The world might seem a little greyer than usual when we're down in the dumps and 'feeling blue', according to new research which suggests that sadness may actually change how we perceive colour.
Specifically, researchers found that participants who were induced to feel sad were less accurate in identifying colours on the blue-yellow axis than those who were led to feel amused or emotionally neutral.
"Our results show that mood and emotion can affect how we see the world around us," said psychology researcher Christopher Thorstenson of the University of Rochester in New York, first author on the research.
"Our work advances the study of perception by showing that sadness specifically impairs basic visual processes that are involved in perceiving colour," said Thorstenson.
Previous studies have shown that emotion can influence various visual processes, and some work has even indicated a link between depressed mood and reduced sensitivity to visual contrast.
Because contrast sensitivity is a basic visual process involved in colour perception, Thorstenson and co-authors Adam Pazda and Andrew Elliot wondered whether there might be a specific link between sadness and our ability to perceive colour.
"We were already deeply familiar with how often people use colour terms to describe common phenomena, like mood, even when these concepts seem unrelated," said Thorstenson.
"We thought that maybe a reason these metaphors emerge was because there really was a connection between mood and perceiving colours in a different way," he said.
In one study, the researchers had 127 undergraduate participants watch an emotional film clip and then complete a visual judgement task.
The participants were randomly assigned to watch an animated film clip intended to induce sadness or a standup comedy clip intended to induce amusement.
After watching the video clip, the participants were then shown 48 consecutive, desaturated colour patches and were asked to indicate whether each patch was red, yellow, green, or blue.
The results showed that participants who watched the sadness video clip were less accurate in identifying colours than participants who watched the amusing clip, but only for colour patches that were on the blue-yellow axis. They showed no difference in accuracy for colours on the red-green axis.
And a second study with 130 undergraduate participants showed the same effect in comparison to a neutral film clip: Participants who watched a sad clip were less accurate in identifying colours on the blue-yellow spectrum than those who watched a neutral screen-saver.
The findings suggest that sadness is specifically responsible for the differences in colour perception.
The research was published in the journal Psychological Science.