Sensory-motor modality compatibility in multitasking: The influence of processing codes.

Sensory-motor modality compatibility is defined as the similarity between the sensory modality and the modality of response-related effects. Previous dual-task and task-switching studies have shown higher performance costs for coordinating relatively incompatible sensory-motor modality mappings (i.e., auditory-manual and visual-vocal) compared to more compatible mappings (i.e., auditory-vocal and visual-manual). Until now, however, little attention has been paid to potential variability in effects of modality compatibility depending on different processing codes. In the present study, we independently varied the processing codes of input and output (nonverbal-spatial, nonverbal-nominal, verbal-spatial, verbal-nominal) while participants switched between incompatible and compatible sensory-motor modality mappings. Beside higher switch costs for switching between incompatible sensory-motor modality mappings than for switching between compatible mappings, the results revealed stronger effects of modality compatibility on switch costs for verbal input than for nonverbal input codes. This suggests that priming mechanisms between sensory input and compatible motor output are modulated by the processing code of the sensory input. As possible explanations, we assume a higher degree of concordance with output processing codes as well as stronger associations with potential response effects for verbal than for nonverbal input.