Activation of a Motor Plan: The A-not-B Error

Flexibility Linda B. Smith Human intelligence reveals both remarkable stability and nimble flexibility. Stability emerges from the incorporation of the past into the present. Flexibility, in turn, requires an abandoment of (or selection among) past ways, a shifting of responses to meet new circumstances. All of cognitive science, one way or another, is concerned with processes of stability and/or flexbility (see Samuelson & Smith, 2000). These are also the core issues in this volume, a volume onstensibly about connectionist versus dynamic systems approaches to cognitive development. My charge in writing this chapter was to consider infant perseveration in the A-not-B task from a dynamic systems point of view. And so I shall. But my main point is not an argument for dynamic systems over connectionism, as that seems not to be an argument much worth having (see Samuelson & Smith, 2000). Much more interesting are the phenomena themselves. Furthermore, both connectionist and dynamic systems accounts of the A-not-B error provide insight into the multilayered and nested dynamics that make up human intelligence. And our intelligence, for the sake of coherence, always leans a bit to the just-previous past and is thus susceptible to preseveration—stable patterns or stability. This is a main point of this chapter. A second point is that human intelligence is also always open to sensory input and is thus always being perturbed. These perturbations can yield either variability or new stable patterns. It is the latter result that yields flexibility. The dynamic systems approach to the A-not-B error has provided new insights into the phenomenon itself, into the larger issues of stability and flexibility, and into the multilayered dynamics of the sensorimotor processes that underlie all of these.