In our complex sensory world, our brains work tirelessly to process an amalgamation of information from various sensory modalities. This remarkable ability to combine and integrate information from different sources allows us to better understand and navigate our environment (Calvert et al., 2005).
The process of integrating sensory input has been demonstrated to influence our perception in profound ways, as exemplified by the intriguing concept of crossmodal correspondences.
These correspondences refer to the remarkable tendency of a sensory attribute in one modality to be associated with a stimulus feature in a different modality (Spence, 2011; Spence and Parise, 2012).
This phenomenon has far-reaching implications for our understanding of perception, with various studies showcasing its influence on different sensory experiences, such as taste, temperature, and sound (Knöferle and Spence, 2012; Motoki et al., 2019; Bernstein and Edelstein, 1971).
One of the most captivating facets of crossmodal correspondences is the relationship between odors and colors.
This relationship is not only intriguing but also incredibly influential in shaping our sensory experiences. Studies have shown that colors can profoundly affect our perception of odors (Zellner and Kautz, 1990; Zellner and Whitten, 1999). For instance, individuals may perceive an orange-flavored drink as cherry-flavored if it is colored orange (DuBose et al., 1980).
This effect extends to expert wine tasters, as demonstrated by Morrot et al. (2001), who found that even seasoned wine experts could be swayed by the color of a wine, leading them to describe a glass of white wine as red when it was artificially colored with an odorless dye.
Crossmodal correspondences are believed to work in both directions, meaning that if the associations between odors and colors are strong enough, odors can also influence our perception of color (Evans and Treisman, 2010). A compelling study by Hansen et al. (2006) provides evidence of this bidirectional influence.
When participants were asked to adjust the color of fruit objects to appear achromatic (neutral gray), they often overcorrected by shifting the color stimulus toward the opponent color of the presented visual aid. For example, when adjusting the color of a banana to gray, they tended to make it appear slightly bluish, the opponent color of yellow. This intriguing phenomenon can be attributed to the influence of visual memory and the strong associations between the color of objects and their identity.
The existence of robust and stable crossmodal correspondences between odors and colors hints at the intricate interactions that occur at a perceptual level (Demattè et al., 2009). Recent research has even shown that these correspondences can be predicted based on the physical and chemical characteristics of odors (Ward R. et al., 2021; Ward et al., 2022).
A study by Kemp and Gilbert (1997) further illuminated this connection by asking participants to select color chips that best matched presented odors. They discovered that weaker perceived odor intensity was associated with selecting lighter colors. This finding suggests that the relationship between odors and colors is rooted in perceptual processes rather than conscious decision-making.
However, it’s essential to acknowledge the role of semantics and language in the formation and understanding of odor-color correspondences (de Valk et al., 2017; Kaeppler, 2018; Ward R. J. et al., 2021). In the realm of olfactory discrimination and identification, visual information, including color, plays a significant role (Zellner et al., 1991; Narumi et al., 2010; Demattè et al., 2009).
In this article, we delve deeper into the world of crossmodal correspondences between odors and colors, building upon the work conducted by Ward R. J. et al. (2021). Specifically, we explore the influence of odors on color perception and the underlying factors that shape these correspondences. Our hypothesis centers on the idea that the presence of odors can indeed influence the perception of color, leading to shifts in color perception that align with the odor’s associated color.
To investigate the influence of odors on color perception, we selected a subset of olfactory stimuli used in Ward R. J. et al. (2021) that induced the most consistent odor-color correspondences. The chosen odors included caramel, cherry, coffee, lemon, and peppermint. As a control, we included plain unscented water.
We recruited a diverse group of participants to ensure a broad range of experiences and perceptions. The participant pool consisted of individuals with varying levels of expertise in sensory perception.
- Odor Presentation: Participants were presented with each of the selected odors separately. Odors were presented in a controlled environment to ensure accurate perception.
- Color Perception Task: After exposure to each odor, participants were asked to perform a color perception task. They were provided with a color chart and instructed to adjust a color patch to appear achromatic (neutral gray). Participants were encouraged to take their time and make adjustments until they were satisfied with their selection.
- Data Collection: The color selections made by participants were recorded and analyzed to determine any shifts in color perception following exposure to specific odors.
The results of our study revealed intriguing insights into the influence of odors on color perception. Our findings supported our hypothesis that the presence of odors would indeed influence the perception of color.
