Neuroscience: Feeling warmth with the blues

Blue objects feel warmer than red objects, a small study published in Scientific Reports suggests, opposing the prevailing association that reddish colours inducing warm feelings and bluish colours inducing cold feelings. These findings may provide insights into how our brain integrates the multisensory information when estimating an object property.

Hsin-Ni Ho and co-workers asked 12 participants to report the perceived temperature when touching the surface of a red or blue object. On average, temperatures of the red objects needed to be 0.5 degrees C higher than blue objects to feel warm, indicating that at the same physical temperature a blue object is more likely to be judged as warm than a red object. The authors suggest that outcome this due to expectations that a red object will inevitably feeler warmer in general, so it takes a lower temperature for the blue object to feel warm compared to the red. They also note that the colour of the hand (altered by projecting blue or red colours onto the hand) in contact with the object can impact how warm the object feels. Although hand temperatures remained constant throughout the experiments, objects felt warmer when touched with a red hand than a blue hand because of the perceived temperature difference between the hand and the object, the authors explain.

These results indicate that our brain integrates prior expectations about object and hand temperatures (based on perceptions associated with colour) with direct temperature inputs in a way that emphasizes unexpected information, the authors conclude.