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The brain-time account posits that the physical timing of sensory-evoked neural activity determines the perceived timing of corresponding sensory events. A canonical model formalises this account for tasks such as simultaneity and order judgements: Signals arrive at a decision centre in an order, and at a temporal offset, shaped by neural propagation times. This model assumes that the noise affecting people's temporal judgements is primarily neural-latency noise, i.e. variation in propagation times across trials, but this assumption has received little scrutiny. Here, we recorded EEG alongside simultaneity judgements from 50 participants in response to combinations of visual, auditory and tactile stimuli. Bootstrapping of ERP components was used to estimate neural-latency noise, and simultaneity judgements were modelled to estimate the precision of timing judgements. We obtained the predicted correlation between neural and behavioural measures of latency noise, supporting a fundamental feature of the canonical model of perceived timing., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Humans might possess either a single (amodal) internal clock or multiple clocks for different sensory modalities. Sensitivity could be improved by the provision of multiple signals. Such improvements can be predicted quantitatively, assuming estimates are combined by summation, a process described as optimal when summation is weighted in accordance with the variance associated with each of the initially independent estimates. This possibility was assessed for visual and tactile information regarding temporal intervals. In Experiment 1, 12 musicians and 12 nonmusicians judged durations of 300 and 600 ms, compared to test values spanning these standards. Bimodal precision increased relative to unimodal conditions, but not to the extent predicted by optimally weighted summation. In Experiment 2, 6 musicians and 6 other participants each judged 6 standards, ranging from 100 ms to 600 ms, with conflicting cues providing a measure of the weight assigned to each sensory modality. A weighted integration model best fitted these data, with musicians more likely to select near-optimal weights than nonmusicians. Overall, data were consistent with the existence of separate visual and tactile clock components at either the counter/integrator or memory stages. Independent estimates are passed to a decisional process, but not always combined in a statistically optimal fashion. (PsycINFO Database Record, ((c) 2017 APA, all rights reserved).)

Observers change their audio-visual timing judgements after exposure to asynchronous audiovisual signals. The mechanism underlying this temporal recalibration is currently debated. Three broad explanations have been suggested. According to the first, the time it takes for sensory signals to propagate through the brain has changed. The second explanation suggests that decisional criteria used to interpret signal timing have changed, but not time perception itself. A final possibility is that a population of neurones collectively encode relative times, and that exposure to a repeated timing relationship alters the balance of responses in this population. Here, we simplified each of these explanations to its core features in order to produce three corresponding six-parameter models, which generate contrasting patterns of predictions about how simultaneity judgements should vary across four adaptation conditions: No adaptation, synchronous adaptation, and auditory leading/lagging adaptation. We tested model predictions by fitting data from all four conditions simultaneously, in order to assess which model/explanation best described the complete pattern of results. The latency-shift and criterion-change models were better able to explain results for our sample as a whole. The population-code model did, however, account for improved performance following adaptation to a synchronous adapter, and best described the results of a subset of observers who reported least instances of synchrony., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Audiovisual timing perception can recalibrate following prolonged exposure to asynchronous auditory and visual inputs. It has been suggested that this might contribute to achieving perceptual synchrony for auditory and visual signals despite differences in physical and neural signal times for sight and sound. However, given that people can be concurrently exposed to multiple audiovisual stimuli with variable neural signal times, a mechanism that recalibrates all audiovisual timing percepts to a single timing relationship could be dysfunctional. In the experiments reported here, we showed that audiovisual temporal recalibration can be specific for particular audiovisual pairings. Participants were shown alternating movies of male and female actors containing positive and negative temporal asynchronies between the auditory and visual streams. We found that audiovisual synchrony estimates for each actor were shifted toward the preceding audiovisual timing relationship for that actor and that such temporal recalibrations occurred in positive and negative directions concurrently. Our results show that humans can form multiple concurrent estimates of appropriate timing for audiovisual synchrony.

