Investigating the validity of the hue-heat effect on thermal sensitivity

Abstract

In this study, we aimed to investigate the validity of the hue-heat effect on the body thermal sensitivity. Previous research on thermal comfort has proposed associations between red and warmth, and blue with cold. However, inconsistencies in confirming this effect have arisen, with studies often relying on subjective scales for thermal comfort assessment, introducing potential confounding variables. To overcome these limitations, we conducted a study focusing on the hue-heat effect within the domain of thermal sensitivity, providing a more objective measurement of thermal perception. Participants (n = 26) were required to compare the perceived temperatures inside different climate chambers lighted by either red or blue lights following two different paradigms. In the congruent paradigm, the warmest chamber was lighted by red lights, while the coldest chamber had blue lights. On the contrary, the incongruent condition featured the warmest chamber with blue lights and the coldest chamber with red lights, thereby violating the hue-heat effect. We found comparable performance in both conditions, challenging the hypothesis that congruence between colour and temperature enhances thermal perception. Notably, some participants aligned with our hypothesis, while others exhibited opposing behaviour, highlighting the potentially subjective nature of the hue-heat effect. Furthermore, we compared the present results with our previous data without the added stimuli of the lights. Surprisingly, the sensitivity observed in this experiment was even lower than the one measured in our previous study (p-value < 0.0001), suggesting that the colour of the lights might have increased participants' cognitive load, leading to a decline in their performance.

Keywords: Colour-temperature association; Multisensory perception; Thermal comfort; Thermal perception.

Fig. 1

Interaction effect between the differences in temperature and the type of condition. The black marks on the x-axis indicate the distribution of the data along the tested temperature range.

Fig. 2

Panel (a) shows the effect of colour on participants’ probability of saying “warmer”. Panel (b) shows the psychometric functions when the target chamber had blue versus red lights.

Fig. 3

JND in the congruent and incongruent conditions for each participant. In black are highlighted the participants who behaved opposite to what was expected (i.e., those who JND in the incongruent condition is smaller than in the congruent one).

Fig. 4

Panel (a) shows the effect of colour on participants’ probability of saying “warmer” for the group who behaved as expected. Panel (b) shows the psychometric functions when the target chamber had blue versus red lights for the group who behaved as expected.

Fig. 5

Panel (a) shows the effect of colour on participants’ probability of saying “warmer” for the group who behaved opposite to what was expected. Panel (b) shows the psychometric functions when the target chamber had blue versus red lights for the group who behaved opposite to what was expected.

Fig. 6

Example of how the climate chambers looked like with the red (left) and blue lights (right) turned on © Eurac Research | Andrea De Giovanni.