There is an irony to referring to low moods as “the blues”, a new study has found, because sadness actually interferes with our ability to see color, particularly shades of blue.
Our emotions are known to be able to affect our processing of visual information, including contrast sensitivity. The University of Rochester's Christopher Thorstenson wondered if this would influence our color perception.
"We were already deeply familiar with how often people use color terms to describe common phenomena, like mood, even when these concepts seem unrelated," said Thorstenson, who led the study, in a statement. "We thought that maybe a reason these metaphors emerge was because there really was a connection between mood and perceiving colors in a different way."
Thorstenson had 127 undergraduate students watch a randomly assigned film clip, and then shown 48 faintly colored patches and asked to classify them as red, yellow, green or blue. The film had no affect on red-green perception, but those assigned a clip previously verified to induce sadness were less able to identify colors on the blue-yellow axis than those shown a funny film.
Thorstenson conducted a second study, this time with 130 subjects, comparing the effect of the sad clip to a neutral test film. Not only did this show that it was the sadness that affects color perception, rather than amusement enhancing it, but it added support to the initial study's reliability, valuable in the light of recent findings on the replicability of psychology papers. The findings from both experiments were published in Psychological Science.
The fact that effect was only observed for certain colors also gave Thorstenson confidence that that the results are not a result of sad participants being less motivated to engage with the experiment. "We were surprised by how specific the effect was, that color was only impaired along the blue-yellow axis," he added in the statement.
In a quest to explain the finding the researchers turned to work showing that blue color perception relies on dopamine, the neurotransmitter well known for its importance in our reward systems. The nervous system uses dopamine in a wide variety of roles, which is why the shortage induced by Parkinson's disease has such widespread effects. The neurotransmitter is involved in signalling in the retina of the eye. It seems possible that at least part of the reason for this is to transmit observations of color.
"We did not predict this specific finding, although it might give us a clue to the reason for the effect in neurotransmitter functioning,” said Thorstenson in the statement.
The link to dopamine could explain other circumstances where blue-yellow perception is affected, including ADHD and depression of a more sustained form than that produced by watching sad bits from the Lion King.
It has only recently been revealed how words for blue are relatively new in human languages compared to other colors, with indications that previously people did not perceive those things we now see as blue the same way we do. Whether this is connected to these findings provides an intriguing avenue for future research.