Abstract
We have previously argued that visual mental images are not substitutable for visual percepts, because the interfering effects of visual stimuli such as line maskers on visual targets differ markedly in their properties from the interfering effects of visual images (the “Perky effect”). Imagery interference occurs over a much wider temporal and spatial extent than masking, and unlike masking, image interference is insensitive to relative orientation. The lack of substitutability is theoretically interesting because the Perky effect can be compared meaningfully to real line masking in that both types of interference are visual, not due to optical factors (accommodative blur or poor fixation) or to high-level factors (attentional distraction, demand characteristics, or effects of uncertainty). In this report, however, we question our earlier position that spatial extents of interference are markedly different: when images and real lines are matched in contrast, which was not done previously, their interference effects have very similar spatial extents. These data add weight to the view that spatial properties of images and percepts are similar in respect to extent. Along with the wider temporal extent and the insensitivity to orientation, the new results remain compatible with our older hypothesis that to create a clear mental image in a region of visual space, incoming signals from the eye must be suppressed (Craver-Lemley and Reeves, 1992). We have pursued this idea in this report using “unmasking,” in which adding elements to the visual image in the region beyond the zone of suppression reduces the Perky effect.
Highlights
Whether or not visual mental images act like visual percepts is a fascinating and important question in cognitive science
We argued in favor of analogous spatial behavior but against substitutability (Arterberry et al, 2002), based on empirical findings concerning the so-called Perky effect, in which visual images, analogous to real masking stimuli, can suppress perception of real visual targets
This finding for imagery appears to agree with the literature concerning the effects of contrast polarity on acuity for real stimuli, but this agreement is not definitive as EXPERIMENT 3 If the analogy between real and imagined lines does hold up, at least for extent if not for orientation, it is possible that imagined lines, like real ones, might show “unmasking” In this phenomenon, a real mask superimposed on the target has its masking effect reduced by adding a distant mask, even when the latter had little direct effect on target visibility (Haber, 1970)
Summary
Whether or not visual mental images act like visual percepts is a fascinating and important question in cognitive science Should they have the same functions and share the same anatomy, as has been argued from imaging studies of cortical area V1, one might expect them to be mutually substitutable or at least, analogous to each other. When the target was flashed, it was presumably presented at the same location in visual space that the image already occupied (the image-on-target, or “ON” condition) Such images always interfere with perception of the target by lowering sensitivity, not by making the response criterion sub-optimal. We adopted an acuity target as the www.frontiersin.org
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
