Oddly enough, red and yellow in nature frequently signal to predators that an animal is venomous, poisonous, or unpalatable, Putnam said. Think of the red hourglass marking on a black widow spider, or the bright yellows and reds of certain venomous snakes.
“But colors evolved for many different reasons,” Putnam said, adding that certain birds gravitate to red since it is a “sexualized” color for them, as it is for humans.
Lizards and other animals see the world somewhat differently than we do, however, as a result of their particular visual systems. Lizards, for example, have four retinal cones while humans have three. The fourth cone peaks in sensitivity in the ultraviolet range, allowing them to likely see UV wavelengths.
“We had to be careful not to wash our clothes with regular laundry detergent because they often contain brighteners (phosphors), which essentially enhance the UV-reflectance of clothes, making them appear brighter and clear to us,” Putnam said, adding that lizards would probably be sensitive to this UV effect.
The scent of laundry detergent, softeners, of bleach could also affect how an animal reacts to a person.
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While researchers are just beginning to understand the impact clothing has on animals, Putnam advises fieldworkers to wear the same clothes every time they conduct their studies on animals “so clothing color does not have a systematic effect,” she explained.
For others — even owners of skittish pets — she said, “You could do a test to determine whether you are able to get closer to an animal by wearing its specific body color or just a dull color. I’m sure the responses are going to be species-specific, so it is hard to make generalizations.”