Cross-Talk Between Visual Short-Term Memory and Low-Level Vision: Evidence for Interactions Across Shared Neural Resources.
16.41, Friday, May 10, 5:30 - 8:00 pm, Orchid Ballroom
Nicholas M. Van Horn1, Alexander A. Petrov1; 1Department of Psychology, Ohio State University
Visual short-term memory (VSTM) is often characterized as a temporal buffer whose content is protected from subsequent visual input. However, recent human and monkey studies suggest that VSTM shares overlapping neural resources with low-level vision and is subject to interference from visual input. The present study used tilt aftereffects to reveal the reciprocal to also be true: VSTM can augment perception, thus creating distorted perceptions relative to the ground truth. Method: For twelve observers, three Gabors Sample, Target, & Match were presented sequentially on each trial. In VSTM blocks, observers held the orientation of the Sample in VSTM and reproduced it later by manipulating the Match. In control blocks, the Sample was viewed for the same amount of time, but reappeared during the Match phase. The dependent variable of interest was response bias on a binary CW/CCW discrimination task involving the Target Gabor sandwiched between the Sample and Match. Unbeknownst to the subjects, the Target orientation was always exactly vertical. A concurrent attentional task forced observers to foveate the Sample. Results: The responses on the CW/CCW task were biased away (~59%) from the Sample orientation in the control condition, indicating a tilt aftereffect as expected. The new result is that the response bias was twice as strong (~68%) in the VSTM condition. Conclusion: This demonstrates that visual perception is not fully insulated from VSTM. Rather, VSTM interference can systematically alter subsequent visual processing. One potential explanation is that memory for stimulus features is subserved by connections from well-known VSTM cortical sites (e.g., prefrontal cortex) that overlap with circuits involved in the encoding of low-level stimulus features (e.g., occipital lobe). By sharing neural resources to economize representational space, the two systems are subject to cross-talk.