Why rare targets are slow: Evidence that the target probability effect has an attentional locus
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Why rare targets are slow: Evidence that the target probability effect has an attentional locus Nicholas Hon & Chia-Howe Tan
Published online: 12 March 2013 # Psychonomic Society, Inc. 2013
Abstract Target probability has a well-known effect on detection times: Targets that occur with lower probability are detected more slowly than their higherprobability counterparts. A long-standing issue of interest is what causes this effect. In the two experiments of this study, we examined the possibility that the target probability effect has an attentional locus. We report two key findings that are consistent with this hypothesis. First, we observed a magnification of the effect when the attentional resources available for target detection were limited. Second, we also observed the complementary pattern: an attenuation of the effect when more attentional resources were available for detection. We propose that the target probability effect is caused by an asymmetry in the attentional demands made by targets that occur with different probabilities, with low-probability targets being more attentionally demanding than high-probability ones. Keywords Attention . Target Detection . Target Probability
Introduction It is well-known that target probability has a strong influence on behavior. For example, recent studies utilizing the visual search paradigm have demonstrated that infrequently appearing target stimuli are more likely to be missed than their more frequently occurring counterparts (Wolfe et al., 2007). However, it is also true that, even in situations in which accuracy is perfect or close to perfect, target probability has a pronounced effect on detection times. For example, in the simple detection paradigm, in which stimuli N. Hon (*) : C.-H. Tan Department of Psychology, National University of Singapore, 9 Arts Link, Singapore 117570, Singapore e-mail: [email protected]
are presented one at a time and detection accuracy is extremely high, the standard observation is that infrequently occurring targets are detected more slowly than more frequently occurring ones (Laberge & Tweedy, 1964; Miller & Pachella, 1973). This effect of target probability on response times (RTs), especially when accuracy is very high, is of central interest to this report. Accordingly, in the present study, we utilized the detection paradigm described above. Much of the behavioral research on the target probability effect (TPe) has focused on isolating its locus. Various proposals have implicated peripheral operations, such as perceptual- and response-level processing in the TPe. For example, one idea is that the TPe is caused by a perceptual advantage enjoyed specifically by higher-probability targets (Biederman & Zachary, 1970; Dykes & Pascal, 1981; Lau & Huang, 2010; Menneer, Donnelly, Godwin, & Cave, 2010; Orenstein, 1970). An alternative proposal is that the TPe is caused by differences in the levels of response preparation associated with high- and low-probability targets, with observers being more prepared to respond to highprobability
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