How smell affects the colours we “think” we see….

Ward and teammates found that “Odors for instance are often perceived with visual cues; these sensations interact to form our own subjective experience. This integration process can have a profound impact on the resulting experience and can alter our subjective reality. . . . Vision is dominant in our multisensory perception and can influence how we perceive information in our other senses, including olfaction. We explored the effect that different odors have on human color perception by presenting olfactory stimuli while asking observers to adjust a color patch to be devoid of hue (neutral gray task). . . . For instance, when asking observers to perform the neutral gray task while presenting the smell of cherry, the perceptually achromatic stimulus was biased toward a red-brown.”  When study participants the odor of caramel was associated with dark brown, the odor of cherry with pink, red, and purple, lemon with yellow, green, and pink and peppermint with green and blue, for example.  So, while smelling coffee, a gray square was seen as more reddish-brown in color than when study participants were not smelling the coffee.

Ryan Ward, Maliha Ashraf, Sophie Wuerger, and Alan Marshall.  2023. “Odors Modulate Color Appearance.” Frontiers in Psychology, vol. 14, https://doi.org/10.3389/fpsyg.2023.1175703