Background: Different sources of sensory information can interact, often shaping what we think we have seen or heard. This can enhance the precision of perceptual decisions relative to those made on the basis of a single source of information. From a computational perspective, there are multiple reasons why this might happen, and each predicts a different degree of enhanced precision. Relatively slight improvements can arise when perceptual decisions are made on the basis of multiple independent sensory estimates, as opposed to just one. These improvements can arise as a consequence of probability summation. Greater improvements can occur if two initially independent estimates are summated to form a single integrated code, especially if the summation is weighted in accordance with the variance associated with each independent estimate. This form of combination is often described as a Bayesian maximum likelihood estimate. Still greater improvements are possible if the two sources of information are encoded via a common physiological process., Principal Findings: Here we show that the provision of simultaneous audio and visual speech cues can result in substantial sensitivity improvements, relative to single sensory modality based decisions. The magnitude of the improvements is greater than can be predicted on the basis of either a Bayesian maximum likelihood estimate or a probability summation., Conclusion: Our data suggest that primary estimates of speech content are determined by a physiological process that takes input from both visual and auditory processing, resulting in greater sensitivity than would be possible if initially independent audio and visual estimates were formed and then subsequently combined.

Humans exist in an environment wherein many unrelated events occur in close spatial and temporal proximity. Audio-visual timing experiments, however, have often examined only isolated pairs of sensory events. We therefore decided to assess how audio-visual timing perception would be shaped by the presence of an additional audio or visual event. We found that the point of subjective synchrony for a sensory event can be shifted away from the presence of other temporally proximate events. These interactions made audio-visual pairs seem unrelated, or asynchronous, at timings at which they had seemed synchronous when presented in isolation. This shows that the interval across which humans are insensitive to audio-visual asynchrony is not fixed, but dynamic, shaped by interactions between multiple sensory events. Importantly, we establish that these interactions can enhance the sensitivity of timing judgments. These interactions could therefore help to segregate unrelated sensory events across time. Such effects are likely to be common in the cluttered environments in which humans exist.

It has been proposed that there is a perceptual compensation for the difference between the speeds of light and sound. We examined this possibility using a range of auditory-visual tasks, in which performance depends on the relative timing of auditory and visual information, and manipulated viewing distance to test for perceptual compensation. We explored auditory-visual integration, cross modal causal attributions, and auditory-visual temporal order judgments. We observed timing shifts with viewing distance following loudspeaker, but not headphone, presentations. We were unable to find reliable evidence of perceptual compensation. Our findings suggest that auditory and visual signals of an event that reach an observer at the same point in time tend to become perceptually bound, even when the sources of those signals could not have occurred together.

Items in working memory are typically defined by various attributes, such as colour (for visual objects) and pitch (for auditory objects). The attribute of duration can be signalled by multiple modalities, but has received relatively little attention from a working-memory perspective. While the existence of specialist stores (e.g., the phonological loop and visuospatial sketchpad) is often asserted in the wider working-memory literature, the interval-timing literature has more often implied a unitary (amodal) store. Here we combine two modelling frameworks to probe the basis of working memory for duration; a Bayesian-observer framework, previously used to explain behaviour in duration-reproduction tasks, and mixture models, describing distributions of continuous reports about items in working memory. We modelled different storage mechanisms, such as a limited number of fixed-resolution slots or a resource spread between items at a cost to resolution, in order to ask whether items from different sensory modalities are maintained in separate, independent stores. We initially analysed data from 32 participants, who memorised between one and eight items before reproducing the duration of a randomly selected target. In separate blocks, items could be all visual, all auditory, or an alternating mixture of both. A small control experiment included a further condition with precuing of target modality. Certain kinds of slot models, resource models, and combination models incorporating both mechanisms could account for the data. However, looking across all plausible models, the decline in performance with increasing memory load was most consistent with a single store for event durations, regardless of stimulus modality. [ABSTRACT FROM AUTHOR]

Determining if we, or another agent, were responsible for a sensory event can require an accurate sense of timing. Our sense of appropriate timing relationships must, however, be malleable as there is a variable delay between the physical timing of an event and when sensory signals concerning that event are encoded in the brain. One dramatic demonstration of such malleability involves having people repeatedly press a button thereby causing a beep. If a delay is inserted between button presses and beeps, when it is subsequently taken away beeps can seem to precede the button presses that caused them. For this to occur it is important that people feel they were responsible for instigating the beeps. In terms of their timing, as yet it is not clear what combination of events is important for motor-sensory temporal recalibration. Here, by introducing ballistic reaches of short or longer extent before a button press, we varied the delay between the intention to act and the sensory consequence of that action. This manipulation failed to modulate recalibration magnitude. By contrast, introducing a similarly lengthened delay between button presses and consequent beeps eliminated recalibration. Thus it would seem that the critical timing relationship for motor-sensory temporal recalibration is between tactile signals relating to the completion of an action and the subsequent auditory percept. [ABSTRACT FROM AUTHOR]