Central and Off-Axis Spatial Contrast Sensitivity Measured With Gabor Patches

Report No. ARL-TR-5363
Authors: William A. Monaco, O.D., Ph.D.; Kent E. Higgins, Ph.D.; Joel T. Kalb, Ph.D.
Date/Pages: September 2010; 20 pages
Abstract: The U.S. Army acquisition community uses models of human and systems performance to evaluate materiel. One such model, used to assess equipment for the dismounted Soldier, is the Individual Warrior Simulation (IWARS). When Soldier modeling target acquisition, IWARS applies the ACQUIRE model to some portion of the visual scene, determines the probability of detecting a target if one is present, then repeats the process for a different portion of the field. ACQUIRE predicts the probability of visually acquiring a target presented anywhere within its field of view (FOV) without regard for the location of the target in the scene. Human visual performance varies dramatically across the FOV, with acuity decreasing rapidly as objects move away from the center of gaze or away from the central vertical and horizontal axes of vision. The current research used Gabor patches to characterize visual detection thresholds at various locations around central vision. Results showed a marked increase in contrast threshold for targets of a y of spatial frequencies ranging from 0.5 to 18.2 cycles/degree appearing greater than ±3¿-4¿ horizontal eccentricity. These results can be used to intelligently constrain the portion of the visual field over which IWARS applies the ACQUIRE detection model.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2010