Complexity

McDowell’s Lab

Complexity and Behavior

Text Box: I think the next century will be the century of complexity. (Stephen Hawking, 2000) The science of complexity is a relatively young science that is rapidly becoming “the spoiled child” of the scientific community. Its object of study consists of complex systems. Generally speaking, complex systems are dynamic, adaptive systems, governed by simple, low-level rules (e.g. natural selection) that, in time, give rise to novel, high-level features or behaviors (e.g. retractable claws, impulsivity, political attitudes, divorce, etc). These features are called emergent and their main characteristic is that they are not readily reducible to the rules that produce them or to simpler components of the system. For this reason they appear to be stand-alone entities (especially if the time span is large), and behavioral and psychological sciences have traditionally studied them as such. Today we know a great deal about the behavior of organisms, human and non-human (Journal of Experimental Behavior Analysis, 1958 - present; Journal of Applied Behavior Analysis, 1968 - present). However, not much is known about behavioral repertoires, which encompass a multitude of diverse patterns, such as reading, going out with friends, playing videogames, being fair/selfish, etc. These patterns are highly interconnected and interdependent. Changes in one pattern tend to reverberate through the entire repertoire, producing unexpected consequences. For example, a change in what a person reads may change the system dramatically, not only in frequency of going out, but in entourage, places, believes, attitudes, etc. Or consider a breakup: it does not affect only the schedule for Saturday night, but how a person dresses, talks, behaves to coworkers (who's behavior is, in turn, altered), etc. Behavioral repertoires are constantly adapting to environmental demands. In the case of modern humans the environments of interests are often social environments - the behaviors of others. The processes responsible for adaptation maintain the system in constant motion, sometimes giving rise to novel behaviors (e.g. pick up playing the violin) or to novel ways of behaving (e.g. more "intense", "depressed", etc.). Also, behavioral repertoires are sometimes marked by atypical, large scale events (e.g. marriage, divorce, promotion, etc.), events that may dramatically impact the entire system. However, behavioral repertoires are fairly robust; complete, irreversible shifts are quite rare. Usually the system recovers even after very serious alterations, such us the death of a loved one, relocation on a different continent, or getting the "dream job" (please note that "alterations" are not necessarily negative). These features seem to indicate that behavioral repertoires are indeed complex systems. This means that most (if not all) behavioral and psychological objects (e.g. AD/HD, smoking, delinquency, the Matching law, etc.) are not stand alone entities, but emergent properties of the system (thus produced by the rules that govern the system, under specific environmental demands, departing from specific initial conditions). In order to understand how they emerge, one must first identify the rules that govern the system. One possibility is that behavioral repertoires are governed by the low-level Darwinian processes of Selection, Recombination, and Mutation, which affect behavioral patterns much like they affect species: behaviors that are more successful (in acquiring resources or avoiding threats) tend to be maintained in the repertoires; those that are not, perish. This idea was implemented in the Computational Theory (McDowell, 2004) and it has been the focus of our research for the past decade or so.

Emory University, Department of Psychology, Atlanta, GA, USA

The Evolutionary Theory

Future Directions

Research Overview

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