handout (pdf 500K)
Purpose. To explore the differences and similarities in light adaptation results from the probed-sinewave paradigm over the past 40 years from Boynton, Sturr, and Ikeda (1961, JOSA, 51, 196-201), Shickman (1970, JOSA, 60, 107-117), Maruyama and Takahashi (1977, Tohoku Psychologica Folia, 36, 120-133), Hood, Graham, von Wiegand, and Chase (1997, Vis Res, 37, 1177-1191), Wu, Burns, Elsner, Eskew, and He (1997, JOSA, 14, 2367-2378), Shady (1999, PhD Dissertation, Columbia University), Demarco, Hughes, and Purkiss (2000, Vis Res, 40, 1907-1919), Snippe, Poot, and van Hateren (2000, Vis Neurosci, 17, 449-462), and Wolfson and Graham (Vis Res, in press).
Methods. In the probed-sinewave paradigm, detection threshold is measured for a test probe superimposed at various phases on a sinusoidally flickering background. The studies were conducted under widely varying conditions.
Results. In all the datasets the dc-level (threshold averaged over all phases) increases dramatically as the frequency of the flickering background increases and then drops as the frequency continues to increase; the peak occurs between about 8 and 20 Hz. The shape of the curves collected at low frequencies (approx 2 Hz) is quite similar in all the studies, showing a distinct drop in threshold at the phase when the intensity of the flickering background is lowest. The shape of the curves collected at middle frequencies (approx 10 Hz) is not consistent across studies, but fall into at least two groups. The shape of the curves collected at high frequencies (approx 30 Hz) is quite similar in the few studies measuring that high.
Conclusions. Despite drastic changes in the stimulus parameters (e.g., mean luminance of 31 to 7500 tds, probe size of 46 arcmin to 2 degrees, etc) probed-sinewave results from different studies are quite similar at low frequencies and also at high frequencies of the modulating background; the results are not as stable at middle frequencies (approx 10 Hz).