Figure 4.

Explaining VSTM resolution from a neural perspective. (A) During image perception, high-resolution representations are formed in primary, visual cortex (V1–V3; in yellow). In higher visual areas (V4/IT; in blue), the receptive field size of neurons becomes larger and as a consequence, the resolution of representations becomes more limited (shown as a blur). Spatial attention (in red), subserved by the superior parietal lobe (SPL) and the frontal eye fields (FEF), imposes even stricter capacity limits on the amount of information that can be represented (shown as four location slots). Finally, central attention (in green), speculatively subserved by the dorsolateral prefrontal cortex (DLPFC), can only be directed to one item at a time. A major assumption of the model is that all forms of visual short-term memory depend on recurrent processing. (B) Representations at the lowest level in the visual hierarchy are high-resolution or visually detailed representations that support change detection and identification, whereas representations at higher levels in the hierarchy are more abstract representations and support change detection or identification only. Just after stimulus off-set, many representations exist at the V1–V3 level and these representations are available for report when an early retro-cue, measuring iconic memory, is shown. As time passes, activity at the V1–V3 level comes to a stop. As a consequence, less high-resolution representations are available for report when a late retro-cue, measuring fragile VSTM, is shown. Finally, after visual interference by the test display, all representations at the V1–V3 and the V4/IT level are overwritten. Only the representation that has received top–down spatial and central attention is completely protected against interference. In addition, representations that have received top–down spatial attention are protected at the V4/IT level.