Multisensory Research最新文献

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.

Motion discrimination is essential for animals to avoid collisions, to escape from predators, to catch prey or to communicate. Although most terrestrial vertebrates can benefit by combining concurrent stimuli from sound and vision to obtain a most salient percept of the moving object, there is little research on the mechanisms involved in such cross-modal motion discrimination. We used European starlings as a model with a well-studied visual and auditory system. In a behavioural motion discrimination task with visual and acoustic stimuli, we investigated the effects of cross-modal interference and attentional processes. Our results showed an impairment of motion discrimination when the visual and acoustic stimuli moved in opposite directions as compared to congruent motion direction. By presenting an acoustic stimulus of very short duration, thus lacking directional motion information, an additional alerting effect of the acoustic stimulus became evident. Finally, we show that a temporally leading acoustic stimulus did not improve the response behaviour compared to the synchronous presentation of the stimuli as would have been expected in case of major alerting effects. This further supports the importance of congruency and synchronicity in the current test paradigm with a minor role of attentional processes elicited by the acoustic stimulus. Together, our data clearly show cross-modal interference effects in an audio-visual motion discrimination paradigm when carefully selecting real-life stimuli under parameter conditions that meet the known criteria for cross-modal binding.

The ability to efficiently combine information from different senses is an important perceptual process that underpins much of our daily activities. This process, known as multisensory integration, varies from individual to individual, and is affected by the ageing process, with impaired processing associated with age-related conditions, including balance difficulties, mild cognitive impairment and cognitive decline. Impaired multisensory perception has also been associated with a range of neurodevelopmental conditions, where novel intervention approaches are actively sought, for example dyslexia and autism. However, it remains unclear to what extent and how multisensory perception can be modified by training. This systematic review aims to evaluate the evidence that we can train multisensory perception in neurotypical adults. In all, 1521 studies were identified following a systematic search of the databases PubMed, Scopus, PsychInfo and Web of Science. Following screening for inclusion and exclusion criteria, 27 studies were chosen for inclusion. Study quality was assessed using the Methodological Index for Non-Randomised Studies (MINORS) tool and the Cochrane Risk of Bias tool 2.0 for Randomised Control Trials. We found considerable evidence that in-task feedback training using psychophysics protocols led to improved task performance. The generalisability of this training to other tasks of multisensory integration was inconclusive, with few studies and mixed findings reported. Promising findings from exercise-based training indicate physical activity protocols warrant further investigation as potential training avenues for improving multisensory integration. Future research directions should include trialling training protocols with clinical populations and other groups who would benefit from targeted training to improve inefficient multisensory integration.

A number of perplexing phenomena in the area of olfactory/flavour perception may fruitfully be explained by the suggestion that chemosensory mental imagery can be triggered automatically by perceptual inputs. In particular, the disconnect between the seemingly limited ability of participants in chemosensory psychophysics studies to distinguish more than two or three odorants in mixtures and the rich and detailed flavour descriptions that are sometimes reported by wine experts; the absence of awareness of chemosensory loss in many elderly individuals; and the insensitivity of the odour-induced taste enhancement (OITE) effect to the mode of presentation of olfactory stimuli (i.e., orthonasal or retronasal). The suggestion made here is that the theory of predictive coding, developed first in the visual modality, be extended to chemosensation. This may provide a fruitful way of thinking about the interaction between mental imagery and perception in the experience of aromas and flavours. Accepting such a suggestion also raises some important questions concerning the ecological validity/meaning of much of the chemosensory psychophysics literature that has been published to date.

Autistic children show reduced multisensory integration of audiovisual speech stimuli in response to the McGurk illusion. Previously, it has been shown that adults can integrate sung McGurk tokens. These sung speech tokens offer more salient visual and auditory cues, in comparison to the spoken tokens, which may increase the identification and integration of visual speech cues in autistic children. Forty participants (20 autism, 20 non-autistic peers) aged 7-14 completed the study. Participants were presented with speech tokens in four modalities: auditory-only, visual-only, congruent audiovisual, and incongruent audiovisual (i.e., McGurk; auditory 'ba' and visual 'ga'). Tokens were also presented in two formats: spoken and sung. Participants indicated what they perceived via a four-button response box (i.e., 'ba', 'ga', 'da', or 'tha'). Accuracies and perception of the McGurk illusion were calculated for each modality and format. Analysis of visual-only identification indicated a significant main effect of format, whereby participants were more accurate in sung versus spoken trials, but no significant main effect of group or interaction effect. Analysis of the McGurk trials indicated no significant main effect of format or group and no significant interaction effect. Sung speech tokens improved identification of visual speech cues, but did not boost the integration of visual cues with heard speech across groups. Additional work is needed to determine what properties of spoken speech contributed to the observed improvement in visual accuracy and to evaluate whether more prolonged exposure to sung speech may yield effects on multisensory integration.

Visually perceived roughness of 3D textures varies with illumination direction. Surfaces appear rougher when the illumination angle is lowered resulting in a lack of roughness constancy. Here we aimed to investigate whether the visual system also relies on illumination-dependent features when judging roughness in a crossmodal matching task or whether it can access illumination-invariant surface features that can also be evaluated by the tactile system. Participants ( N = 32) explored an abrasive paper of medium physical roughness either tactually, or visually under two different illumination conditions (top vs oblique angle). Subsequently, they had to judge if a comparison stimulus (varying in physical roughness) matched the previously explored standard. Matching was either performed using the same modality as during exploration (intramodal) or using a different modality (crossmodal). In the intramodal conditions, participants performed equally well independent of the modality or illumination employed. In the crossmodal conditions, participants selected rougher tactile matches after exploring the standard visually under oblique illumination than under top illumination. Conversely, after tactile exploration, they selected smoother visual matches under oblique than under top illumination. These findings confirm that visual roughness perception depends on illumination direction and show, for the first time, that this failure of roughness constancy also transfers to judgements made crossmodally.