Negative Priming

Negative priming is the finding that a person responds more slowly, or less accurately, to a stimulus that they had previously been instructed to actively ignore on an immediately preceding trial, compared to a stimulus that had not appeared at all beforehand, an effect that runs opposite in direction to ordinary priming, in which prior exposure to a stimulus usually speeds up rather than slows down later responses to it. In a typical demonstration, participants view two overlapping items on one trial and must respond only to a designated target while ignoring the other, distractor item, and researchers then measure responses on a following trial in which the earlier distractor unexpectedly becomes the new target, consistently finding a measurable slowing compared to a fully novel item. The psychologist Steven Tipper conducted influential research clarifying the effect from the mid-1980s onward, and negative priming is generally interpreted as evidence that selective attention does not simply amplify a chosen target while passively letting an ignored distractor fade away, but instead actively suppresses or inhibits the mental representation of that distractor, leaving a residual inhibitory trace that then has to be overcome when the same item later needs to be attended to and responded to correctly. The effect has been an important source of evidence in debates over whether selective attention operates primarily by enhancing wanted information, suppressing unwanted information, or some combination of both mechanisms working together.