Modality compatibility (MC) describes the match between the stimulus modality and the modality of the anticipated response effect (e.g., vocal responses usually lead to auditory effects). Several task switching studies demonstrated larger switch costs when switching between two modality-incompatible mappings (auditory-manual and visual-vocal) compared to switching between two modality-compatible mappings (auditory-vocal and visual-manual).
Interestingly, previous research on MC in dual tasks suggests that MC affects older adults more strongly than young adults. The aim of our current study was to determine whether this age-related effect transfers to task switching and moreover, whether specifically older adults benefit from longer preparation in this situation. In our experiment, we compared performance of younger and older adults in modality compatible and incompatible conditions, while varying preparation time. Stimuli were bimodal (auditory and visual), while unimodal cues indicated the relevant target modality. Participants had to identify the location of the target modality (left vs. right) in the previously assigned response modality (vocal or manual). As expected, we found a larger MC effect in task switching for older compared to young adults. Regarding preparation time, young adults tended to show more efficient task preparation, while the effect of MC was not affected by preparation time. Together, our findings indicate that older adults suffer more than young adults of the between-task backwards crosstalk that arises when switching between incompatible modality mapping; and that the the effect of MC remains independent of preparation processes.