Long-term chromatic adaptation is a rarely studied and, thus, poorly understood phenomenon. That this phenomenon exists and has a profound effect on the red-green chromatic mechanism has been posited for several decades. The research presented here examined this type of adaptation in relation to equilibrium percepts. These percepts represent balance points in visual mechanisms. Any shifts from equilibria should give insight into the neural processes of long-term chromatic adaptation.
The research builds on the work of Neitz et al. (2002) who demonstrated a shift in a unique hue after intermittent daily exposure to a long-wavelength light over several days or weeks. The research had two principal goals. The first was to measure shifts in the equilibrium percepts of the two color-opponent mechanisms to determine if such shifts can be explained solely by a linear transformation of cone sensitivities. Shifts in the unique hues which have a spectral locus were measured. In addition, shifts in unique yellow only were measured when long-term-chromatic adaptation was combined with short-term chromatic adaptation. The latter is a well-modeled neural process. The goal of the combined adaptation experiment was to determine if the two adaptational mechanisms are independent. In addition, a third set of measurements were made to determine if combined equilibria in the two color-opponent mechanisms (i.e., red/green and yellow/blue) produce an achromatic percept under long-term chromatic adaptation. A fourth experiment investigated whether long-term chromatic adaptation affected the luminance (i.e., non-chromatic) mechanism.
The second goal was to test a new long-term chromatic adaptation methodology. Previously reported work used a several-hour exposure to a reddish chromatic environment. The new methodology used a one-hour exposure to a changing CRT pattern composed mainly or R phosphor.
|Advisor:||Shevell, Steven K.|
|School:||The University of Chicago|
|School Location:||United States -- Illinois|
|Source:||DAI-B 69/11, Dissertation Abstracts International|
|Keywords:||Chromatic adaptation, Color vision, Equilibrium percepts|
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