FIGURE 1.

The visual feature conjunction task. Subjects performed a visual feature conjunction task with colored letters (blue P, blue F, orange P, or orange F) subtending 0.5° of visual angle randomly presented to the left or right hemifield, 1.6° from the fixation cross. Stimulus durations were 200 ms. Right-handed subjects pressed the left mouse button for targets (blue P’s, probability 40%) and pressed the right mouse button for non-targets, i.e., letters which resembled the target in color, shape, or neither feature (probability 20% each). The response button could be spatially compatible (trials 1 and 2) or spatially incompatible (trial 3) with the stimulus visual field. Stimulus onset asynchronies (SOAs) began at 2500 ms and were either reduced by 3% following each pair of successive hits or increased by 3% following each miss. From Woods et al. (2015c).