Our Brains Fill In The Colors Of Black And White Photos: Is The World A Giant Coloring Book?
German study finds the brain registers colors even when they aren’t there, which may explain why some people have hallucinations.
The birth of the color camera dates to the late 1800s, and yet black and white film prevails as a mainstay in contemporary art. Black and white was commonplace in cinema through the 1960s, even though the price and difficulty of using color had dropped significantly. Every few years, movies like The Artist and Frances Ha remind Hollywood and film lovers of the inherent value of black and white.
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One key to this success is, despite lacking color, B&W remains visually stimulating, and new research from the University of Tübingen, Germany may explain why and offer a possible explanation for hallucinations.
Eighteen volunteers were shown B&W photos of real-life objects that are typically associated with a single color (bananas with yellow, broccoli with green, strawberries with red, etc.). While they viewed these images, the team recorded the subjects' brain activity by fMRI.
To disguise the true intentions of the experiment, the objects on the screen were slowly rotated, and the participants were asked to report the direction of the motion. This distraction was meant to keep them from automatically registering the color of the object, according to the authors.
Next the scientists displayed yellow, green, red, and blue rings on the viewing screen and repeated the brain scans.
Similar patterns of activity were recorded in the brain's visual cortex, mind's processing center for sight, whether a B&W banana or a yellow ring were viewed. This relationship existed for the other basic colors tested.
The finding suggests that the mind registers basic colors even when they are absent from the scenery.
"It was particularly interesting that the colors of the objects were only encoded in the primary visual cortex," said co-author Michael Bannert, a fellow neuroscientist at Tübingen. The primary visual cortex is one of the first places a visual signal arrives in the brain, according to the authors.
The authors propose that our mind's automatic coloring book helps us recognize objects in difficult and noisy environments, like fog or when the weather is overcast.
But alternatively, when people's minds rely too heavily on predicting colors, then they may have hallucinations or pathological perception of illusions.
"This result shows that higher-level prior knowledge — in this case of object-colors — is projected onto the earliest stages of visual processing," said co-author Dr. Andreas Bartels, a neuroscientist at Tübingen and expert in visual perception.
Source: Bannert M, Bartels A. Decoding the Yellow of a Gray Banana. Current Biology. 2013.
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