title: The continuum of detection and awareness of visual stimuli within the blindfield: from blindsight to the sighted-sight.
abstract: OBJECTIVE
  We investigated systematically the effect of repeated exposure on detection and reported awareness of visual stimuli presented deep within the field defect of 5 hemianopic patients.
  
  
  METHODS
  An objective measure of sensitivity (detection in a temporal two-alternative forced-choice paradigm) and subjective reports of awareness were recorded on trial by trial bases. Visual stimulus to be detected was a temporally modulated (10 Hz) circular patch (6° diameter) of vertical grating (1 c/°). Hemianopic patients took part in the study 8 to 15 months after injury, so that the findings could not be attributed to spontaneous recovery.
  
  
  RESULTS
  Initially, high contrast (90%) target stimuli were detected at or near chance level with little reported awareness. In 4 of 5 cases, repeated stimulation led to improved sensitivity, indicated by increased detection scores and higher incidence of awareness. In a fifth case, there was no change in sensitivity despite extensive exposure (>22,000 trials).
  
  
  CONCLUSIONS
  At retinal locations deep within the field defect, repeated stimulation can lead to blindsight performance (type I detection without awareness), followed by detection with reported awareness (type II blindsight), and eventual reported visual experiences. The findings indicate that conscious awareness of stimuli lies on a continuous spectrum and repeated systematic training can lead to improved visual sensitivity.
authors: Vision and Attention Laboratories, School of Psychology, College of Life Sciences and Medicine, King's College, University of Aberdeen, Aberdeen, United Kingdom. a.sahraie@abdn.ac.uk
authors: Arash
authors: A
authors: Sahraie
authors: Ceri T
authors: CT
authors: Trevethan
authors: Mary-Joan
authors: MJ
authors: Macleod
authors: Lawrence
authors: L
authors: Weiskrantz
authors: Amelia R
authors: AR
authors: Hunt
mesh_terms: D000328:Adult; D001364:Awareness / Q000502:physiology*; D001766:Blindness / Q000503:physiopathology* / Q000534:rehabilitation*; D005260:Female; D006423:Hemianopsia / Q000503:physiopathology* / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D020521:Stroke / Q000503:physiopathology; D014793:Visual Cortex / Q000502:physiology / Q000503:physiopathology; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
keywords: blindsight; hemianopia; rehabilitation