Color – Binding, Color Memory, Synesthesia & Aesthetics

Binding
If the brain processes form, color and motion information in parallel “Where” and “What” tracks, than what binds the information together so that you have a coherent experience of the world, so that you see the moving yellow tennis ball as one entity? This is a philosophical as well as an empirical problem. Some have suggested that binding is just an illusion brought about by the relatively close timing of the activation of the different parallel tracks. Others have suggested that the feedback circuits and cross-talk between higher brain regions, perhaps through poorly defined mechanisms involving brain “oscillations”, are critical to binding. What remains clear is that there is a lot unknown about how visual signals are integrated to bring about perception; defining the problems is the first challenge.

Color Memory
Thorsten Hansen and his colleagues in Giessen Germany have found that when asked to remove the color from a digital photograph of a familiar object, people tend to overcompensate, adding more of the opposing color than was necessary to render the image colorless. For example, people asked to remove the color of a banana will tend to make the banana bluish; they say the banana looks achromatic. It is as if the subjects are trying to remove some of the memory color associated with the form of the object.

Synesthesia
Synesthesia is a neurobiological condition in which the stimulation of one sensory system activates a different sensory experience. Many forms of synesthesia have been identified. A common form is the experience of numbers having an associated color experience. In other cases music is accompanied by color experience. Others cross-wire the somatosensory system and taste. These conditions appear to be more extreme than the common practice of making cross-sensory metaphors—such as, ‘sharp cheese’ or ‘loud sweater.’

The neural basis for synesthesia is unknown, although laboratory models developed in Mirganka Sur’s lab at MIT are being developed. In these models, the optic nerve signals are genetically engineered to go to the primary auditory cortex. These animals then “hear” visual signals. Other research involves careful testing of people who claim to be synesthetes. Many synesthetes use their synesthesia in their creative endeavors, such as photographer Marcia Similack, who visited the Vision and Art class in the Spring to discuss life as a synesthetic artist.

Aesthetics
Aesthetics is the philosophical study of sensory-emotional values. It concerns how we judge art, what we decide is “great” art and what is “kitsch”. There is a growing group of neuroscientists who are interested in determining the neural basis for aesthetics. Two leaders of this new field of “neuroaesthetics” are Semir Zeki and VS Ramachandran. Although perhaps related, the field of Vision and Art has less grand aspirations, and aims to uncover mechanistic explanations for why certain artistic strategies are effective in terms of visual information processing. Margaret Livingstone, Patrick Cavanagh, Christopher Tyler and Bevil Conway, among many others, have done work in this field.