Emotive Colors

We have a sophisticated set of sensors that we use everyday and usually take for granted. But in interpreting the electrical signals from the sensors our brain has to do a great deal of processing whilst multitasking. Cross-talk occurs, of course, and this is often put to good use. As we build up our databank through experience, we can cut the processing time and jump to the final result, which may not always be correct. There are many examples of optical illusions with which we’ve been entertained.

Our everyday world seems to be three-dimensional and change with time, so our brains are geared to turn the signals from our retinas into an understanding of the three-dimensional forms in front of us. Light, shade and perspective is what we think of immediately as supplying those clues, and artists have been working their magic with these since the renaissance.

Apparently surface texture is also a major clue to shape. Fleming et al in the Proceedings of the National Academy of Science, (1), have shown 2-D shapes patterned from random (“white”) noise and their subjects saw 3-D shapes. The more intense the pattern, the more 3-D the shape appeared to be.

Sometimes the cross-talk can be interesting, though. An extreme example is seen with people who are synesthetic and see sounds as distinct colors. Some recent work by Ludwig et al has shown that this interaction between sound and color is widespread (2). Of course, you and I expected that already.

The sound/color experiment used thirty-three humans and six chimpanzees. (Note; that there were no political implications in the choice of participants.) The candidates had to classify black or white squares while listening to background noise. The noise was irrelevant to the task in hand and was either high pitch or low pitch.

Both humans and chimps found it easier to pick out the white squares when the sounds were high pitched, and the black when it was low pitched. So high noises are brighter (higher luminance) and low pitched are darker. One has to think about film background music when the low notes dominate and our spines shiver, and then it’s all over and the music gets lighter and higher as we move into the sunshine, and all is well after all.

  1. http://www.pnas.org/content/early/2011/12/05/1114619109.full.pdf+html 
  2. http://www.pnas.org/content/early/2011/11/29/1112605108.abstract 

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