Goethe, K. 1 & Oberauer, K. 2
1 Department of Psychology, University of Potsdam, Potsdam, Germany
2 Department of Psychology, University of Zurich, Zurich, Switzerland
In two experiments we examined whether dual-task costs were influenced by the content specific characteristics of two tasks. Four groups practiced two tasks which differed across groups with respect to their modality pairings. Modality pairings increased or decreased representational overlap across tasks. The results clearly showed that the effects of representational overlap on dual-task costs were higher than one would predict according to their effects on single-task performance. Moreover, for two groups with low representational overlap dual-task costs vanished after practice. This strongly supports the view that a qualitative switch in processing from serial to parallel was realized for these task combinations. The observed effects cannot be explained by dual-task theories assuming response selection to be amodal or sequential for two tasks. We postulate that the manipulation of representational overlap has influenced the amount of crosstalk between the tasks at the stage of response selection with low crosstalk promoting parallel processing after practice.