Decoding the True Perception of Small Green Spots: Investigating Veridical Visual Experience

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The following is a summary of “It’s not easy seeing green: The veridical perception of small spots,” published in the May 2023 issue of Opthalmology by Vanston, et al.

For a study, researchers sought to investigate the factors that influence color appearance when stimulating single cones with the light of a specific spectral composition. For example, when presented with spots of 543 nm light against a white background, subjects reported varying percepts of predominantly red, white, and green. However, when the same light was viewed over a large field under normal viewing conditions, it consistently appeared green and highly saturated. The study aimed to determine which stimulus parameters are crucial in transitioning between these two perceptual extremes.

Researchers used an adaptive optics scanning laser ophthalmoscope to vary the stimuli’s size, intensity, and retinal motion. The stimuli were either stabilized in specific locations or allowed to drift across the retina along with the eye’s natural motion. The results showed that increasing the stimuli’s size and intensity increased the likelihood of perceiving monochromatic spots of light as green. Higher intensities also led to increased perceived saturation. Interestingly, there was an interaction between size and intensity, suggesting that the balance between magnocellular and parvocellular activation may be critical for color perception.

Surprisingly, the study found that color appearance did not depend on whether the stimuli were stabilized or allowed to drift. This suggests that the sequential activation of many cones is less effective in driving hue and saturation perception than the simultaneous activation of many cones.

In conclusion, the study highlighted the importance of stimulus size and intensity in determining color appearance when stimulating single cones. 

The balance between magnocellular and parvocellular activation plays a crucial role. Furthermore, simultaneous activation of multiple cones seems to be more influential in color perception than sequential activation.


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