title: Ensemble perception in autism spectrum disorder: Member-identification versus mean-discrimination.
abstract: To efficiently represent the outside world our brain compresses sets of similar items into a summarized representation, a phenomenon known as ensemble perception. While most studies on ensemble perception investigate this perceptual mechanism in typically developing (TD) adults, more recently, researchers studying perceptual organization in individuals with autism spectrum disorder (ASD) have turned their attention toward ensemble perception. The current study is the first to investigate the use of ensemble perception for size in children with and without ASD (N = 42, 8-16 years). We administered a pair of tasks pioneered by Ariely [2001] evaluating both member-identification and mean-discrimination. In addition, we varied the distribution types of our sets to allow a more detailed evaluation of task performance. Results show that, overall, both groups performed similarly in the member-identification task, a test of "local perception," and similarly in the mean identification task, a test of "gist perception." However, in both tasks performance of the TD group was affected more strongly by the degree of stimulus variability in the set, than performance of the ASD group. These findings indicate that both TD children and children with ASD use ensemble statistics to represent a set of similar items, illustrating the fundamental nature of ensemble coding in visual perception. Differences in sensitivity to stimulus variability between both groups are discussed in relation to recent theories of information processing in ASD (e.g., increased sampling, decreased priors, increased precision). Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1291-1299. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
authors.affiliation: Laboratory of Experimental Psychology, Brain and cognition, KU Leuven, Leuven, Belgium.|Department of Child Psychiatry, UPC-KU Leuven, Belgium.|Leuven Autism Research (LAuRes), KU Leuven, Leuven, Belgium.
authors.forename: Ruth
authors.identifier: http://orcid.org/0000-0001-6899-4898
authors.initials: R
authors.lastname: Van der Hallen
authors.affiliation: Laboratory of Experimental Psychology, Brain and cognition, KU Leuven, Leuven, Belgium.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lemmens
authors.affiliation: Department of Child Psychiatry, UPC-KU Leuven, Belgium.|Leuven Autism Research (LAuRes), KU Leuven, Leuven, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Steyaert
authors.affiliation: Leuven Autism Research (LAuRes), KU Leuven, Leuven, Belgium.|Parenting and Special Education Research Unit, KU Leuven, Leuven, Belgium.
authors.forename: Ilse
authors.initials: I
authors.lastname: Noens
authors.affiliation: Laboratory of Experimental Psychology, Brain and cognition, KU Leuven, Leuven, Belgium.|Leuven Autism Research (LAuRes), KU Leuven, Leuven, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Wagemans
mesh_terms: D000293:Adolescent; D000067877:Autism Spectrum Disorder / Q000503:physiopathology*; D002648:Child; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D013647:Task Performance and Analysis; D014796:Visual Perception / Q000502:physiology*
keywords: autism spectrum disorder; ensemble encoding; local-global; visual perception