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Color vision and the real world |
Most of what we know about color perception has been established with near threshold paradigms. That is, colors that are used to investigate human color perception are often very faint lights that are just barely perceptible. For example, people may be asked to make “just noticeable difference” judgments about the color difference between two lights. Although we have learned quite a lot about human color perception using these techniques, near threshold conditions are not ecologically valid as they do not represent the world we live in: a world full of often vivid colors that are part of complex scenes. The scientific question, therefore, is whether the same principles, laws, and theories that were developed with near threshold paradigms apply to the perception of colors in more naturalistic scenes. The short answer is that they don’t. The difficult and tedious scientific task is therefore to extend our knowledge of color vision to these more complex conditions.
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| Visual search
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Visual search is a common task, which involves searching for a target element presented among a number of distractor elements (think of looking for your car, the target, among a large number of “distractor” cars in a parking lot). Visual search is a nice paradigm because it has multiple ecologically valid characteristics: the processing of multiple visual elements is investigated, supra-threshold colors (saturated colors) can be used, and visual attention is inherently part of the task. In a series of paper Allen Nagy and myself looked at the nature and number of the chromatic mechanisms mediating search for colored targets (Monnier & Nagy, 2001a, 2001b). More recently, I have looked at multidimensional targets (elements that differed from distractors along 2 dimensions) were detected my neural mechanisms tuned to both dimensions (Monnier, 2006). Right now in the lab, our current efforts are aimed at determining the bandwidth of the chromatic mechanisms mediating search. This is a brand new project and I will post more information as we make progress in this new project. Check again soon!
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