Experiment 1.

<p>A) All stimuli in a trial were presented to the same quadrant of the visual field. Participants had to remember stimulus S₁ (the mask) and, after a short delay, F₁ (the sample) to perform two delayed discriminations: J₁ (comparing F₁ and F₂), and J₂ (comparing S₁ and S₂). The F₁–F₂ comparison was the main task of interest and the spatial frequencies of the stimuli differed at the individually estimated 75% hit rate level. The S₁–S₂ comparison was introduced to ensure that subjects actively tried to remember the mask and differed at the estimated 85% hit rate level. The mask and sample always had orthogonal orientations to avoid priming effects. B) Behavioral results from psychophysical sessions. The graphs are normalized changes in F₁–F₂ discrimination for the three participants with respect to their individual baseline measure. C) Behavioral results from fMRI Experiment 1. Note that the two Mask/Sample (S₁/F₁) Frequency Ratios differing from one in the psychophysical experiment were combined in the analysis of the fMRI experiment. Error bars represent ±1 SE.