Cross-modal temporal recalibration guarantees stable temporal perception across ever-changing environments. Yet, the mechanisms of cross-modal temporal recalibration remain unknown. Here, we conducted an experiment to measure how participants’ temporal perception was affected by exposure to audiovisual stimuli with constant temporal delays that we varied across sessions. Consistent with previous findings, recalibration effects plateaued with increasing audiovisual asynchrony (nonlinearity) and varied by which modality led during the exposure phase (asymmetry). We compared six observer models that differed in how they update the audiovisual temporal bias during the exposure phase and in whether they assume a modality-specific or modality-independent precision of arrival latency. The causal-inference observer shifts the audiovisual temporal bias to compensate for perceived asynchrony, which is inferred by considering two causal scenarios: when the audiovisual stimuli have a common cause or separate causes. The asynchrony-contingent observer updates the bias to achieve simultaneity of auditory and visual measurements, modulating the update rate by the likelihood of the audiovisual stimuli originating from a simultaneous event. In the asynchrony-correction model, the observer first assesses whether the sensory measurement is asynchronous; if so, she adjusts the bias proportionally to the magnitude of the measured asynchrony. Each model was paired with either modality-specific or modality-independent precision of arrival latency. A Bayesian model comparison revealed that both the causal-inference process and modality-specific precision in arrival latency are required to capture the nonlinearity and asymmetry observed in audiovisual temporal recalibration. Our findings support the hypothesis that audiovisual temporal recalibration relies on the same causal-inference processes that govern cross-modal perception.

Temporal perceptual learning (TPL) refers to improved temporal performance as a result of training with sub-second intervals. Most studies on TPL have focused on empty intervals (i.e. intervals marked by two brief stimuli); however, scholars have suggested that filled intervals (i.e. intervals presented as continuous sensory inputs) might have different underlying mechanisms. Therefore, the current study aimed to test whether empty and filled intervals yield similar TPL performance and whether such learning effects could transfer mutually. To this end, we trained two groups of participants with empty and filled intervals of 200 ms for four days, respectively. We found that the empty-interval group clearly improved their timing performances after training, and such an effect transferred to filled intervals of 200 ms. By contrast, the filled-interval group had neither learning nor transfer effect. Our results further shed light on the distinct mechanisms between empty and filled intervals in time perception while simultaneously replicating the classical findings on TPL involving empty intervals.

When a visual stimulus flickers periodically and rhythmically, the perceived duration tends to exceed its physical duration in the peri-second range. Although flicker-induced time dilation is a robust time illusion, its underlying neural mechanisms remain inconclusive. The neural entrainment account proposes that neural entrainment of the exogenous visual stimulus, marked by steady-state visual evoked potentials (SSVEPs) over the visual cortex, is the cause of time dilation. By contrast, the saliency account argues that the conscious perception of flicker changes is indispensable. In the current study, we examined these two accounts separately. The first two experiments manipulated the level of saliency around the critical fusion threshold (CFF) in a duration discrimination task to probe the effect of change saliency. The amount of dilation correlated with the level of change saliency. The next two experiments investigated whether neural entrainment alone could also induce perceived dilation. To preclude change saliency, we utilized a combination of two high-frequency flickers above the CFF, whereas their beat frequency still theoretically aroused neural entrainment at a low frequency. Results revealed a moderate time dilation induced by combinative high-frequency flickers. Although behavioral results suggested neural entrainment engagement, electroencephalography showed neither larger power nor inter-trial coherence (ITC) at the beat. In summary, change saliency was the most critical factor determining the perception and strength of time dilation, whereas neural entrainment had a moderate influence. These results highlight the influence of higher-level visual processing on time perception.

Rhythmic visual stimulation can cause neural entrainment, the synchronization of intrinsic oscillations and the external stimulus rhythms. Neural entrainment has been reported to modulate perceptual processes, such as enhancing perceived brightness and facilitating temporal prediction. However, flicker-induced neural entrainment effect is confounded by change saliency, the subjective perception of stimulus changes. It remains unclear whether neural entrainment without change saliency could influence visual perception. To preclude change saliency, we used frequencies higher than the critical fusion threshold to render flicker perception stable. Importantly, we simultaneously presented two flickers at 55.5 Hz and 62.5 Hz while measuring electroencephalography to assess whether their beat frequency (i.e., 7 Hz) arose by the nonlinear processing at the visual cortex. To test the influence of neural entrainment at the beat, we used this combined flicker in a duration discrimination task with a two-alternative forced-choice design. In this task, 17 participants compared seven durations of the combined flicker with the standard duration of a stable stimulus. Behavioral results revealed that the combined flicker induced time dilation, supporting the engagement of neural entrainment. We also conducted the power analysis, inter-trial coherence analysis, and rhythmic entrainment source separation that could increase the signal-to-noise (SNR) ratio of SSVEPs. The SNR at the lower fundamental frequency was significantly larger than the control condition, suggesting that the neural entrainment of fundamental frequencies was successful. We concluded that neural entrainment could influence visual perception without the conscious perception of stimulus changes, while stronger neural entrainment methods are needed to further examine the existence of the beat derived from high frequencies.

Music notation and English word reading have similar visual processing requirements. It remains unclear how the two skills influence each other. Here we investigated the modulation of music reading expertise on visual processing of English words through an ERP study. Participants matched English real, pseudo, and non-words preceded by musical segments or novel symbol strings in a sequential matching task. Musicians showed smaller N170 amplitude in response to English non-words preceded by musical segments than by novel symbol strings in the right hemisphere. This effect was not observed in real or pseudo-words, or in any of nonmusicians’ responses. Similar to English non-words, musical segments do not have morphological rules or semantic information, giving rise to this modulation effect. This finding suggested a shared visual processing mechanism in the right hemisphere between music notation and English non-word reading, which may be related to serial symbol processing as suggested by previous studies.