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Absolute and relative blindsight.

Tarryn Balsdon1, Paul Azzopardi1

  • 1Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK.

Consciousness and Cognition
|October 13, 2014
PubMed
Summary
This summary is machine-generated.

Relative and absolute blindsight in normal observers may stem from response bias, not distinct neural processes. Using bias-free measures abolished these effects, suggesting they are artifacts of assessment methods.

Keywords:
BlindsightConfidence ratingsConscious awarenessLow visionMetaconstrast maskingSignal detectionType 2 blindsight

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Area of Science:

  • Cognitive Neuroscience
  • Psychology
  • Neuroscience

Background:

  • Relative blindsight, a difference in conscious awareness despite matched performance, was proposed to find neural correlates of consciousness (NCC).
  • Absolute blindsight describes a performance-awareness discrepancy irrespective of performance matching.
  • Investigating these phenomena in normal observers is crucial for understanding consciousness.

Purpose of the Study:

  • To determine if response bias can explain relative and absolute blindsight in normal observers.
  • To re-evaluate the methodology used in previous blindsight studies.
  • To clarify the nature of blindsight phenomena and their NCC implications.

Main Methods:

  • Replication of Lau and Passingham's (2006) experiment.
  • Utilizing a bias-free two-alternative forced-choice (2AFC) task to assess performance.
  • Employing signal detection theory (SDT) with confidence ratings for bias-free awareness assessment.

Main Results:

  • The relative blindsight effect disappeared when using a bias-free 2AFC task.
  • Varying the criterion for awareness also eliminated the relative blindsight effect.
  • No evidence for relative or absolute blindsight was found when using bias-free SDT measures.

Conclusions:

  • Relative and absolute blindsight in normal observers appear to be artifacts of response bias in performance and awareness assessments.
  • The findings challenge the interpretation of blindsight as a direct indicator of NCC.
  • Understanding psychometric function properties is key to distinguishing different types of blindsight and avoiding trivial interpretations.