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Howard Yang, Peng Sun, Charles Chubb, George Sperling; Complex Attention Filters for Low Contrast Items. Journal of Vision 2016;16(12):681. doi: 10.1167/16.12.681.
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Drew et al. (JOV 2010) found that in estimating the centroid (center-of-gravity) of a random cloud of dots varying in grayscale, observers can give approximately equal attentional weight to all dots. Yang, Sun, Chubb, & Sperling (VSS 2013) found observers can estimate centroids giving weight proportional to contrast magnitude to all dots as well as just the light (dark) dots, ignoring dark (light) dots. Here we ask whether observers can weight dots in inverse proportion to contrast magnitude. Method. Stimuli were random dot clouds comprising 8 or 16 dots varying in Weber contrast. In a given attention condition, the observer strove to mouse-click the centroid of the dot-cloud, weighting dots in accordance with a specified target filter defined by (1) a target-dot set and (2) a weighting rule. There were three target-dot sets: All-dots, Dark-only (dots darker than the background), Light-only (dots lighter than the background). There were also three weighting rules: weight target dots equally (E-weight), in proportion to contrast magnitude (P-weight), or in inverse proportion to contrast magnitude (I-weight). (All involved giving weight 0 to non-target dots.) Results. Performance in the E-weight and P-weight conditions revealed high efficiency and filter accuracy. Attention filters achieved in the I-weight conditions differed strikingly from those achieved in the E and P-weight conditions. In particular, for single polarity Dark-only and Light-only target sets, the attention filters achieved in the I-weight condition matched the target filter well, and performance was moderately efficient. Strikingly, for Dark/Light-only targets with both polarities, observers were able to filter out non-target dots nearly perfectly. Performance was worse for the All-dots target set (Os had difficulty achieving attention filters that matched the target filter, and efficiency was lower). Conclusion. Os can achieve efficient attention filters selective for a single contrast polarity that weight dots in inverse proportion to contrast magnitude.
Meeting abstract presented at VSS 2016
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