Poster Session I: Effect of flicker adaptation on perception of small spots presented with AOSLO.

Abstract

Previous work suggests the detection of small spots is mediated by a mixture of chromatic and achromatic mechanisms. We tested whether exposure to spatially-uniform chromatic or luminance flicker affected detection thresholds for 543 nm increments delivered through an AOSLO. Heterochromatic flicker photometry was used to determine isoluminant settings for the red and green primaries of a DLP display; this isoluminant red-green mixture provided the 2.1° background upon which 23 arcmin (N=4) or 3 arcmin (N=2) stimuli were presented for 100ms. The projector background was modulated to produce isoluminant chromatic flicker or isochromatic luminance flicker at 3.75 or 30 Hz. The time-averaged luminance and chromaticity for all adaptation conditions were equivalent. For each condition, data collection was preceded by 2 minutes of preadaptation, followed by alternating windows of stimulus delivery (1 sec, steady background) and top-up adaptation (3 sec). Thresholds for all flicker conditions were compared to data obtained on a static background. For 23 arcmin spots, we found reduced sensitivity in the 3.75 Hz chromatic and luminance flicker conditions, but no adaptation effect was observed for 3 arcmin flashes or for 30 Hz flicker of either type. Our data suggest that raster-scanned, AO-corrected stimuli are susceptible to flicker adaptation, but that proximity to a flickering edge may be an important factor governing the effects of contrast adaptation on small spot detection.