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Emotions are human states that have measurable behavioral, cognitive and physiological consequences. The emotional response to a stimulus has two stages: a primary sensory-motor response that is outside of awareness (bodily response); and a secondary process of awareness of one's own emotional experience.1
Emotions play a central role in the lives of human beings. They are much more than chemical reactions or automatic responses since they provide valuable information about the self, interactions with other people and the environment. Ekman determined in 1972 that human beings have six basic emotions: sadness, happiness, surprise, disgust, fear and anger.2 These emotions are expressed through facial gestures, physiological responses, tone of voice and body language. Such expressions establish bonds, strengthen relationships and build greater empathy between people.
Emotions appear as a response to an external stimulus, as postulated by the James-Lange theory (see Figure 1).3 This can be a consumer experiencing a perfume, the application of makeup or a skin care product, etc. The perception the consumer has about the performance of the product – positive or negative – generates a physiological response that is later translated into an emotion toward said stimulus.
Figure 1. James-Lange theory of the experience of using cosmetic products
Interestingly, some studies have shown that the perception of stimuli can change with age. For example, older individuals are less capable of discriminating music or other stimuli that express a peaceful versus sad versus threatening tone.4
The study of emotions is of great interest to the cosmetics industry.5 Consumers’ physiological responses to cosmetic products can influence a product’s success and/or uncover opportunities for improvement – and neuroscience offers non-invasive techniques to assess neurocognitive responses to formulations, advertising, marketing and branding elements. More specifically, it captures the visceral, somatic and neural responses that occur in an individual's body after exposure to a certain stimulus, such as using cosmetics.
Consumers’ physiological responses can be classified according to the peripheral or central nervous systems;6 Table 1 outlines these response systems and the evaluation methods traditionally used for each. The objective of these methods is to evaluate three key aspects in the consumer: attention, memory and/or emotion.7 
Table 1. Consumer Response Systems and Evaluation Methods
Attention refers to the capacity of the stimulus produced by a cosmetic product or brand to capture the interest of the consumer and maintain it. Emotion refers to the ability of a product to generate an emotional response in the consumer, while memory refers to the ability of the stimulus to be remembered. Table 2 presents techniques to evaluate these three parameters.
Table 2. Evaluation Techniques and Their Scope in Terms of Attention, Memory and Emotion
Since facial expressions communicate emotion and help to establish bonds between people, the interpretation of these facial expressions is another piece of the neuroscience puzzle. This was the focus of the study described here.
Panelists (n = 493) reviewed photographs of two women making facial expressions and estimated their ages. During their review, 10 panelists also participated in eye tracking to determine where, in the photographs, their eyes focused; eye tracking, as noted in Table 2, can capture the attention and memory aspects of a consumer exposed to a stimulus.
The results demonstrated how facial expressions can impact perceived age. In addition, they revealed the characteristics in the photographs that attracted viewer interest, influencing age perception, as will be shown.
Materials and Methods
Emotion expression: Six photographs of two different women (woman #1 and woman #2) showing a different emotion in each were used for this study (see Figure 2).
Figure 2. Photographs Used Depicting Each Emotion
Panelists: A panel of 493 men and women between the ages of 20 and 60 were convened to estimate the age of the women shown in the photographs. Each panelist reviewed only one photograph.
Eye tracking and attention evaluation: As noted, 10 panelists between 30 and 50 years old from the same group participated in eye trackinga as they reviewed the photographs. The justification for using eye tracking lies in the premise that it provides observable proof of the way a person attends to visual stimuli over time. Visual attention is defined as a selectivity in perception. It is the psychological construct of an individual’s greatest interest as determined by eye movements.
Eye tracking captures four main parameters: what the viewer looks at, when, how often and for how long.8 Analysis of these parameters determines what attracts the most attention; previous studies, for example, have shown that people pay more attention to the areas of images showing more visible signs of aging.6 Eye tracking readings display where visual attention is present and the intensity of that attention using a heat map.
