Motion defined exclusively by second-order characteristics does not evoke optokinetic nystagmus.
We showed high-contrast, second-order motion stimuli to subjects whilst recording their horizontal eye movements. These stimuli were very poor at evoking optokinetic nystagmus. Smooth-pursuit eye movements and fixation were reduced by a masking band +/- 2.5 deg above and below an imaginary fixation point. First-order stimuli evoked vigorous optokinetic nystagmus (OKN) under identical conditions and also when matched for apparent contrast. These findings are discussed in terms of the site of detection of second-order motion.
Harris
L R
LR
Department of Psychology, York University, Toronto, Ontario, Canada.
Smith
A T
AT
D000328:Adult; D005133:Eye Movements / Q000502:physiology; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology