Task Switching: A PDP Model

• Published in: Cognitive psychology Vol. 44; no. 3; pp. 297 - 337
• Main Authors: Gilbert, Sam J., Shallice, Tim
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.05.2002; Elsevier; Academic Press
• Subjects: Associative Learning; Biological and medical sciences; Cognition & reasoning; Cognition. Intelligence; executive functions; Fundamental and applied biological sciences. Psychology; Humans; Key Words: task switching; Mental Processes; Miscellaneous; Models, Psychological; parallel distributed processing; Psychology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reaction Time; Stimuli; Stroop effect; task set; Theory; task set; parallel distributed processing; Key Words: task switching; Stroop effect; executive functions; Human; Executive function; Response selection; Task switching; Cognition; Simulation model; Neural network; Connectionism; Cognitive control
• ISSN: 0010-0285; 1095-5623
• DOI: 10.1006/cogp.2001.0770

When subjects switch between a pair of stimulus–response tasks, reaction time is slower on trial N if a different task was performed on trial N − 1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on “switch trials” can be slowed by an extended response selection process which results from (a) persisting, inappropriate states of activation and inhibition of task-controlling representations; and (b) associative learning, which allows stimuli to evoke tasks sets with which they have recently been associated (as proposed by Allport & Wylie, 2000). The model provides a good fit to a large body of empirical data, including findings which have been seen as problematic for this explanation of switch costs, and shows similar behavior when the parameters are set to random values, supporting Allport and Wylie's proposal.