Investigating task and modality switching costs using bimodal stimuli

Investigations of concurrent task and modality switching effects have to date been studied under conditions of uni-modal stimulus presentation. As such, it is difficult to directly compare resultant task and modality switching effects, as the stimuli afford both tasks on each trial, but only one modality. The current study investigated task and modality switching using bi-modal stimulus presentation under various cue conditions: task and modality (double cue), either task or modality (single cue) or no cue. Participants responded to either the identity or the position of an audio–visual stimulus. Switching effects were defined as staying within a modality/task (repetition) or switching into a modality/task (change) from trial n − 1 to trial n, with analysis performed on trial n data. While task and modality switching costs were sub-additive across all conditions replicating previous data, modality switching effects were dependent on the modality being attended, and task switching effects were dependent on the task being performed. Specifically, visual responding and position responding revealed significant costs associated with modality and task switching, while auditory responding and identity responding revealed significant gains associated with modality and task switching. The effects interacted further, revealing that costs and gains associated with task and modality switching varying with the specific combination of modality and task type. The current study reconciles previous data by suggesting that efficiently processed modality/task information benefits from repetition while less efficiently processed information benefits from change due to less interference of preferred processing across consecutive trials.