We might think we know which color do what. The idea that red wakes us up or blue calms us down is deeply rooted in Western culture-to the point where many consider it a fact. But do colors really change our behavior in the ways that we     1    ?

When it comes to scientific research, the results are     2    . Red is the color that gets studied most often and tends to be compared with either blue or green. Some studies have found that people do better on cognitive tasks when faced with red rather than blue or green; others show the opposite. The mechanism most often cited is conditioning (条件反射). If you repeatedly have a particular     3     surrounded by a certain color, you eventually begin to associate that color with the way you are feeling or behaving.

Clearly, studying the effect of colors is much harder than it sounds. In Switzerland, 20 percent of prisons and police stations have at least one pink prison. The color was first proposed as a way to help reduce aggression (攻击性. In 2014，Oliver Gens-chow at the University of Basel and his team entered a prison in Switzerland to     4     the hypothesis. Prisoners were     5     assigned to cells either painted pink all over or with grey on the walls and white on the ceiling. Prison officers were trained to use an aggression     6     to assess the subject's behavior over three days. To their disappointment, the prisoners in both cells demonstrated less aggression over their time     7    . The color of the walls made no difference at all.

The researchers say that if the color makes a difference to a few people, authorities need to reconsider whether it's worthwhile. They even suggest that pink walls might have negative effects if prisoners fell offended by having a     8    feminine (女性的) color on the walls.

So colors might well have an effect, but so far those effects have been difficult to     9     consistently and sometimes don't seem to exist at all. Better-controlled studies are slowly emerging. It may be some time before we get a full     10     of how colors affect us, let alone understand the exact mechanisms through which it happens.