Are prisoners calmer when their cells are painted pink?

On the back of research first published in 70s and 80s, an increasing number of jails in the Western world are painting their cells pink, in the belief that doing so has a calming effect on prisoners.

Unfortunately, this early research was poorly designed. For example, one study found that prisoners' strength, pushing against an experimenter, was reduced when they were presented with a pink vs. blue coloured card. But the experimenter could also see the card and may simply have exerted more effort in the pink condition.

Another early study reported that prisoners were calmer in pink cells versus white cells. But the prisoners in the pink cells were monitored one year, and the white cell prisoners during another year. Also, prisoners were not randomly allocated to the different colours. Both these shortcomings make it difficult to rule out other influences, besides the paint colour on the cell walls.

Now a team of psychologists led by Oliver Genschow at Ghent University has provided the first carefully controlled systematic test of the pink cell claim. They trained guards to measure the aggressive behaviour of 59 male prisoners in Switzerland, who were placed into special detention as punishment for violating prison regulations. Half these prisoners were chosen at random to be placed into cells painted entirely pink, across the floor, walls and ceiling. The other half were placed into cells of identical size, but painted white, with a grey floor. Aggression ratings were taken on arrival in the cells and after three days.

The prisoners showed reduced aggression at the end of three days, compared with at their arrival, but crucially, at no time was there a difference in aggression levels (in terms of emotions or behaviour) between prisoners in the differently coloured cells. The same null result was found when analysis was restricted to just those prisoners who started off low in aggression, or just those who started off with higher aggression.

Genschow and his team said their results question the wisdom of painting prisoners' cells pink. In fact, they speculate that doing so could even be counter-productive: "Being placed in a pink detention cell may … attack inmates' perceived manhood and/or cause feelings of humiliation."