Multisensory Research最新文献

The mechanisms underlying geocentric (orientations of an object or the body relative to 'gravity') and egocentric estimates (object orientation relative to the 'body') have each been examined; however, little is known regarding the association between these estimates, especially when the body is nearly upright. To address this, we conducted two psychophysical experiments. In Experiment 1, participants estimated the direction of a visual line (subjective visual vertical; SVV) and their own body relative to gravity (subjective body tilt; SBT) and the direction of a visual line relative to the body longitudinal axis (subjective visual body axis; SVBA) during a small-range whole-body roll tilt. We evaluated the correlations between performance on each of these tasks as covariates of actual body tilt angles. Our results showed a significant correlation of performance (estimation errors) on the SVBA task with performance on the SBT task but not performance on the SVV task at the group level after adjusting for the actual body tilt angles, suggesting a link between the estimates for SVBA and SBT tasks. To confirm this relationship, in Experiment 2, we further assessed whether manipulating the subjective direction of the body axis by providing visual feedback in the SVBA task subsequently affected SBT performance. We found that feedback in the SVBA task significantly shifted the SBT angles even when the actual body angles were identical. The observed association between SVBA and SBT performance supports at least a partially shared mechanism underlying body tilt and egocentric estimates when the body is nearly upright.

A growing body of experimental research now demonstrates that neurologically normal individuals associate different taste qualities with design features such as curvature, symmetry, orientation, texture and movement. The form of everything from the food itself through to the curvature of the plateware on which it happens to be served, and from glassware to typeface, not to mention the shapes of/on food product packaging have all been shown to influence people's taste expectations, and, on occasion, also their taste/food experiences. Although the origins of shape-taste and other form-taste crossmodal correspondences have yet to be fully worked out, it would appear that shape qualities are occasionally elicited directly. However, more often, there may be a metaphorical attempt to translate the temporal qualities of taste sensations into a spatial analogue. At the same time, emotional mediation may sometimes also play a role in the affinity people experience between shape properties and taste. And finally, it should be acknowledged that associative learning of the relation between packaging shapes, glassware shapes, logos, labels and iconic food forms that commonly co-occur with specific taste properties (i.e., in the case of branded food products) may also play an important role in determining the nature of shape-taste correspondences. Ultimately, however, any attempt to use such shape-taste correspondences to nudge people's behaviour/perception in the real world is made challenging due to the fact that shape properties are associated with multiple qualities, and not just taste.

The integration of vestibular, visual and body cues is a fundamental process in the perception of self-motion and is commonly experienced in an upright posture. However, when the body is tilted in an off-vertical orientation these signals are no longer aligned relative to the influence of gravity. In this study, the perceived timing of visual motion was examined in the presence of sensory conflict introduced by manipulating the orientation of the body, generating a mismatch between body and vestibular cues due to gravity and creating an ambiguous vestibular signal of either head tilt or translation. In a series of temporal-order judgment tasks, participants reported the perceived onset of a visual scene simulating rotation around the yaw axis presented in virtual reality with a paired auditory tone while in an upright, supine and side-recumbent body position. The results revealed that the perceived onset of visual motion was further delayed from zero (i.e., true simultaneity between visual onset and a reference auditory tone) by approximately an additional 30 ms when viewed in a supine or side-recumbent orientation compared to an upright posture. There were also no significant differences in the timing estimates of the visual motion between all the non-upright orientations. This indicates that the perceived timing of visual motion is negatively impacted by the presence of conflict in the vestibular and body signals due to the direction of gravity and body orientation, even when the mismatch is not in the direct plane of the axis of rotation.

In multisensory environments, our brains perform causal inference to estimate which sources produce specific sensory signals. Decades of research have revealed the dynamics which underlie this process of causal inference for multisensory (audiovisual) signals, including how temporal, spatial, and semantic relationships between stimuli influence the brain's decision about whether to integrate or segregate. However, presently, very little is known about the relationship between metacognition and multisensory integration, and the characteristics of perceptual confidence for audiovisual signals. In this investigation, we ask two questions about the relationship between metacognition and multisensory causal inference: are observers' confidence ratings for judgments about Congruent, McGurk, and Rarely Integrated speech similar, or different? And do confidence judgments distinguish between these three scenarios when the perceived syllable is identical? To answer these questions, 92 online participants completed experiments where on each trial, participants reported which syllable they perceived, and rated confidence in their judgment. Results from Experiment 1 showed that confidence ratings were quite similar across Congruent speech, McGurk speech, and Rarely Integrated speech. In Experiment 2, when the perceived syllable for congruent and McGurk videos was matched, confidence scores were higher for congruent stimuli compared to McGurk stimuli. In Experiment 3, when the perceived syllable was matched between McGurk and Rarely Integrated stimuli, confidence judgments were similar between the two conditions. Together, these results provide evidence of the capacities and limitations of metacognition's ability to distinguish between different sources of multisensory information.

A single bout of aerobic exercise is related to positive changes in higher-order cognitive function among older adults; however, the impact of aerobic exercise on multisensory processing remains unclear. Here we assessed the effects of a single bout of aerobic exercise on commonly utilized tasks that measure audiovisual multisensory processing: response time (RT), simultaneity judgements (SJ), and temporal-order judgements (TOJ), in a pilot study. To our knowledge this is the first effort to investigate the effects of three well-controlled intervention conditions on multisensory processing: resting, completing a cognitively demanding task, and performing aerobic exercise for 20 minutes. Our results indicate that the window of time within which stimuli from different modalities are integrated and perceived as simultaneous (temporal binding window; TBW) is malleable and changes after each intervention condition for both the SJ and TOJ tasks. Specifically, the TBW consistently became narrower post exercise while consistently increasing in width post rest, suggesting that aerobic exercise may improve temporal perception precision via broad neural change rather than targeting the specific networks that subserve either the SJ or TOJ tasks individually. The results from the RT task further support our findings of malleability of the multisensory processing system, as changes in performance, as assessed through cumulative probability models, were observed after each intervention condition. An increase in integration (i.e., greater magnitude of multisensory effect) however, was only found after a single bout of aerobic exercise. Overall, our results indicate that exercise uniquely affects the central nervous system and may broadly affect multisensory processing.

Autistic youth demonstrate differences in processing multisensory information, particularly in temporal processing of multisensory speech. Extensive research has identified several key brain regions for multisensory speech processing in non-autistic adults, including the superior temporal sulcus (STS) and insula, but it is unclear to what extent these regions are involved in temporal processing of multisensory speech in autistic youth. As a first step in exploring the neural substrates of multisensory temporal processing in this clinical population, we employed functional magnetic resonance imaging (fMRI) with a simultaneity-judgment audiovisual speech task. Eighteen autistic youth and a comparison group of 20 non-autistic youth matched on chronological age, biological sex, and gender participated. Results extend prior findings from studies of non-autistic adults, with non-autistic youth demonstrating responses in several similar regions as previously implicated in adult temporal processing of multisensory speech. Autistic youth demonstrated responses in fewer of the multisensory regions identified in adult studies; responses were limited to visual and motor cortices. Group responses in the middle temporal gyrus significantly interacted with age; younger autistic individuals showed reduced MTG responses whereas older individuals showed comparable MTG responses relative to non-autistic controls. Across groups, responses in the precuneus covaried with task accuracy, and anterior temporal and insula responses covaried with nonverbal IQ. These preliminary findings suggest possible differences in neural mechanisms of audiovisual processing in autistic youth while highlighting the need to consider participant characteristics in future, larger-scale studies exploring the neural basis of multisensory function in autism.