a common idea or assumption around which we can build our efforts. One option in this respect could be the idea that humans are essentially unique in that we may be described as a symbolic species (Deacon, 1998). If we add to this the modern evolutionary science argument that evolution operates across multiple levels, one of which is the symbolic inheritance stream (e.g., Sloan-Wilson et al., 2014), this may help to bring some clarity to our collaborative research efforts. For example, evolutionary science argues that there are three key dimensions involved in evolutionary processes; variation, selection, and retention, and these operate within each level of evolution, including the symbolic (e.g., Hayes et al., 2020). If that is the case, the question fairly shouts out — what are the units of symbolic behavior that vary, that are selected, and are retained? In RFT there has been a recent emphasis on connecting the account to evolution science and providing a hyper-dimensional multi-level framework that aims to identify the very units of symbolic behavior that vary, get selected, and are retained (see Barnes-Holmes, et al., 2017; Harte & Barnes-Holmes, in press). Similarly, Verbal Behavior Development Theory (VBDT; Greer & Speckman, 2009), has placed the account within the wider context of evolution science and defined what are clearly important behavioral cusps, such as unidirectional naming, bi-directional naming, and incidental naming, that could be seen as involving variation, selection and retention. Of course, the foci and technical details of RFT and VBDT differ in many ways, but the overarching concern with identifying the units of symbolic behavior (which vary, are selected, and retained) highlights a shared ground of interest that may serve to facilitate cooperation and collaboration among currently separate research silos.

In this sense, the likes of RFT and VBDT (and other similar research traditions inside behavior analysis), are not simply aiming to provide an account of human language and thought, per se, but a behavior-analytic (i.e., evolutionary, naturalistic, and monistic) account of human psychology in whole cloth. Perhaps this is not that surprising when viewed in the context of Skinner’s (1953) volume, Science and Human Behavior, which by definition was an attempt to explain human behavior in purely scientific terms (e.g., without reference to mentalistic concepts). Of course, Skinner’s text relied very heavily on the terms and concepts that had been wrought from research conducted largely with non-humans, but the agenda was clearly concerned with explaining human psychology. Almost 70 years later behavior analysis has made considerable progress in studying human behavior in its own right, and a case could now be made that while the principles wrought from non-human research are not irrelevant or without value, the units of analysis for a uniquely symbolic (human) species require a unique behavior analytic account. In this sense, RFT, for example, is not simply an account of relational learning or reasoning, in the same way that VBDT is not simply an account of (human) naming. The scientific ambition is far greater than that — they are efforts to rise to the enormous challenge that Skinner lay before us in his 1953 treatise. When viewed in this light, the call and need for cooperation and collaboration inside behavior analysis, in studying the behavior of our uniquely symbolic species, seems particularly important.

In emphasizing the uniquely symbolic nature of human behavior, we are not seeking to create additional silos within behavior analysis (i.e., researchers focused on human language and thought versus those who are not). Indeed, it is important to note that there appear to be progressive and exciting developments emerging across the entire field. And some of these developments involve reviewing or re-working some of our most fundamental concepts, including reinforcement itself. For example, Baum (e.g., 2018) has argued that reinforcement does not strengthen operant behavior per se, but selects and directs it, and Cowie (e.g., 2018) has argued that a history of reinforcement exerts both prospective and retrospective control over behavior. In yet another long-standing and well established research area in behavior analysis, that of choice behavior, McDowell and colleagues (e.g., 2019) have achieved remarkable progress through the use of evolutionary dynamics simulations, with many quantitative relations emerging readily from the model. Overall, therefore, there appears to be a genuinely progressive ethos emerging within the entire field of behavior analysis, which has also been reflected in recent developments with the study of human language and thought. In RFT, for example, a new non-linear and dynamical response unit has been proposed, which fundamentally changes how (verbal) humans interact with reinforcement contingencies. And in a broad sense this view overlaps with the VBDT emphasis on the critical importance of naming (and in particular “incidental naming”) in changing how verbal contingencies feed into the verbal development of young children. 