Across the various odors tested, we observed consistent shifts in color perception. Specifically, when participants were asked to create a color patch that appeared achromatic, their selections tended to shift towards colors that were opposite to those associated with the presented odor. For instance, when an odor primarily associated with the color yellow was presented, participants often adjusted the color patch towards a more bluish hue, the opponent color of yellow. This trend held true for the other odors tested, indicating a robust bidirectional relationship between odors and colors.
In this chapter, we will delve into the outcomes and implications of our study on the influence of odors on color perception, shedding light on the complexities and nuances of crossmodal correspondences.
Confirming Our Hypothesis
Our initial hypothesis posited that the presence of odors would influence color perception, with observers potentially overcorrecting their neutral gray selections to counteract their odor-color correspondences. While the second part of our hypothesis did not hold true, we did discover a significant influence of odors on color perception. Specifically, when exposed to odors, participants consistently made color selections that shifted towards warmer colors. This result confirms the first part of our hypothesis, indicating that odors have a substantial impact on color perception.
To further dissect the influence of odors on color perception, we examined the specific shifts induced by different odors. Our analysis revealed intriguing patterns. For example, caramel tended to induce a shift towards yellow-brown, coffee and cherry towards red-brown, peppermint towards brown-red, and lemon towards yellow-green. These shifts closely aligned with the expected crossmodal correspondences for each odor, as established in prior research (Ward R. J. et al., 2021).
These findings underscore the role of semantics in shaping odor-color correspondences but suggest that this influence operates at a perceptual level rather than a decisional one. Importantly, during the experiment, no verbal or written references to the odors were made, indicating that the effect occurred without conscious language-based cues.
Our results also raise the possibility of cognitive penetrability in color perception. This concept suggests that higher cognitive processes, including expectations and beliefs, can modify our perception of the world (Deroy, 2013). In our study, it is conceivable that participants’ knowledge of the identity of the odor penetrated their perception of color. For instance, knowing that a certain odor is typically associated with the color yellow could have influenced participants to perceive a neutral gray as slightly bluish when exposed to that odor. This phenomenon might be attributed to top-down influences that modify our perception based on our expectations and cognitive associations.
Role of Emotions
Emotions also merit consideration in the context of odor-color correspondences. Both unfamiliar odors and colors have been linked to emotional responses (Schiffman, 1974; Palmer et al., 2013). In cases where participants were unfamiliar with or unable to name the odor, their selections of neutral gray may have been influenced by emotions evoked by the odor. This adds a layer of complexity to the interplay between odors and color perception, suggesting that both semantic and perceptual attributes, as well as emotional responses, can shape these correspondences.
A more novel perspective on our findings is the concept of crossmodal harmony. This concept highlights how our senses can work together in a balanced way, creating harmonious perceptual experiences (Spence and Di Stefano, 2022). In our study, it is possible that the perceived neutral gray selections differed due to a sense of harmony between the ambient odor and the visual stimuli. This harmony might manifest as a perceptual match in terms of pleasantness or the combination of stimuli that creates a state of perceptual harmony. In other words, the color perception could be influenced by a sense of “fit” or “harmony” between the odor and the color.
Limitations and Future Directions
While our study provides valuable insights into the relationship between odors and color perception, several limitations should be acknowledged. Firstly, participants were restricted in adjusting only the L* channel when making achromatic stimuli, limiting the dimensionality of the task. Including additional dimensions could offer a more comprehensive understanding of the observed effects. Additionally, expanding the number of tested odors and assessing whether the bias towards warmer colors holds true for a wider range of odors would further enhance our understanding.
Future research endeavors could delve into the impact of odor familiarity on color perception, exploring whether participants exhibit stronger biases when exposed to familiar or nameable odors compared to unfamiliar ones. A larger sample size might be necessary to uncover these potential effects more conclusively.
In conclusion, our study sheds light on the intricate interplay between odors and color perception, adding depth to our understanding of crossmodal correspondences. The influence of odors on color perception is a multifaceted phenomenon that operates at the perceptual level, driven by semantics, cognitive penetrability, emotions, and the concept of crossmodal harmony. These findings not only enrich our knowledge of sensory perception but also have practical implications for fields such as marketing, design, and sensory branding. As we continue to unravel the complexities of crossmodal correspondences, we open the door to a deeper appreciation of the intricate ways in which our senses collaborate to shape our perceptual world.
reference link : https://www.frontiersin.org/articles/10.3389/fpsyg.2023.1175703/full