Adapting the Crossmodal Congruency Task for Measuring the Limits of Visual- Tactile Interactions Within and Between Groups

The crossmodal congruency task (CCT) is a commonly used paradigm for measuring visual–tactile interactions and how these may be influenced by discrepancies in space and time between the tactile target and visual distractors. The majority of studies which have used this paradigm have neither measured , nor attempted to control, individual variability in unisensory (tactile) performance. We have developed a version of the CCT in which unisensory baseline performance is constrained to enable comparisons within and between participant groups. Participants were instructed to discriminate between single and double tactile pulses presented to their dominant hand, at their own approximate threshold level. In Experiment 1, visual distractors were presented at −30 ms, 100 ms, 200 ms and 400 ms stimulus onset asynchronies. In Experiment 2, ipsilateral visual distractors were presented 0 cm, 21 cm, and 42 cm vertically from the target hand, and 42 cm in a symmetrical, contralateral position. Distractors presented −30 ms and 0 cm from the target produced a significantly larger congruency effect than at other time points and spatial locations. Thus, the typical limits of visual– tactile interactions were replicated using a version of the task in which baseline performance can be constrained. The usefulness of this approach is supported by the observation that tactile thresholds correlated with self-reported autistic traits in this non-clinical sample. We discuss the suitability of this adapted version of the CCT for measuring visual–tactile interactions in populations where unisensory tactile ability may differ within and between groups.