Impact of input modality on task-switching cost: A behavioural investigation of domain general versus modality-specific account of cognitive flexibility

Cognitive flexibility is one of the main executive functions, traditionally considered as part of domain-general, modality-independent, processes. Nevertheless, evidence from behavioural and brain-imaging studies suggests that this central ability remains sensitive to the modality of sensory input. Here, we further investigated the impact of information modality by addressing two related questions. First, we examined whether this sensitivity to input modality could be driven by the input modality itself, in the absence of the manipulation of modality-(in)compatibility between different elements in a protocol as conducted in most previous studies. Second, we examined whether cognitive flexibility operating on auditory and visual input is controlled by a unitary, modality-independent, domain-general mechanism as traditionally claimed or there is also a modality-specific component. To these aims, we conducted a task-switching paradigm on a large sample of 120 participants. Two alternated semantic judgment tasks were performed on spoken or written language inputs, which were presented in two separate blocks. At the group level, the analyses showed significantly higher switching costs in the visual modality, a pattern that is also found in most participants. Interestingly, although there were moderate positive correlations between switching costs observed in the two modalities, only the cost in the visual modality was predicted by global performance. Overall, the findings from the different analyses suggest that cognitive flexibility may rely on both central and peripheral processes, which are differently constrained by the characteristics of the sensory input.