[Attentional control and task-switching costs investigated by the group version of the Stroop tasks]

When individuals are required to frequently switch among a small set of simple tasks, immediately after switching tasks, the responses become substantially slower and usually more error-prone. This phenomenon is known as the "switching cost." Two main hypotheses have been proposed to explain switching cost: (1) Proactive interference and (2) Time for task-set reconfiguration. The present study examined the relationship between the attentional control load of switching tasks and the switching cost from the perspective of the time for task-set reconfiguration hypothesis, by using the group version of the Stroop tasks. Healthy participants (N = 216; mean age 19.9 years) participated in the study. Four switching conditions were used: (1) No-switch, (2) Selective input control switch, (3) S-R mapping switch, and (4) Translation process switch. The results indicated that there was no significant difference between the number of correct responses in conditions (1) and (3), whereas there was a significant reduction in the number of correct responses in condition (4) relative to (1) and (2). These findings suggest that the switch cost in Stroop and reverse Stroop tasks results from the time taken for attentional control, such as the selective input control switch and the translation process switch.