title: Spatial localisation in autism: evidence for differences in early cortical visual processing.
abstract: BACKGROUND
  Vision in people with autism spectrum conditions (ASC) is reported to be different from people without ASC, but the neural level at which the differences begin to occur is not yet known. Here we examine two variants of a vernier acuity task to determine if differences are evident in early visual processing.
  
  
  RESULTS
  Abutting and separated vernier acuity was assessed in 16 people with ASC and 14 matched controls. In controls, abutting and separated thresholds were unrelated (r = 0.13, p = 0.65), suggesting thresholds are determined by two separate mechanisms. In contrast, the abutting and separated thresholds of ASC observers were strongly correlated (r = 0.88, p < 0.0001), with separated thresholds tending towards being superior to those of controls [t(28) = -2.46, p = 0.02].
  
  
  CONCLUSIONS
  The findings suggest the mechanisms employed by ASC observers in separated vernier tasks are different to those of controls. This psychophysical evidence suggests that visual differences in ASC may begin at an early cortical stage of visual processing.
authors: Department of Vision & Hearing Sciences, Anglia Ruskin University, Cambridge, UK. keziah.latham@anglia.ac.uk.
authors: Keziah
authors: K
authors: Latham
authors: Susana Tl
authors: ST
authors: Chung
authors: Peter M
authors: PM
authors: Allen
authors: Teresa
authors: T
authors: Tavassoli
authors: Simon
authors: S
authors: Baron-Cohen