An Investigation of the Relationships Between Autistic Traits and Crossmodal Correspondences in Typically Developing Adults

Autism spectrum disorder (ASD) includes characteristics such as social and behavioral deficits that are considered common across the general population rather than unique to people with the diagnosis. People with ASD are reported to have sensory irregularities, including crossmodal perception. Crossmodal correspondences are phenomena in which arbitrary crossmodal inputs affect behavioral performance. Crossmodal correspondences are considered to be established through associative learning, but the learning cues are considered to differ across the types of correspondences. In order to investigate whether and how ASD traits affect crossmodal associative learning, this study examined the relationships between the magnitude of crossmodal correspondences and the degree of ASD traits among non-diagnosed adults. We found that, among three types of crossmodal correspondences (brightness–loudness, visual size–pitch, and visual location–pitch pairs), the brightness–loudness pair was related with total ASD traits and a subtrait (social skill). The magnitude of newly learned crossmodal associations (the visual apparent motion direction–pitch pair) also showed a relationship with an ASD subtrait (attention switching). These findings demonstrate that there are unique relationships between crossmodal associations and ASD traits, indicating that each ASD trait is differently involved in sensory associative learning.

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.

Mutual Influences of Intermodal Visual/Tactile Apparent Motion and Auditory Motion with Uncrossed and Crossed Arms

Intra-modal apparent motion has been shown to be affected or ‘captured’ by information from another, task-irrelevant modality, as shown in cross-modal dynamic capture effect. Here we created inter-modal apparent motion between visual and tactile stimuli and investigated whether there are mutual influences between auditory apparent motion and inter-modal visual/tactile apparent motion. Moreover, we examined whether and how the spatial remapping between somatotopic and external reference frames of tactile events affect the cross-modal capture between auditory apparent motion and inter-modal visual/tactile apparent motion, by introducing two arm postures: arms-uncrossed and arms-crossed. In Experiment 1, we used auditory stimuli (auditory apparent motion) as distractors and inter-modal visual/tactile stimuli (inter-modal apparent motion) as targets while in Experiment 2 we reversed the distractors and targets. In Experiment 1, we found a general detrimental influence of arms-crossed posture in the task of discrimination of direction in visual/tactile stream, but in Experiment 2, the influence of arms-uncrossed posture played a significant role in modulating the inter-modal visual/tactile stimuli capturing over auditory apparent motion. In both Experiments, the synchronously presented motion streams led to noticeable directional congruency effect in judging the target motion. Among the different modality combinations, tactile to tactile apparent motion (TT) and visual to visual apparent motion (VV) are two signatures revealing the asymmetric congruency effects. When the auditory stimuli were targets, the congruency effect was largest with VV distractors, lowest with TT distractors; the pattern was reversed when the auditory stimuli were distractors. In addition, across both experiments the congruency effect in visual to tactile (VT) and tactile to visual (TV) apparent motion was intermediate between the effect-sizes in VV and TT. We replicated the above findings with a block-wise design (Experiment 3). In Experiment 4, we introduced static distractor events (visual or tactile stimulus), and found the modulation of spatial remapping of distractors upon AA motion is reduced. These findings suggest that there are mutual but a robust asymmetric influence between intra-modal auditory apparent motion and intermodal visual/tactile apparent motion. We proposed that relative reliabilities in directional information between distractor and target streams, summed over a remapping process between two spatial reference frames, determined this asymmetric influence.