The role of crosstalk in dual-task performance: evidence from manipulating response-code overlap

The present study examined the role of crosstalk in dual-task interference using a combination of a nonspeeded visual task and an auditory-manual reaction time (RT) task. The potential for dual-task crosstalk was introduced by presenting in the visual task objects (e.g., a cup with a handle), which "afford" associated responses that were either spatially compatible or incompatible with the response in the RT task. Crucially, the degree of crosstalk was varied by instructing participants either to attend to the left-right orientation of the objects, creating explicit cross-task response-code overlap ("strong crosstalk"), or to attend to object identity (no direct overlap; "weak crosstalk"). The data indicated a relative benefit for cross-task compatible trials, which was much greater with strong crosstalk than with weak crosstalk. Crucially, however, even on compatible trials dual-task performance was substantially worse with strong crosstalk than with weak crosstalk. This overall cost of crosstalk suggests interference of response codes even on compatible dual-task trials.