Abstract
The perception of an external stimulus not only depends upon the characteristics of the stimulus but is also influenced by the ongoing brain activity prior to its presentation. In this work, we directly tested whether spontaneous electrical brain activities in prestimulus period could predict perceptual outcome in face pareidolia (visualizing face in noise images) on a trial-by-trial basis. Participants were presented with only noise images but with the prior information that some faces would be hidden in these images, while their electrical brain activities were recorded; participants reported their perceptual decision, face or no-face, on each trial. Using differential hemispheric asymmetry features based on large-scale neural oscillations in a machine learning classifier, we demonstrated that prestimulus brain activities could achieve a classification accuracy, discriminating face from no-face perception, of 75% across trials. The time–frequency features representing hemispheric asymmetry yielded the best classification performance, and prestimulus alpha oscillations were found to be mostly involved in predicting perceptual decision. These findings suggest a mechanism of how prior expectations in the prestimulus period may affect post-stimulus decision making.
Highlights
There is growing evidence that the ongoing brain activity is not meaningless, but rather carries a functional significance that largely determines how an incoming stimulus will be processed [1]
Our principal aim was to investigate the role of prestimulus brain oscillations in predicting face pareidolia; we strategically focused on the prestimulus period only and performed single-trial classification employing machine learning framework using features extracted from the prestimulus brain oscillations
4 Discussion The present study investigated whether prestimulus brain oscillations could systematically predict post-stimulus perceptual decision in a face pareidolia task on a trialby-trial basis
Summary
There is growing evidence that the ongoing brain activity is not meaningless, but rather carries a functional significance that largely determines how an incoming stimulus will be processed [1]. The conscious perception formed after the presentation of a stimulus could be causally shaped by the brain responses prior to the stimulus onset. Mathewson et al [4] revealed the influence of oscillatory microstates of cortical activity, manifested by alpha phase, on subsequent neural activity and visual awareness. Both alpha power and larger fixation-locked ERPs are predictive of the detectability of masked visual targets. Several neuroimaging studies employing visual stimuli demonstrated that the strength of prestimulus ongoing oscillatory activity, mainly in the alpha band, can indicate the future behavioral responses [6,7,8,9]. Prestimulus brain states have been shown to predict perceptual decisions [10,11,12] while resolving perceptual ambiguity to form a conscious
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