Final answer:
The idea of a retinal image not unambiguously specifying a stimulus is related to color constancy.
Step-by-step explanation:
The idea that a particular image on the retina could have been caused by an infinite number of different objects is related to the concept of color constancy.
Color constancy is the ability of our visual system to perceive the color of an object as relatively constant, even under different lighting conditions. Our brain can take into account the surrounding context and make adjustments to perceive the object's color as it truly is.
This phenomenon is due to the signal processing that occurs in our eyes before the information is sent to the brain, where comparisons between adjacent light receptors and sensitivity to edges help us perceive the true color of an object.