Contextual consistency promotes visual-haptic simultaneity perception

In this study, we investigate the influence of causality validity in the information provided to each of two sensory modalities on the integration of multisensory information. For the purpose, stimuli that simulated a causal event, a ball striking an object, were created using a head-mounted display and a haptic device. The visual position and motion of the object were aligned to the haptic feedback received by the observer. The haptic device delivered a vibration around the moment of impact. Three vibration directions were used to assess the effect of the validity of the causal relationship between the two events. Participants were asked to determine whether the collision of the ball and the vibration were simultaneous. The findings revealed that the participants were more likely to perceive the events as simultaneous when the direction of the vibration matched the ball's movement. These results suggest that valid causal consistency across different modalities enhances the binding of these signals as originating from a single source.

The influence of spatial frequency information on temporal synchrony perception on audiovisual stimuli

Previous studies have shown that the spatial frequency (SF) of visual stimuli alters the perceived timing of subjective simultaneity. However, these studies have been limited to the effects of a single SF component. In this study, I measured and compared the points of subjective simultaneity (PSS) for audiovisual stimuli among low, high, and composited SF components. This experiment comprised a dual-presentation timing task and a ternary response format to eliminate response bias. The results indicated that the PSS value of the composition-SF stimuli was more toward visual-lead timing than the low-SF stimuli and did not differ significantly from that of the high-SF stimuli. The correlation coefficients showed that the PSS in composition-SF stimuli marginally approximated that of high-SF stimuli higher than that of low-SF stimuli. Future studies are needed to confirm these findings using visual stimuli with a wider range of SF components and with a modulated contrast.

Temporal order judgment of multisensory stimuli in rat and human

We do not fully understand the resolution at which temporal information is processed by different species. Here we employed a temporal order judgment (TOJ) task in rats and humans to test the temporal precision with which these species can detect the order of presentation of simple stimuli across two modalities of vision and audition. Both species reported the order of audiovisual stimuli when they were presented from a central location at a range of stimulus onset asynchronies (SOA)s. While both species could reliably distinguish the temporal order of stimuli based on their sensory content (i.e., the modality label), rats outperformed humans at short SOAs (less than 100 ms) whereas humans outperformed rats at long SOAs (greater than 100 ms). Moreover, rats produced faster responses compared to humans. The reaction time data further revealed key differences in decision process across the two species: at longer SOAs, reaction times increased in rats but decreased in humans. Finally, drift-diffusion modeling allowed us to isolate the contribution of various parameters including evidence accumulation rates, lapse and bias to the sensory decision. Consistent with the psychophysical findings, the model revealed higher temporal sensitivity and a higher lapse rate in rats compared to humans. These findings suggest that these species applied different strategies for making perceptual decisions in the context of a multimodal TOJ task.