Abstract
Sensory recruitment models maintain that storage in working memory (WM) is accomplished via activity in the same brain regions that encoded the memoranda (e.g., Serences et al., 2009; Harrison and Tong, 2009). It follows naturally from this hypothesis that encoding acuity may be correlated with the precision of online visual memories, even if encoding quality is not a limiting factor in the memory task. For instance, encoding and storage quality may depend upon a common top-down process that guides internal and external selection. Another possibility, however, is that variance in mnemonic precision across observers is determined by the degree to which mnemonic precision falls below the ceiling set by encoding precision; in this case, encoding and mnemonic precision may not be correlated at all. To test these alternatives, we measured performance in a perceptual orientation task that required participants to match the orientation of two sine wave gradients displayed above and below fixation. In a separate VWM task, we measured visual WM precision while optimizing the encoding conditions for the memorandum. Participants remembered the orientation of a single foveally presented line (duration: 250 ms) and reported the orientation after a 1.25 second delay. Perceptual and VWM response precisions were operationalized by the standard deviation (SD) of the response offset histograms. Critically, perceptual and mnemonic precision were reliably correlated, r(35) = .537, p <0.001. Finally, EEG measurements during a visual WM task revealed that neural synchrony in the alpha-band – even when measured during the encoding period alone – provides a robust prediction of individual mnemonic precision. Thus, our findings suggest that a common neural resource may determine encoding and mnemonic precision.
Meeting abstract presented at VSS 2013