A DYNAMIC-MODEL OF REACTION-TIME IN A SHORT-TERM-MEMORY TASK

In this article we hypothesized that the trial to trial variability in speed of access to recently presented information is deterministic in nature and that it reflects important properties of immediate memory. Application of analytic techniques emerging from the science of nonli near dynamical systems to data obtained from the Sternberg (1966, 1970 ) short-term memory task corroborates the view. A simple nonlinear dif ference equation, consistent with fuzzy-trace theory (Brainerd & Reyna , 1999), was then proposed to describe the dynamics underlying reactio n time (RT) on the Sternberg task. The model posits that RT is a funct ion of the interaction of two control parameters: susceptibility to in terference (SI) and episodic activation (EA). Evaluation of the model indicated an exceptionally good fit with the raw empirical observation s. Age comparisons of the model parameters revealed that adults exhibi ted higher levels of SI and EA. Although the finding that adults exhib ited higher levels of SI than children runs counter to theory and othe r empirical results, further analysis revealed that adults exhibited l ower levels of SI relative to EA than children. Thus, children may exh ibit slower disintegration of verbatim memory traces than adults due t o interference; however, adults may be more efficient at redintegratin g verbatim memory traces than children. (C) 1994 Academic Press, Inc.