Attention Experiments

1. 12 stimuli arranged around a foveal point to display target and distractors in.

2. Each of the 12 items has a gabor patch within it. This can be horizontal/vertical (6,6) in orientation. The subject has to find the gabor patch in the target and indicate it's orientation by using 2 specified keys.

3. A property of the distractor is varied from trial to trial. This can be color, shape or size. But the target color is varied once a day over the course of 3 days.

The participant's task on each trial is to report the direction (vertical/horizontal) of a Gabor patch in a cued stimulus (the "target"). The stimuli are defined by three features: color, size, and shape. There are three sessions, and the feature that serves as cue changes with each session, e.g., the target is a square with circular foils in session 1, red with green foils in session 2, and big with small foils in session 3. The location of the target in the display is randomly (i.i.d.) selected on each trial. There may be zero, one, or two distractors on each trial. These distractors have a different value of one of the two uncued features. E.g., if the cued feature is color (red target with green foils), one distractor might be a larger green circle (different size) and another might be a green square (different shape). The locations of the distractors, if any, are also randomized on each trial.

50% of trials have two distractors (to make sure that there is enough data in this condition), 1/3 of trials have one distractor (evenly split between the two uncued features) and 1/6 of trials have no distractor. Participants will see a fixation cross for about 1 sec., the circular stimulus array will appear, and participants will make their response as quickly as possible. The participants are given feedback about the experiment as motivation.