Disappearance elicited by contrast decrements.

Area of Science:

• Visual perception
• Neuroscience
• Psychophysics

Background:

• Visual stimuli can disappear from consciousness, a phenomenon studied for centuries.
• Known causes include stationary peripheral images (Troxler effect) and contrast increment masking.
• Both require image stabilization on the retina.

Purpose of the Study:

• To describe a novel phenomenon causing visual stimuli to disappear from conscious awareness.
• To investigate the characteristics of disappearance induced by contrast decrements (CDs).
• To compare CD-induced disappearance with existing phenomena like the Troxler effect and masking.

Main Methods:

• Four experiments were conducted to examine the characteristics of CD-induced visual disappearance.
• Stimuli were nearly stabilized images in the visual periphery.
• Contrast decrements were induced by changes in target or background luminance.

Main Results:

• Contrast decrements (CDs) can cause nearly stabilized peripheral images to disappear instantaneously from awareness.
• This disappearance occurs without significant adaptation periods and lacks after-images.
• Loss of sensitivity to stimuli was immediate, lasting approximately 2 seconds, and increased with eccentricity.

Conclusions:

• Contrast decrements represent a third distinct mechanism for removing visual stimuli from conscious awareness.
• CD-induced disappearance is rapid and differs from Troxler effect adaptation and masking.
• The phenomenon's characteristics, including duration and frequency, were elucidated, offering new insights into visual perception.