Temporal integration and contrast sensitivity in foveal and peripheral vision

Spatial contrast sensitivity functions and temporal integration functions for gratings with dark surrounds were measured at various eccentricities in photopic vision. Contrast sensitivity decreased with increasing eccentricity at all exposure durations and spatial frequencies tested. The decrease was faster at high than at low spatial frequencies, but similar at different exposure durations. When cortically similar stimulus conditions were produced at different eccentricities by M-scaling, contrast sensitivity became independent of visual field location at all exposure durations tested. The results support the view that in photopic vision spatiotemporal information processing is qualitatively similar across the visual field, and that quantitative differences result from retino-topical differences in ganglion cell sampling. For gratings of constant retinal area temporal integration (improvement of contrast sensitivity with increasing exposure duration) was more extensive at high than at low retinal spatial frequencies but independent of cortical spatial frequency and eccentricity. For M-scaled gratings temporal integration was more extensive at high than at low cortical spatial frequencies but independent of retinal spatial frequency and eccentricity. The results suggest that the primary determinant of temporal integration is not spatial frequency but grating value that is calculated as AF2 square cycles (cycle2), where A is grating area and F spatial frequency.     

Comments on a standardized version of Luria's tests

Appreciation is expressed for the work of Golden's group in the selection of Luria's tests, the standardization of their administration, the collection of norms, and the evaluation of the reliability and validity of the Luria-Nebraska test battery. However, questions are raised concerning the ability of the test to efficiently handle topical diagnosis and to construct rehabilitation programs. Concern is expressed over the possible vulgarization of Luria's doctrine of functional systems and the loss of predictive power in Luria's tests through neglect of qualitative information and methodology. Suggestions are made as to how Luria's qualitative methodology might be incorporated in a standardized version of a neuropsychological examination.