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 1 and 2, the time to name a letter (surrounded by 1 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.Resume l.'hypothcsc d'un effet d'

Three experiments examined the relative contributions of positive and negative priming in a selective attention task. A typical trial consisted of a briefly presented letter display containing a red target letter and a distractor letter of another color. This prime display was followed by another similar letter display (the probe). When the red target letters were identical in both displays, facilitation from identity repetition priming was obtained. When the unattended letter from the prime display became the probe target letter, response times were delayed, that is, a negative priming effect was found. Other combinations of target and distractor letters were manipulated to examine the relative influences of positive and negative priming. Results support the hypothesis that selective attention involves a selective inhibition mechanism and suggest that this inhibitory mechanism can be as influential as its excitatory counterpart.

Three experiments are reported that examined conceptual negative priming effects in children 5 to 12 years of age. Experiment 1 used a negative priming variant of a flanker task requiring the naming of a central color blob flanked by irrelevant distractors. Experiment 2 used a negative priming variant of the Stroop color-word task. Experiment 3 used a same-different matching task with novel 3-D shapes. Results revealed significant and equivalent magnitudes of negative priming across the tested age groups for all 3 tasks. It is concluded that the inhibitory mechanism underlying conceptual (i.e., identity or semantic) negative priming in visual selective attention tasks is intact in young children. Because the findings and conclusions diverge from the developmental literature on negative priming, the authors attempt to reconcile the contradictions by pinning down the reasons for the discrepancies.

Using randomized stimulus onset asynchrony (SOAs), the authors traced the time course of Stroop interference and facilitation in normal participants and participants with schizophrenia. Unlike earlier findings using blocked SOAs, singular peaks in interference, facilitation, or both occurred at particular SOAs. The peaks of normal participants and participants with schizophrenia differed. Findings are congruent with a model of Stroop performance that posits individual differences in processing speeds of target and nontarget stimulus dimensions, coupled with critical points in response selection. Participants with schizophrenia also showed more overall interference than normal control participants. A second experiment that added a temporal gap between the distractor word and target color obliterated Stroop effects only for individuals with schizophrenia. These findings provide a new empirical basis for models of Stroop effects. They are also consistent with hypotheses about the importance of the prefrontal cortex for working memory and prefrontal dysfunction in schizophrenia.

Two negative priming experiments in older and younger adults are reported. Participants in Experiment 1, involving both positive and negative priming conditions, showed both types of priming. There were no significant differences between age groups. If anything, older participants showed more negative priming. In Experiment 2, involving only negative priming conditions, similar results were obtained. Our findings rule out possible effects of experimental conditions that episodic retrieval theorists have suggested might account for negative priming in older adults. Although our results may be consistent with an explanation of negative priming in older adults by an expansively specified theory of episodic retrieval, they are at least as consistent with the view that inhibitory processes are intact in older adults. In light of these findings, conflicting empirical results and alternative views of negative priming in older adults are examined.