Statistical analysis: All results were analyzed using non-parametric statistics (Mann-Whitney test).
Results and Analysis: Emotion Expression
Woman #1: Figure 3 shows how the emotions expressed in photographs by woman #1 affected panelists’ perceptions of age. The emotion of surprise had a significantly lower (p < 0.05) perceived age (28.8 years on average) compared with all other emotions, whereas disgust had a significantly higher (p < 0.05) perceived age (35.9 years on average) than all other emotions except anger.
Figure 3. Perceived age comparison for woman #1
Woman #2: Figure 4 shows the influence of emotion on age perception for woman #2. In this case, the emotion of surprise had the least effect on perceived age compared with the other emotions (p < 0.05). Disgust had a greater impact on age perception than anger, sadness and surprise (p < 0.05); this effect was not statistically different from happiness or fear. Comparing the results for both women reveals two trends: the expression of surprise lowered the perceived age while the expression of disgust increased the perceived age. Taken together, it can be concluded that facial emotional expressions can significantly influence perceived age; Figure 5 provides a visual summary.
Figure 4. Perceived age comparison for woman #2
Figure 5. Change in perceived age
Results: Eye Tracking and Attention Evaluation
As stated, eye tracking was carried out in 10 panelists as they reviewed photographs of two women and estimated their age. Figure 6 shows results from some of the readings. These heat maps illustrate how generally, panelists’ gazes focused on areas in the photographs showing the most signs of aging. This aligns with the previous observations reported in the literature.6
Figure 6. Heat map of viewer focus
Conclusion
The work described here shows how facial emotional expressions can affect the perceived age of individuals. Certain emotions, such as disgust, accentuated signs of aging, resulting in a higher perceived age; this could be due to the viewers’ attention being more heavily focused on signs of aging in the photos. In contrast, the emotion of surprise significantly decreased the perceived age.
This methodology and these findings could be used to evaluate branding elements in cosmetic products, such as advertising, packaging, labels, graphic design, etc. They also could be used to evaluate user responses to skin care and makeup products. They may even inspire the development of new concepts that tie into emotion; e.g., products to mitigate perceived aging by affecting facial emotional expressions.
a Tobii EyeCore eye-tracking equipment with Windows software
References
1. Churchill, A. and Behan, J. (2010). Comparison of methods used to study consumer emotions associated with fragrance. Available at https://psycnet.apa.org/record/2010-22681-017
2. Ekman, P. (1999). Handbook of Cognition and Emotion. John Wiley & Sons Ltda. Available at https://onlinelibrary.wiley.com/doi/book/10.1002/0470013494
3. Craig, A.D. (2004, Jun). Human feelings: why are some more aware than others? Trends in Cognitive Sciences. Available at https://pubmed.ncbi.nlm.nih.gov/15165543/
4. Viellard, S., Didierjean, A. and Maquestiaux, F. (2012). Changes in the perception and the psychological structure of musical emotions with advancing age. Available at https://pubmed.ncbi.nlm.nih.gov/22830668
5. Grabenhofer, R. (2020, May). Industry Insight. Excited State: How Emotions Can Supercharge Cosmetics. Cosmetics & Toiletries. Available at https://www.cosmeticsandtoiletries.com/research/consumers-market/article/21835766/industry-insight-how-emotions-can-supercharge-cosmetics#:~:text=In%20summary%2C%20we%20can%20say,the%20skin%20related%20to%20beauty.
6. Casado, L. (2021). Neurociencia del consumidor. Ediciones Pirámide. Emoción y proceso de toma de decisiones del consumidor. Available at https://www.edicionespiramide.es/libro.php?id=6839023
7. Jiménez, J. (2023, Jul). Attention, memory and emotion. Available at https://www.eurocosmetics-mag.com/attention-memory-and-emotion/
8. Jiménez, J. (2017, Mar). Soft-focus for the selfie obsessed. Eye tracking to improve color formula development. Available at https://www.cosmeticsandtoiletries.com/testing/method-process/article/21836734
