Abstract
Visual working memory (WM) is an active storage system into which visual information can be encoded to make it resistant to interference from new perceptual input. Information about simple stimuli colors, orientations is encoded into visual WM rapidly: in under 100ms, WM fills up, revealing a stark capacity limit of 3-4 items. However, for real-world objects, the same limits do not hold: with increasing encoding time, observers store more real-world objects and do so with more detail (Brady et al., 2009). We tested whether the benefit of extra time for real-world objects reflects active WM storage, or whether this benefit instead reflects the consolidation of information into long-term memory (LTM), as is traditionally assumed (e.g., Cowan, 2001; Lin & Luck, 2012). To address this directly, we measured the contralateral delay activity (CDA) a marker of WM capacity, which reflects active storage of visual information in the parietal lobe (Vogel & Machizawa, 2004). We manipulated encoding time (200ms and 1s) for real-world objects and found that: (1) the CDA continues to build in strength during the entire 1s encoding interval, and (2) this results in a CDA that is significantly larger after 1s than after 200ms (t(11)=2.8, p=0.01). This shows that the ability to remember more information about real-world objects with increased encoding time does not merely reflect LTM consolidation, but reflects active storage in WM. These results demonstrate that WM shows different properties for simple stimuli and real-world stimuli, and suggest that more work is needed to understand the properties of the WM system as we use it in the real world.
Meeting abstract presented at VSS 2014