Exploring Visual Adaptation at High Intensity Levels Using a Pulse-Probe Paradigm
Interim rept. Jul 2005-Jun 2006
NORTHROP GRUMMAN CORP SAN ANTONIO TX INFORMATION TECHNOLOGY
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This report describes four experiments in which the temporal changes in visual adaptation that occur during exposure to a train of brief, high intensity discrete light pulses over 8 log trolands were explored using a pulse-probe paradigm. For this, the threshold for detecting a probe light stimulus was measured at various latencies with respect to a discretely modulated pulse background. Experiments I and II used a 10 ms probe, and explored forward and backward masking for repetitive pulse trains 3 Hz and 10 Hz and for single pulses. Experiments III and IV also used 3 Hz and 10 Hz pulse trains, but varied the duration of the probe stimulus. The results indicate that asymmetries in the dynamics of forward and backward masking are evident at high intensity levels, that pulse trains induce a DC shift in light adaptation mechanisms, and that stimuli presented during the backward masking window can still contribute to the detection process.
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