Abstract:

Are temporal expectation created passively and purely unintentionally when we are exposed to rhythmic patterns? Previous studies using dual-task paradigm have found that temporal expectancy induced by regular auditory events sequence was resistant to working memory (WM) interference. However, the paces of the events sequence were fast in these studies. There may involve different processes between the range of sub-seconds and supra-seconds. Therefore, in the current study, we used dual-task paradigm to investigate whether participants could develop temporal expectancy driven by auditory isochronous rhythmic events sequence with slow rate paces, and further to test whether this effect could survive the interference of WM task with two different experiments. A total of 65 subjects participated in two experiments, with 31 in experiment one and 34 in experiment two. In both experiments, participants were told that the auditory sequences were irrelevant with tasks, and they just need to ignore them. In Experiment 1, auditory events in a sequence separated by a fixed (650ms regular condition) or jittered (350/650/950/1250/1550ms irregular condition) intervals. In single task condition, participants were required to finish a reaction time task, pressing button “B” to respond to auditory target (400Hz, 100ms) presented after a regular or an irregular sequence of auditory stimuli. In dual-task condition, participants had to concurrently finish a counting WM task. The WM task consisted of remembering how many times each color appeared during a block of trials. At the end of each block, participant should type how many times a certain color had been presented. Each color was selected randomly, with the same probability for the memory test. The three-way repeated measures analysis of variance (ANOVA) was conducted on rhythm (regular vs. irregular sequence) and foreperiods, the intervals between the end of auditory sequence and onset of targets (650ms, 950ms, vs. 1250ms), as within-subjects factors, with task (single & dual-task) as between-subjects factors. The results revealed that participants responded faster after regular compared with irregular sequences. In addition, the interaction between rhythm and task was not significant, which meant that the temporal expectancy effect was not affected by WM task. However, auditory events sequence and targets were both presented in auditory modality in Experiment 1. Participants might notice the auditory events sequence more or less while they responded to targets, even though they were told to ignore the sequences. In order to draw attention away from auditory sequences as far as possible, we replaced auditory targets with visual targets in Experiment 2. The results from repeated ANOVA revealed that there was no a significant interact between rhythm and task. More specifically, dual-task did not affect temporal expectancy induced by rhythms, with faster RTs after regular than those after irregular sequences. The present study confirmed previous finding that temporal expectancy effect survived the interference of the WM task. Furthermore, our results extended this effect to vision modality. Taken together, our results suggested that rhythmic temporal expectation may involve bottom-up process and is independent of cognitive control process.