Purchase this article with an account.
Shiau-Hua Liu, Barbara Anne Dosher, Zhong-Lin Lu; Spatially cued visual attention for precise discriminations may narrow the template as well as excluding external noise: An elaborated perceptual template model. Journal of Vision 2009;9(8):197. doi: 10.1167/9.8.197.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Spatially cued visual attention allows an observer to more effectively select the information relevant to a discrimination. Attention has been measured in external noise for contrast-limited rather than precision-limited discriminations, where external noise exclusion is the primary reported mechanism of attention. What role can attention play when discriminations are precision- as well as contrast-limited? In four observers, we measured the effect of validly cuing one of four locations at 5 deg in the periphery compared to invalid cuing for orientation discriminations of four different precisions (±4, 8, 16, or 45 deg) in zero external noise and in high external noise. This generates 16 9-point contrast psychometric functions per observer. The effects of judgment precision and of attention were assessed within the context of an elaborated perceptual template model (ePTM, Jeon, Lu, & Dosher, 2008), an observer model that integrates the effects of non-orthogonal discriminations, contrast, and external noise. Validity of attentional cuing allowed the exclusion of external noise, as previously reported (Dosher & Lu, 2000). The precision of judgment also had very large effects on performance - systematically shifting the contrast-psychometric functions to the right (higher 75% thresholds), lowering the slope and reducing the asymptotic accuracies of performance of the psychometric functions. The effects of attention were generally smaller in the lowest-precision ±45 deg condition. For 3 of 4 observers, attention narrowed the estimated width of the tuning function, explicitly supporting the proposals of Liu, Dosher & Lu (2008) in object-attention. The ePTM provided an excellent account of the full pattern of performance across all levels of attention, precision, external noise, and signal contrast with attention-dependent factors on tuning, including effects on external noise, and (in a few cases) internal noise exclusion. This model provides distinct explanations for attention effects in a wide range of stimulus conditions.
This PDF is available to Subscribers Only