reprint (pdf 500K)
Using the probed-sinewave paradigm, we explore the differences between increment and decrement probes across a range of frequencies (approx. 1-19 Hz). In this paradigm, detection threshold is measured for a small test probe presented on a large sinusoidally flickering background (at eight different phases). Probe thresholds are very similar for increments and decrement probes, but there is a small and systematic difference: increment thresholds are usually slightly higher relative to decrement thresholds during the part of the background cycle when the background intensity is increasing. The results are compared to current models of light adaptation.
Supported by NIH grants EY08459 to Norma Graham and EY06933 to Sabina Wolfson.