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Visual Imagery Facilitates Visual Perception: Psychophysical Evidence


Ishai, A; Sagi, D (1997). Visual Imagery Facilitates Visual Perception: Psychophysical Evidence. Journal of Cognitive Neuroscience, 9(4):476-489.

Abstract

Visual imagery is the invention or recreation of a perceptual experience in the absence of retinal input.The degree to which the same neural representations are involved in both visual imagery and visual perception is unclear. Previous studies have shown that visual imagery interferes with perception (Perky effect). We report here psychophysical data showing a direct facilitatory effect of visual imagery on visual perception. Using a lateral masking detection paradigm of a Gabor target, flanked by peripheral Gabor masks, observers performed imagery tasks that were preceded by perceptual tasks. We found that both perceived and imaginary flanking masks can reduce contrast detection threshold. At short target-to-mask distances imagery induced a threshold reduction of 50% as compared with perception, while at long target-to-mask distances imagery and perception had similar facilitatory effect. The imagery-induced facilitation was specific to the orientation of the stimulus, as well as to the eye used in the task. These data indicate the existence of a stimulus-specific short-term memory system that stores the sensory trace and enables reactivation of quasi-pictorial representations by topdown processes. We suggest that stimulus parameters dominate the imagery-induced facilitation at short target-to-mask distances, yet the topdown component contributes to the effect at long target-to-mask distances.

Abstract

Visual imagery is the invention or recreation of a perceptual experience in the absence of retinal input.The degree to which the same neural representations are involved in both visual imagery and visual perception is unclear. Previous studies have shown that visual imagery interferes with perception (Perky effect). We report here psychophysical data showing a direct facilitatory effect of visual imagery on visual perception. Using a lateral masking detection paradigm of a Gabor target, flanked by peripheral Gabor masks, observers performed imagery tasks that were preceded by perceptual tasks. We found that both perceived and imaginary flanking masks can reduce contrast detection threshold. At short target-to-mask distances imagery induced a threshold reduction of 50% as compared with perception, while at long target-to-mask distances imagery and perception had similar facilitatory effect. The imagery-induced facilitation was specific to the orientation of the stimulus, as well as to the eye used in the task. These data indicate the existence of a stimulus-specific short-term memory system that stores the sensory trace and enables reactivation of quasi-pictorial representations by topdown processes. We suggest that stimulus parameters dominate the imagery-induced facilitation at short target-to-mask distances, yet the topdown component contributes to the effect at long target-to-mask distances.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neuroradiology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:1997
Deposited On:22 Aug 2008 12:59
Last Modified:20 Feb 2018 08:33
Publisher:MIT Press
ISSN:0898-929X
Additional Information:Copyright: MIT Press
OA Status:Green
Publisher DOI:https://doi.org/10.1162/jocn.1997.9.4.476

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