The peripheral flicker effect: Desensitization of the luminance pathway by static and modulated light

Abstract

Previous studies have shown that luminance flicker, presented peripheral to a foveal test target, increases thresholds for target detection: the peripheral flicker (PF) effect. These studies have also shown that thresholds are elevated more for luminance targets, relative to chromatic targets. In the present study we examined the specificity of the PF effect on the luminance mechanism and assessed the contribution of modulated stray-light to the test field, as well as longer range spatial interactions. We found that the presence of a foveal luminance pedestal, as well as PF, caused a notch to appear in the spectral sensitivity function around 570 nm. This result confirms the hypothesis that the PF effect decreases the sensitivity of the luminance pathway. To assess the contribution of stray-light to the PF effect, we modulated a luminance pedestal without the presence of PF in order to simulate the stray-light effect in isolation. A decrease in sensitivity for wavelengths around 570 nm occurred with modulated stray-light, suggesting that modulated stray-light contributes substantially to this effect. We then minimized the modulated stray-light by phase-reversing a checkerboard pattern in the periphery. A significant, though smaller, threshold elevation to mid-spectrum stimuli was obtained, suggesting that long range spatial effects are also active in the PF effect. We conclude that the PF effect causes a desensitization of foveal luminance pathways via local and more long range spatial interactions. Our results are consistent with previous data which suggest that the PF effect is due to selective adaptation of cells in the magnocellular pathway (M-cells). Our data imply that local network adaptation may be a property of the magnocellular pathway.

Sensory adaptation as Kalman filtering: theory and illustration with contrast adaptation

“…These mechanisms include bipolar-cell processes (Brown andMasland 2001, Rieke 2001), ganglion-cell processes (Kim and Rieke 2001) and different processes for the on and off pathways (Chander and Chichilnisky 2001, Kim and Rieke 2001, Rieke 2001. Finally, it is important to point out that these adaptation mechanisms appear to be present in the human retina (Heinrich and Bach 2001) and to have perceptual correlates (Anstis 1996, DeMarco et al 1997, Freeman and Badcock 1999.…”

Flash masking and facilitation by nearby luminance perturbations

“…Thus the approach may be viewed as distinct from, though logically similar to, peripheral effect studies. 5 In the latter no attempt is made to introduce sensitivity-changing peripheral stimuli to the same mechanism as is devoted to coding the target. The measured effects of these noise probes that we employ allow us to reject a number of rather simple schemes by which signals in the receptive field are summed.…”