Implicit Learning Of Temporal Rhythm

Implicit learning refers to the learning process without consciousness.Through implicit learning,humans can acquire knowledge of structural regularities of events or objects automatically from the environment.Implicit learning is of great significance to the adaptability which enables humans to adapt to regularities and contingencies inherent in the environment.Numerous studies have revealed that sequence knowledge can be learnt implicitly with classical sequence learning tasks.Participants are usually asked to respond to the sequence-based stimulus properties(such as shape,color,position,etc.).In these studies,stimulus presentation corresponds to the key response.Some researchers put forward that perceptual and motor learning may exist simultaneously in the process of implicit learning.While it is hard to dissociate the two learning components of perceptual and motor learning in the classical sequence learning task to investigate the learning effects independently.However,it remains unclear whether implicit learning is based on perceptual learning or motor learning.In the present study,a temporal-rhythm-based serial reaction time task was developed to dissociate visual and motor temporal rhythm.This research aims to clarify the learning effects of perceptual learning and motor learning in the process of implicit temporal rhythm learning.Meanwhile,time-frequency analysis was used to further investigate the relationship between specific neural oscillation and implicit temporal rhythm learning.Three experiments were executed in the present study.In experiment 1,we explored the effect of implicit temporal rhythm learning.In this experiment,visual temporal rhythm corresponds to motor temporal rhythm.The results revealed that reaction time of regular stimulus decline faster than that of random stimulus.Regular stimulus evoked stronger neural oscillation activities in theta band at 4.8-5.4 Hz compared with random stimulus.Participants were unable to verbally report the regularities of the temporal rhythm,indicating that participants implicitly acquired the knowledge of temporal rhythm.The results suggested that theta oscillation at 4.8-5.4 Hz is related to the implicit temporal rhythm learning.In experiment 2,we explored the effect of implicit visual temporal rhythm learning with the motor temporal rhythm being disturbed.The results revealed that reaction time of regular stimulus declines faster than random stimulus,which means participants learnt the visual temporal rhythm implicitly.Meanwhile,regular stimulus evoked stronger neural oscillation activities in theta band at 4.8-5.4 Hz compared to random stimulus,which is similar to experiment 1.It is suggested that theta neural oscillation is associated with implicit visual temporal rhythm learning.In experiment 3,we explored the effect of implicit motor temporal rhythm learning with the visual temporal rhythm being disturbed.There was no significant effect of motor learning since no significant difference in the learning rate between regular and random stimulus was observed.Furthermore,theta oscillation was not observed yet,indicating that theta oscillation is irrelated to motor temporal rhythm.By further comparing the results of all three experiments.It was found that the learning rate of experiment 1 did not differ from that of experiment 2,but experiments 1 and 2 were significantly larger than that of experiment 3.It suggests that visual temporal rhythm plays an important role in the process of implicit temporal learning.The power difference of theta oscillation at 4.8-5.4 Hz between regular and random stimulus revealed that experiment 1 did not differ from that of experiment 2,but experiments 1 and 2 were significantly stronger than that of experiment 3 which means 4.8-5.4Hz theta oscillation is mainly related to implicit visual temporal rhythm learning.Taken together,the current study provides evidence that humans can learn temporal rhythm implicitly which can evoke theta neural oscillation at 4.8-5.4 Hz in the process of implicit learning.Visual temporal rhythm plays a major role in the process of implicit temporal rhythm learning which is related to theta oscillation.Besides,it suggests the importance of perceptual learning in the process of implicit temporal rhythm learning.