Figure 1. Assessing effects of exposure duration on recall of orientation.

(a) The recall task used in Exp 1. An array of colored oriented bars was presented for a variable exposure duration, followed by a pattern mask. After a blank retention interval, a probe bar appeared and subjects used a response dial to adjust its orientation to match the item with the same color in the memory array (the target). The angular difference between response and target orientations was taken as a measure of recall error.

(b) Three hypotheses regarding the evolution of recall precision with exposure time, as a function of the number of items in the memory array. Here, lighter shades indicate more items stored in memory. The top panel is based on an assumption of limited storage capacity: as more items are stored the maximum-attainable precision declines. The middle panel depicts the case of limited encoding capacity: eventually the same level of precision is reached regardless of array size. Finally, the lower panel shows expected performance when both storage and encoding capacities are limited. Compare these possible results with the actual findings in Fig 2a.