Seeing or not Seeing Where Your Hands Are. The Influence of Visual Feedback About Hand Position on the Interaction Between Nociceptive and Visual Stimuli

Examining the mechanisms underlying crossmodal interaction between nociceptive and visual stimuli is crucial to understand how humans handle potential bodily threats in their environment. It has recently been shown that nociceptive stimuli can affect the perception of visual stimuli, provided that they occur close together in external space. The present study addresses the question whether these crossmodal interactions between nociceptive and visual stimuli are mediated by the visually perceived proximity between the visual stimuli and the limb on which nociceptive stimuli are applied, by manipulating the presence vs. absence of visual feedback about the position of the stimulated limb. Participants performed temporal order judgments on pairs of visual stimuli, shortly preceded by nociceptive stimuli, either applied on one hand or both hands simultaneously. The hands were placed near the visual stimuli and could either be seen directly, seen through a glass barrier, or hidden from sight with a wooden board. Unilateral nociceptive stimuli induced spatial biases to the advantage of visual stimuli presented near the stimulated hand, which were greater in the conditions in which the hands were seen than in the condition in which vision was prevented. Spatial biases were not modulated by the presence of the glass barrier, minimizing the possibility that the differential effect between the vision and no-vision conditions is solely due to the presence of the barrier between the hands and the visual stimuli. These findings highlight the importance of visual feedback for determining spatial mapping between nociceptive and visual stimuli for crossmodal interaction.

Cognitive Styles Differentiate Crossmodal Correspondences Between Pitch Glide and Visual Apparent Motion

Crossmodal correspondences are the automatic associations that most people have between different basic sensory stimulus attributes, dimensions, or features. For instance, people often show a systematic tendency to associate moving objects with changing pitches. Cognitive styles are defined as an individual’s consistent approach to think, perceive, and remember information, and they reflect qualitative rather than quantitative differences between individuals in their thinking processes. Here we asked whether cognitive styles played a role in modulating the crossmodal interaction. We used the visual Ternus display in our study, since it elicits two distinct apparent motion percepts: element motion (with a shorter interval between the two Ternus frames) and group motion (with a longer interval between the two frames). We examined the audiovisual correspondences between the visual Ternus movement directions (upward or downward) and the changes of pitches of concurrent glides (ascending frequency or descending frequency). Moreover, we measured the cognitive styles (with the Embedded Figure Test) for each participant. The results showed that congruent correspondence between pitch-ascending (decreasing) glides and moving upward (downward) visual directions led to a more dominant percept of ‘element motion’, and such an effect was typically observed in the field-independent group. Importantly, field-independent participants demonstrated a high efficiency for identifying the properties of audiovisual events and applying the crossmodal correspondence in crossmodal interaction. The results suggest cognitive styles could differentiate crossmodal correspondences in crossmodal interaction.