Inattentional noise leads to subjective color uniformity across the visual field

Humans perceive a vividly colored world coherently across the visual field, even though our peripheral vision has limited color sensitivity compared to central vision. How is this sense of color uniformity achieved? This question can be explored through a phenomenon called the pan-field color illusion, in which observers perceive scene images achromatized in the peripheral region (chimera images) as full-color images. Our previous work demonstrated that inattention to the peripheral visual field contributed to this illusion. Upon this observation, the current study presents signal detection theory modeling to quantify the effects of inattention on internal color signal strength and its variability. The model fitting has revealed that inattention to the peripheral region increases internal signal variability. This inattentional noise increases the occurrence of strong color signals that exceed the internal color detection criterion, thereby intensifying the pan-field color illusion. These results extend previously documented effects of inattentional noise on simple psychophysical tasks (e.g., "subjective inflation" in grating detection and discrimination), accounting for the illusorily enriched peripheral color experience for naturalistic scene images. Our findings suggest that inattentional noise inherent in peripheral vision would be a key factor in achieving the vivid visual phenomenology experienced across the entire visual field.