Cross-Modality Modulation Of Task-irrelevant Rhythmic Tones On Visual Rhythmic Temporal-pulse Accumulation

External stimuli from the environmental are often characterized by the degree of temporal regularity, the results of previous studies show that the rhythm of time may have an impact on cognitive activities like time perception. Dynamic attending theory provides a framework to explain how the temporal context that stimulus events occur can affect the perception of stimulus. According to this theory, if stimulus events occur in a rhythmic and isochronous stimulus sequence, the cerebral cortex neural oscillators that closely related to the allocation of attentional resources can be synchronized with external stimuli, the period of neural oscillators is adjusted to make the internal and external events to be consistent, leading to the maximize distribution of attention in an expected point, that is the entrainment of attention. Recent studies suggest that the cerebral cortex neural oscillators associated with selective attention primarily occur in low frequency bands, including delta(0.5-4 Hz) and theta(4-10 Hz). In this study, we plan to use the low-frequency(2 Hz) auditory rhythmic stimulation, to exam whether the external auditory stimulation in delta band frequency have a cross-modal entrainment on the visual temporal pulses accumulation; and whether this cross-modal entrainment in low frequency effect by the total duration of the task-relevant visual stimulation and the regularity of task-irrelevant auditory stimulation.We use three experiments to study the effects of task-irrelevant auditory rhythmic stimulation on time processing. The research paradigm of time perception is Stop-Reaction-Time task that requires subjects to observe a series of regular visual stimulation, these are isochronous stimuli, and the task of subjects is to press the key after the final signal is presented as soon as possible. The Stop-Reaction-Time task itself contains rhythmic stimulation, when compared with other time tasks, stop reaction time is not dependent on external signals, the connection between stimulus and response does not exist(each signal just simply reset temporal pulses accumulation), but rely on an internal clock pulse accumulation. At the same time, the implementation of the task is easy, there is not much of a between-trial memory requirement, and it can reflect the rhythmic pulse process. So far, there are no studies to use Stop-Reaction-Time task to answer the question:whether the exogenous auditory stimuli could modulate the temporal pulses accumulation caused by visual stimuli? What is the influence factor of this cross-modal attention entrainment? These questions leave some place to our study.In Experiment 1, subjects were presented by a series of auditory rhythmic stimulation which can be ignored, then required to complete a subsequent Stop-Reaction-Time task. The results show that, when the time task interval approaching task-irrelevant auditory rhythm interval, the reaction time difference between two auditory conditions (having tones or not) is minimum, it represented the best attention ability and accuracy of the time judgement. With the time interval deviation increasing, the difference between two auditory conditions increased gradually (showed a U-shaped form as a whole), reflecting the weakening of attention ability, that is the typical exogenous attention entrainment. This experiment showed that task-irrelevant auditory rhythm could modulate the process of time pulse accumulation in visual channel.To further investigate whether the exogenous attention entrainment caused by rhythmic stimuli could be affected by the duration of relevant time task. In experiment 2, the Stop-Reaction-Time task’s duration had two levels, short and long duration. The results showed that the duration of relevant time task had effects on entrainment. The interaction between the auditory rhythmic stimuli and the visual stimuli in time task still stayed unknown. In experiment 3, we studied whether the irregular auditory stimuli could entrain attention, the result showed that the irregular auditory stimuli can produced interference effects, but the cross-modal exogenous attention entrainment did not occur.