July 22, 2008
For Immediate Release
Contact: Catherine West
How carrots help us see the color orange
of the easiest ways to identify an object is by its color -- perhaps it
is because children’s books encourage us to pair certain objects with
their respective colors. Why else would so many of us automatically
assume carrots are orange, grass is green and apples are red?
two experiments by Holger Mitterer and Jan Peter de Ruiter from the Max
Planck Institute for Psycholinguistics, perception of color and color
constancy (the ability to see the same color under varying light
conditions) were examined using different hues of orange and yellow. By
using these hues on different objects, the researchers hoped to show
that knowledge of objects can be used to identify color.
one experiment, half of the participants saw traditionally-colored
orange objects in their respective hue, while the other participants
saw the same objects in an ambiguous hue between yellow and orange. The
participants that saw the ambiguous hue on traditionally-colored orange
objects later called the item with that ambiguous hue "orange".
Apparently, seeing the ambiguous hue on a traditionally-colored orange
objects led participants to redefine that hue to be proper "orange".
the second experiment, participants saw the same hues, but now on
objects that could be any color (e.g., a car). Some participants were
shown objects that ranged from the ambiguous color from the first
experiment to a strong yellow hue, while others were shown objects in a
range of strong orange hues to the ambiguous color. Just as in the
first experiment, participants then had to identify a sock that had
been colored with an ambiguous hue. This second experiment revealed no
differences between the two groups, showing conclusively that it was
only the knowledge of how objects are naturally colored that made them
redefine the colors in the first experiment.
The results, published in the July issue of
a journal of the Association for Psychological Science, determined that
the use of top-down processing, such as a carrot signifying the color
orange, is delayed in both color perception and also in other
perceptual domains. If humans used this conceptual knowledge
immediately, it would override perceptual cues and cause
“Delayed feedback for learning prevents
such illusions, but still utilizes prior probabilities provided by
world knowledge to achieve perceptual constancy,” the researchers
Author Contact: Holger Mitterer [email protected]
is ranked among the top 10 general psychology journals for impact by
the Institute for Scientific Information. For a copy of the article
“Recalibrating Color Categories Using World Knowledge” and access to
Psychological Science research findings, please contact Catherine West at 202-293-9300 or [email protected].