Effect of Spatial Frequency and Filter Condition on Visual Imagery VIvidness

Abstract

Mental imagery has been characterized as the isolation of the feedback process that occurs during normal perception, since stimuli are “perceived” without actual feedforward sensory input. Predictive coding theory has been used to explain, among other phenomena, visual perception and visual imagery, and the theory makes several predictions about the phenomenological experience of visual imagery, which is most often weak and blurry when compared with the crisp and clear experience of visual perception. Specifically, we expected imagery strength to decrease with increasing spatial frequency, and that low-pass filtered stimuli would allow for greater imagery strength than high-pass filtered and non-filtered stimuli. To test these hypotheses, 16 participants completed two experiments using a binocular rivalry paradigm. Participants’ imagery strength was operationalized as the percentage of trials where the imagined stimulus matched the dominant stimulus during rivalry. In Experiment 1, there were no significant differences between the imagery strength of low, medium, and high spatial frequency stimuli. In Experiment 2, imagery strength of low-pass filtered stimuli was not significantly different than that of high-pass filtered and non-filtered stimuli. For both experiments, participants’ overall imagery strength was not correlated with their total score on the Vividness of Visual Imagery Questionnaire 2 (VVIQ2). Taken together, these results show that spatial frequency and filter condition are stimulus properties that cannot affect strength of visual imagery. The conclusions of this study fail to verify the predictions about the nature of mental images made by the predictive coding theory of brain function.