Posner Cueing Task

The Posner cueing task measures how quickly attention moves to a location that has just changed. Two boxes sit to the left and right of a central cross. One box brightens for 100 ms, or both boxes brighten on neutral trials, and a dot then appears in one box 100, 200 or 300 ms after the flash began. Participants press F for a dot in the left box and J for a dot in the right box, as quickly and accurately as they can.

On 60% of trials the dot appears in the flashed box (valid cue), on 20% in the other box (invalid cue), and on 20% both boxes flash (neutral cue). Target side and cue-target interval are balanced within each cue type, and every session runs a recorded random order after 10 practice trials with feedback. Responses are usually faster after valid cues than after invalid cues. The orienting cost is the invalid minus valid mean response time on correct trials.

The cue is a sudden brightening at a location, not an arrow, so it captures attention without a strategy. Intervals of 300 ms or less keep each target inside the early benefit of such a cue, before inhibition of return (Posner & Cohen, 1984). Because participants report the dot's side, a valid cue also favors the matching key, so the orienting cost includes a small response-priming component.