When viewed in this light, the insulting characterization of behavior analysis as some sort of “intellectual ghetto” seems rather dated. Certainly, we believe that any temptation to “jump ship” and climb on board mainstream psychology, a vessel that could be seen as badly damaged below the water line by replication and measurement crises, should be resisted or at least seriously questioned. Of course, behavior analysis should always remain open to self-reflection and self-criticism, but it should not allow itself to be the subject of an overly negative cartoon caricature as a stagnating intellectual ghetto. Recent developments across the board just do not accord with this view.


In any case, we hope that you will enjoy reading the blog series and that it will draw us all out of our respective silos to help facilitate a stronger and more coherent tradition in the study of symbolic language and thought, and psychology more generally, within the science and practice of behavior analysis.



Barnes-Holmes, D., Barnes-Holmes, Y., Luciano, C., & McEnteggart, C. (2017). From IRAP and REC model to a multi-dimensional multi-level framework for analysing the dynamics of arbitrarily applicable relational responding. Journal of Contextual Behavioural Science, 6(4), 473-483.

Baum, W. M. (2018). Three laws of behavior: Allocation, induction, and covariance. Behavior Analysis: Research and Practice, 18, 239-251.

Cowie, S. (2018). Behavioral time travel: Control by past, present, and potential events. Behavior Analysis: Research and Practice, 18(2), 174-183.

Deacon, T.W. (1998). The symbolic species: The co-evolution of language and the brain. Norton.

Greer, R.D. & Speckman, J. (2009). The integration of speaker and listener responses: A theory of verbal development. The Psychological Record, 59(3), 449-488.

Harte, C. & Barnes-Holmes, D. (In press). A primer on Relational Frame Theory (RFT). In M.P. Twohig, M.E. Levin, & J.M. Peterson (Eds.), The Oxford Handbook of Acceptance and Commitment Therapy. Oxford University Press.

Hayes, S.C., Hofmann, S.G., & Wilson, D.S. (2020). Clinical psychology is an applied evolutionary science. Clinical Psychology Review, 81(2), 101892.

McDowell, J. J (2019). On the current status of the evolutionary theory of behavior dynamics. Journal of the Experimental Analysis of Behavior, 111, 162-182.

Sidman, M. (1994). Equivalence relations and behaviour: A research story. Boston, MA: Authors Cooperative.

Skinner, B.F. (1953). Science and human behaviour. Macmillan.

Sloan-Wilson, D., Hayes, S.C., Biglan, A., & Embry, D.D. (2014). Evolving the future: Toward a science of intentional change. Behavior and Brain Science, 37(4), 395-416. 


About the authors:

Prof. Dermot Barnes-Holmes received his D.Phil. in behavioral analysis and behavioral biology from the University of Ulster, Coleraine, N. Ireland. He returned to Ulster University in 2020 to take up a professorial position in the School of Psychology. Previously, he served as Senior Full Professor and Odysseus Laureate at Ghent University, Belgium, having previously served on the faculties of the National University of Ireland, Maynooth, and University College Cork. Dr. Barnes-Holmes is an extraordinarily prolific researcher who has made extensive contributions to the behavior analytic literature, especially in the areas of language and cognition. The competitive and prestigious Odysseus Laureate awarded to Dr. Barnes-Holmes in 2015 is just the most recent recognition of the esteem in which his work is held among behavioral scientists internationally.

Dr. Colin Harte received his PhD under the supervision of Professors Dermot and Yvonne Barnes-Holmes at Ghent University in Belgium. His doctoral work was part of the Odysseus research project which focused on the conceptual development of relational frame theory (RFT) as a behaviour analytic account of human language and cognition. His work during this time focused on exploring the behavioural dynamics involved in rule-governed behaviour, and persistent rule-following specifically. Since then, Colin has continued to be heavily involved in the empirical and conceptual development of RFT more generally. To this end, he has published 20 peer reviewed journal articles, 3 book chapters in edited volumes and presented multiple papers and workshops at international behaviour science conferences. He is currently an associate faculty lecturer in psychology at the National College of Ireland (NCI) in Dublin and has recently been awarded a post-doctoral research fellowship by the São Paulo research foundation (FAPESP) with Professor Julio de Rose which he intends to take up once it’s safe to travel again.