New York, Sep 3 (IANS): Taking the association between our mood and colours beyond a mere metaphor, new research has found that feeling sad can impair our ability to accurately identify colours on the blue-yellow axis.

"Our results show that mood and emotion can affect how we see the world around us," said study first author Christopher Thorstenson from University of Rochester in New York, US.

"Our work advances the study of perception by showing that sadness specifically impairs basic visual processes that are involved in perceiving colour," Thorstenson noted.

In the study, the researchers had 127 undergraduate participants watch an emotional film clip and then complete a visual judgment 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.

The results cannot be explained by differences in participants' level of effort, attention, or engagement with the task, as colour perception was only impaired on the blue-yellow axis.

"We did not predict this specific finding, although it might give us a clue to the reason for the effect in neurotransmitter functioning," Thorstenson said.

The researchers noted that previous work has specifically linked colour perception on the blue-yellow axis with the neurotransmitter dopamine.

The new research was published in the journal Psychological Science.