An explicit investigation of the roles that feature distributions play in rapid visual categorization

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Hee Yeon Im - , Harvard University (Author)
  • Natalia A. Tiurina - , Higher School of Economics (Author)
  • Igor S. Utochkin - , Higher School of Economics (Author)

Abstract

Ensemble representations are often described as efficient tools when summarizing features of multiple similar objects as a group. However, it can sometimes be more useful not to compute a single summary description for all of the objects if they are substantially different, for example when they belong to entirely different categories. It was proposed that the visual system can efficiently use the distributional information of ensembles to decide whether simultaneously displayed items belong to single or several different categories. Here we directly tested how the feature distribution of items in a visual array affects an ability to discriminate individual items (Experiment 1) and sets (Experiments 2–3) when participants were instructed explicitly to categorize individual objects based on the median of size distribution. We varied the width (narrow or fat) as well as the shape (smooth or two-peaked) of distributions in order to manipulate the ease of ensemble extraction from the items. We found that observers unintentionally relied on the grand mean as a natural categorical boundary and that their categorization accuracy increased as a function of the size differences among individual items and a function of their separation from the grand mean. For ensembles drawn from two-peaked size distributions, participants showed better categorization performance. They were more accurate at judging within-category ensemble properties in other dimensions (centroid and orientation) and less biased by superset statistics. This finding corroborates the idea that the two-peaked feature distributions support the “segmentability” of spatially intermixed sets of objects. Our results emphasize important roles of ensemble statistics (mean, range, distribution shape) in explicit visual categorization.

Details

Original languageEnglish
Pages (from-to)1050-1069
Number of pages20
JournalAttention, Perception, and Psychophysics
Volume83
Issue number3
Publication statusPublished - Apr 2021
Peer-reviewedYes
Externally publishedYes

External IDs

PubMed 32410015
ORCID /0000-0002-1631-4042/work/142255428

Keywords

Keywords

  • Categorization, Centroid, Ensemble statistics, Mean orientation, Mean size, Segmentation

Library keywords