Fig. 1.

Search stimuli. Visual search stimuli comprised a uniform grey background with an array of randomly rotated white letter L distractors equally spaced in a concentric ring, around a central white fixation cross. On target present trials one of the distractors was replaced by a randomly rotated letter T. Participants were required to report the presence or absence of the rotated letter T as fast and as accurately as possible. Two set sizes were used, n = 4 (T4) and n = 10 (T10)