A blue mood may be more than just a figure of speech. Your mood may also affect how you perceive the world around you, according to a new study. A team of researchers has demonstrated that sadness could have an effect on the way we see colour.
The team, led by psychology researcher Christopher Thorstenson of the University of Rochester, found that people in whom they had induced a sad mood were less accurate in identifying colours on the blue-yellow axis, compared to people who weren't feeling sad.
"We were already deeply familiar with how often people use colour terms to describe common phenomena, like mood, even when these concepts seem unrelated," Thorstenson said in a statement. "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."
Thorstenson and his team are not the first to identify a link between a depressed mood and a difference in perception. In 2010, Emanuel Bubl and his team at Albert Ludwigs University Freiburg in Germany demonstrated a link between decreased contrast sensitivity and depression. This was supported by a 2013 paper by Johnson Fam et al of the University of Singapore.
It was this research that led Thorstenson and his team to wonder if there was a connection between sadness and colour perception.
The team conducted two studies. In the first, 127 participants were randomly assigned to watch one of two video clips, which had been proven in previous studies to induce either sadness (an animated clip) or amusement (a stand-up comedy routine).
The entire group was then tasked with identifying the colours in 48 consecutive, desaturated colour swatches. The group that had been shown the animated clip was measurably worse at identifying colours along the blue-yellow axis, although no difference was found along the red-green axis.
For the second study, 130 participants were randomly assigned to watch either a sad clip or a screensaver clip that was judged to be "neutral". The sadness group demonstrated reduced ability to identify colours along the blue-yellow axis than the neutral group. Again, there was no difference along the red-green axis.
Because of this lack of difference along the red-green axis, the researchers say, the difference in ability cannot be explained by lack of effort, or focus. If the subjects were badly focused, they would have performed equally badly along both colour axes.
"We were surprised by how specific the effect was, that colour was only impaired along the blue-yellow axis," Thorstenson said. "We did not predict this specific finding, although it might give us a clue to the reason for the effect in neurotransmitter functioning."
Previous research has linked blue-yellow to dopamine. In 2013, a paper led by Lea Hulka of the University of Zürich found that blue-yellow vision impairment was common in cocaine users, and linked that impairment to drug-induced changes in retinal dopamine neurotransmission.
Because this is new research, Thorstenson said, it will need to be rigorously confirmed before any further conclusions can be drawn, or future applications planned. "This is new work and we need to take time to determine the robustness and generalisability of this phenomenon before making links to application," he said.