Figure 1.

a) The figure illustrates the task used to obtain an estimate of WMC in the absence of distraction. Participants were asked to remember the positions of five red target circles displayed for 1 s followed by a delay period of 3 s (during which a white fixation cross was shown) and respond to a probe stimulus (a question mark presented for 2 s) which asked participants to indicate whether a red target circle had been shown in the position indicated (a yes/no response). Targets were positioned such that no more than two targets were in adjacent positions. The probe was shown either in or adjacent to one of the target positions. Forty trials were given, with half of the probes presented in a target position and half presented in a position adjacent to a target position. b through d) The three conditions used to obtain estimates of distractor filtering ability at encoding and delay. Target circles were displayed for 1 s, with no more than two of the targets in adjacent positions. The circular grid remained on the screen throughout each trial. A probe (a white question mark) was shown either in or adjacent to one of the target positions for 2 s, 3 s after the target stimuli had disappeared. b) In the “no distraction” condition participants were required to remember the locations of three red target circles, and no distractors appeared. c) In the “encoding distraction” condition two yellow distractor circles were shown together with the three red target circles. One of the yellow distractor circles was always in a position adjacent to a target position. d) In the “delay distraction” condition two yellow distractor circles were shown during the delay period, 0.5 s after the red target circles had disappeared. One of the yellow distractor circles was always in a position adjacent to a target position. Participants were asked to remember the positions of only the red target circles, and give a yes/no response to indicate whether the probe was in a position that had been occupied by a red target circle.