The effects of age on the spatial and temporal integration of global motion.

The purpose of this study was to determine the relative contributions of local element speed and/or spatial displacement to age-related deficits in global motion processing. Motion coherence thresholds (79% correct) were measured for discriminating the direction of translational random dot kinematograms (RDKs) as a function of dot speed and spatial displacement across the adult lifespan (20-79 years). Age-related impairments in global motion processing were only apparent in observers 70-79 years of age. In agreement with previous studies, we found an age-related impairment at low (0.625 deg/s) and high speeds (10 deg/s). However, these effects were heavily mediated by dot spatial displacement. Motion coherence thresholds were also most markedly elevated in women aged over 70 years. These findings suggest a prominent role of spatial integration in global motion processing. Moreover, global motion perception appears to be relatively well preserved until around 70 years of age.