Obligatory averaging in mean size perception

Abstract

The perception of ensemble characteristics is often regarded as an antidote to an established bottleneck in focused attention and working memory, both of which appear to be limited in capacity to a few objects only. In order to test the associative law of summation, observers were asked to estimate the mean size of four circles relative to a reference circle. When there was no time to scrutinize each individual circle, observers discriminated the mean size difference identically, irrespective of whether the same summary size increment or decrement was added to or subtracted from the size of only one, two, or all four circles. Since observers judged the size of individual circles, the position of which was indicated after they were displayed, considerably less accurately than the mean size of the four circles, it is very unlikely that explicit knowledge of the size of the individual elements is the basis of mean size judgments. The sizes of individual elements were pooled together in an obligatory manner before size information had reached awareness. The processing of size information seems to be largely constrained to only one measure at a time, with a preference for mean size rather than the individual measures from which it is assembled.

Effects of ensemble complexity and perceptual similarity on rapid averaging of hue

“…This finding is concordant with both the postperceptual role for color categories in cognition (He et al, 2014) and the early and automatic nature of ensemble encoding (e.g., Allik, Toom, Raidvee, Averin, & Kreegipuu, 2014;Corbett & Oriet, 2011; and also supports our previous findings of the effect of categories on mean color familiarity (Maule et al, 2014).…”

“…This is contrasted with the prediction regarding serial, focused attention on individual elements. A basic prediction of a focusedattention account is that, assuming the number of elements sampled is constant (but see Allik et al, 2014), averaging accuracy should decline with more elements as the subsample of elements to which attention is paid is more prone to bias. Marchant et al (2013) found that adding more elements decreased accuracy of mean settings for ensembles in which each element had a unique size.…”

“…This proposition is also supported by evidence for adaptation to the mean of an ensemble (Corbett et al, 2012), evidence that ensemble means may be used as ''units'' of working memory Im, Park, & Chong, 2014) and are represented across multiple frames of reference (Corbett & Melcher, 2014a). Recent evidence also suggests that ensemble means can be used by 4-to 5-year-olds to guide their perceptual judgments (Sweeny, Wurnitsch, Gopnik, & Whitney, 2014), adding weight to the argument that ensemble coding is a pervasive feature of the visual system, and in some cases, averaging appears to be an obligatory process (e.g., Allik et al, 2014;Parkes et al, 2001), requiring little or no attention to the features in question (Alvarez & Oliva, 2008Baijal et al, 2013).…”

Ensemble statistics as units of selection

“…When there were many items to be grouped into ensembles, it seems that the selection mechanism operated at ensembles level by allocating attention to the centroid of a set of multiple items. Therefore, the results of Experiment 2 not only verify that the centroid of a set of multiple items can serve as the focus of ensemble-based attention, but they also suggest that the centroids of ensembles can be extracted in a compulsive, obligatory manner to direct the deployment of attention, as are other ensemble feature of visual textures (Allik, Toom, Raidvee, Averin, & Kreegipuu, 2014;Oriet & Brand, 2013).…”

Ensemble representation and the contents of visual experience

“…Although it was once suggested that sampling strategies of this kind might explain the performance of subjects in ensemble perception studies (e.g. Allik et al 2013Allik et al , 2014Marchant et al 2013), that view is now regarded as having been conclusively rebutted, for ensemble judgements are simply too accurate to be explained in terms of limited samples Utochkin and Tiurina 2014;Haberman and Whitney 2012;Brady and Alvarez 2015;Albrecht et al 2012).…”