The Biological Basis for Color Perception

Research suggests that color perception is rooted in biology, as babies have been observed to distinctly categorize colors into red, blue, green, yellow and purple prior to learning a language.

The latest research out of Stanford University, published in Proceedings of the National Academy of Sciences seems to tip the longstanding debate whether color is a construct of biology or culture in favor of biology.

The basis of the debate is that speakers of languages who lack words for certain colors seem to have a harder time differentiating them. For example, in English there are approximately 10 words to describe color hues. In comparison, tribes like the Himba have far fewer words for colors, here are their definitions:

  • Zoozu- mostly dark colors, includes reds, blues, greens and purples
  • Vapa- mainly white and some yellow
  • Borou- some greens and blues
  • Dumbu- different greens but also reds and browns

Due to the discrepancy in color lexicon, Most Westerners have a hard time distinguishing which color is different than the rest in diagram A:

Answer shown in B

That’s because English speakers group all the squares under “green.” But the Himba quickly differentiate it because they have more words for the variations of green.

Inversely, when presented with the following image, the Himbas take a much longer time distinguishing the difference between what Westerners would describe as green and blue, as the Himba don’t have a different word for it.

The same phenomenon is observed even when comparing the speed of distinguishing the color blue between English speakers and Russian speakers, as the Russian more words for specific variations of blue.

The Experiment

Researchers analyzed the response of 176 babies (between the ages of four and six months) to color samples.

Each baby was seated in front of 2 panels, both filled with the same color. Suddenly, one of the panels changed to a different color as the baby’s reaction was observed and recorded. The researchers analyzed the video recordings, looking for “novelty preference” which is a bias towards the new; if a baby looked longer at the different color, that would suggest that it has recognized it as different.

“In total, 14 different colors of the same lightness were used, spanning the color spectrum. While some infants were shown pairs of colors very close to each other, others were shown pairs slightly further apart to probe where the babies’ boundaries fell for colors categories.”

The experiment concluded that babies are able to distinguish five distinct color categories: red, yellow, green, blue and purple.

Those categories were compared to those found in English, and to 110 languages from non-industrialized countries, which all aligned well with the babies’ categories.

“Furthermore, four of the infants’ color boundaries were found to map to the four extremes produced by signals from different cone types when they are combined and interpreted by the brain.”

The findings suggest a biological basis of color which is then influenced by culture, language, and environment.

Conclusion

Although this is interesting news, further experiments are needed to test babies of different ethnicities and cultures to account for possible preconditioning by environmental factors such as toys to see if the five categories are universal.