AN INHIBITION-BASED FAN EFFECT - EVIDENCE FOR AN ACTIVE SUPPRESSION MECHANISM IN SELECTIVE ATTENTION

Abstract An inhibition-based fan effect hypothesis was tested using a negative priming paradigm in Experiments I and 2 and a short-term memory scanning paradigm in Experiment 3. In Experiment I and 2, the time to name a letter (surrounded by I to 3 distractor letters) was longer when it had been a distractor on the previous display than in a control condition where the target letter had not been one of the distractors in the previous display. This negative priming effect attenuated as the number of distractors in the previous display increased. We interpret this fan effect as a manifestation of a limited capacity spreading inhibition counterpart to spreading activation. Median split data, isolating faster from slower subjects, suggested that an irrelevancy heuristic may be involved because the best performances (fastest overall RTs) were produced by people who also produced relatively greater magnitudes of negative priming. By having irrelevant information momentarily less available, overall advantages in processing appear to be gained through reduced interference from distracting stimuli. The juxtaposition of an irrelevancy with a relevancy heuristic (Anderson, 1983a) supports the possible existence of a spreading inhibition counterpart of spreading activation. Several key predictions based upon this framework were confirmed in a modified short-term memory scanning task in Experiment 3.