Motion processing in peripheral vision: reaction time and perceived velocity.

Reaction times to motion onset were measured as a function of eccentricity of presentation. These were compared with measurements of perceived speed at various eccentricities. For slowly moving targets, both dependent measures changed substantially with eccentricity: RT increased and perceived speed declined. For more rapidly moving targets, both dependent measures were unchanged by eccentricity. These results may be related to the difference between retinotopic distribution of neural mechanisms responsive to low rates of temporal modulation and the retinotopic distribution of neural mechanisms responsive to higher rates of temporal modulation.