Local motion processing limits fine direction discrimination in the periphery.
Visual sensitivity is reduced in the periphery for many discrimination tasks. Previously it has been reported that motion coherence thresholds are higher for dot stimuli presented in the periphery, a finding that could arise either from (a) impaired motion integration or (b) from motion integrators inheriting more noisy local directional signals. We sought to disentangle these factors using an equivalent noise paradigm. We report a deterioration in discrimination thresholds in the periphery that does not result from reduced visibility and is fully accounted for by an increase in local directional uncertainty with no change in sampling efficiency. Changes in motion coherence thresholds with stimulus eccentricity, measured using similar stimuli, exhibit a high degree of inter-subject variability.
UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK; Department of Optometry and Visual Science, City University, Northhampton Square, London EC1V 0HB, UK.
Isabelle
I
Mareschal
UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK; Schepens Eye Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.
Peter J
PJ
Bex
UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK.
Steven C
SC
Dakin
D015350:Contrast Sensitivity / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000295:instrumentation / Q000379:methods; D011594:Psychometrics; D011601:Psychophysics; D012684:Sensory Thresholds / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*