Effects of visual short-term memory load and attentional demand on the contrast response function

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Memory Research

Background:

• Visual short-term memory (VSTM) load is known to impair ongoing perception.
• The precise mechanism underlying this VSTM load effect on perception remains debated, with possibilities including contrast gain or response gain modulation.
• The role of attentional resources in mediating VSTM load effects on perception is not fully understood.

Purpose of the Study:

• To determine if VSTM load impacts perception via contrast threshold or asymptote changes.
• To investigate whether attentional resource availability modulates VSTM load effects on the contrast response function.
• To explore the interplay between attention, VSTM, and visual perception.

Main Methods:

• Manipulated VSTM load using a color and location VSTM task with varying memory set sizes.
• Assessed the contrast response function for orientation discrimination during VSTM maintenance.
• Varied attentional demand using spatial cuing of the orientation stimulus.

Main Results:

• Increased VSTM load elevated the contrast threshold of the contrast response function.
• This effect on the contrast threshold was contingent on attentional demand; it was eliminated when attention demand was reduced via cuing.
• VSTM load did not affect the asymptote of the contrast response function, ruling out response gain accounts.

Conclusions:

• VSTM load impairs perceptual sensitivity by increasing contrast thresholds, indicating a contrast gain modulation mechanism.
• This VSTM-induced perceptual impairment occurs only when the perceptual task requires attentional resources.
• Findings support the hypothesis that attentional resources are shared between perception and VSTM maintenance.