Thresholds are determined at various short times before and after the onset of a 38-mL conditioning stimulus in the dark-adapted eye, and following six other levels of pre-adaptation. An outstanding feature of the results is that under certain conditions thresholds decrease with increasing pre-adapting luminance. The results are considered to provide an indirect picture of on-responses in the visual system. The relation between “masking” associated with these on-responses and those effects attributable to photochemical bleaching is assessed and discussed.
ROBERT M. BOYNTON and GILLRAY KANDEL, "On Responses in the Human Visual System as a Function of Adaptation Level," J. Opt. Soc. Am. 47, 275-286 (1957)