Multiple spatial correspondence effects on dual-task performance

Three dual-task experiments were conducted to examine whether the underaddi tive interaction of the Simon effect and stimulus onset asynchrony (SOA) on Task 2 performance is due to decay. The experiments tested whether the rev erse Simon effect obtained with an incompatible stimulus-response (S-R) map ping would show an overadditive interaction with SOA, as predicted by R. De Jong, C.-C. Liang, and E. Lauber's (1994) dual-process model. Tone or lett er identification tasks with vocal or keypress responses were used as Task 1. Task 2 was keypresses to arrow direction (or letter identity in Experime nt i). For all experiments, the normal Simon effect showed an underadditive interaction with SOA, but the reverse Simon effect did not show an overadd itive interaction. The results imply that the dual-process model is not app licable to the dual-task context. Multiple correspondence effects across ta sks implicate an explanation in terms of automatic S-R translation.