Effects of Face and Background Color on Facial Expression Perception

Facial expressions affect the memory of facial colors

Facial color influences the perception of facial expressions, and emotional expressions bias how facial color is remembered. However, it remains unclear whether facial expressions affect daily facial color memory. The memory color effect demonstrates that knowledge about typical colors affects the perception of the actual color of given objects. To investigate the effect of facial color memory, we examined whether the memory color effect for faces varies depending on facial expression. We calculated the subjective achromatic point of the facial expression image stimulus and compared the degree to which it was shifted from the actual achromatic point between facial expression conditions. We hypothesized that if the memory of facial color is influenced by the facial expression color (e.g., anger is a warm color, fear is a cold color), then the subjective achromatic point would vary with facial expression. In Experiment 1, we recruited 13 participants who adjusted the color of facial expression stimuli (anger, neutral, and fear) and a banana stimulus to be achromatic. No significant differences in the subjective achromatic point between facial expressions were observed. Subsequently, we conducted Experiment 2 with 23 participants because Experiment 1 did not account for the sensitivity to color changes on the face; humans perceive greater color differences in faces than in non-faces. Participants selected which facial color they believed the expression stimulus appeared to be, choosing one of two options provided to them. The results indicated that the subjective achromatic points of anger and fear faces significantly shifted toward the opposite color direction compared with neutral faces in the brief presentation condition. This research suggests that the memory color of faces differs depending on facial expressions and supports the idea that the perception of emotional expressions can bias facial color memory.

The effect of facial colour on implicit facial expressions

Humans recognise reddish-coloured faces as angry. However, does facial colour also affect "implicit" facial expression perception of which humans are not explicitly aware? In this study, we investigated the effects of facial colour on implicit facial expression perception. The experimental stimuli were "hybrid faces", in which the low-frequency component of the neutral facial expression image was replaced with the low-frequency component of the facial expression image of happiness or anger. In Experiment 1, we confirmed that the hybrid face stimuli were perceived as neutral and, therefore, supported implicit facial expression perception. In Experiment 2, the hybrid face stimuli were adjusted to natural and reddish facial colours, and their friendliness ratings were compared. The results showed that the expression of happiness was rated as more friendly than the expression of anger. In addition, the expression of happiness was rated as friendlier when the low-frequency happy component was red, but the friendliness rating of the expression of anger did not change when it was presented in red. In Experiment 3, we affirmed the implicit facial expression perception even in reddish colours. These results suggest that facial colour modulates the perception of implicit facial expressions in hybrid facial stimuli.

Red biases sex categorization of human bodies

Color is associated with gender information (e.g., red-female). However, little has been known on the effect of color on sex recognition of human bodies. This study aimed to investigate whether the color red could influence the categorization of human bodies by sex, and the effect of contextual information. Visual stimuli were created using body silhouettes varying along the waist-to-hip ratio from female to male shapes. These stimuli were presented in conjunction with red, green, and gray colors, which were used either as body color (Experiment 1) or background color (Experiment 2). Participants were instructed to categorize the sex of the body stimuli as either male or female by pressing labeled keys. The results showed that when red was used as a body color, it induced a bias toward feminine body perception, while when used as a background color, it induced a bias toward masculine body perception. Thus, the color red influenced the sex categorization of human bodies, which being modulated by contextual information. These findings provided novel insights into the effect of contextual color cues in sex recognition of human bodies.

Padova Emotional Dataset of Facial Expressions (PEDFE): A unique dataset of genuine and posed emotional facial expressions

Facial expressions are among the most powerful signals for human beings to convey their emotional states. Indeed, emotional facial datasets represent the most effective and controlled method of examining humans' interpretation of and reaction to various emotions. However, scientific research on emotion mainly relied on static pictures of facial expressions posed (i.e., simulated) by actors, creating a significant bias in emotion literature. This dataset tries to fill this gap, providing a considerable amount (N = 1458) of dynamic genuine (N = 707) and posed (N = 751) clips of the six universal emotions from 56 participants. The dataset is available in two versions: original clips, including participants' body and background, and modified clips, where only the face of participants is visible. Notably, the original dataset has been validated by 122 human raters, while the modified dataset has been validated by 280 human raters. Hit rates for emotion and genuineness, as well as the mean, standard deviation of genuineness, and intensity perception, are provided for each clip to allow future users to select the most appropriate clips needed to answer their scientific questions.

Red background color biases gender categorization of human faces

Color carries gender information (e.g., red-female). This study explored whether background color could influence the gender categorization of human faces. Visual stimuli were generated from faces whose sexually dimorphic content was morphed monotonically from female to male perception. The face stimulus was presented upright (Experiment 1) and inverted (Experiment 2) with three background colors (i.e., red, green, and gray). Participants were instructed to categorize the gender of the face stimulus as male or female by pressing one of two labelled keys. Results showed that a red background could bias the gender of an ambiguous upright face toward a female compared with green and gray background colors (Experiment 1). However, this red effect was diminished when the face stimulus was inverted (Experiment 2). These results suggest that red background color interacting with facial configuration features biases gender perception toward a female face, possibly through top-down processing of learned associations between the color red and femininity.

Emotional face recognition when a colored mask is worn: a cross-sectional study

Studies of the impact of face masks on emotional facial expression recognition are sparse in children. Moreover, to our knowledge no study has so far considered mask color (in adults and in children), even though this esthetic property is thought to have an impact on information processing. In order to explore these issues, the present study looked at whether first- and fifth-graders and young adults were influenced by the absence or presence (and color: pink, green, red, black, or white) of a face mask when asked to judge emotional facial expressions of fear, anger, sadness, or neutrality. Analysis of results suggested that the presence of a mask did affect the recognition of sad or fearful faces but did not influence significantly the perception of angry and neutral faces. Mask color slightly modulated the recognition of facial emotional expressions, without a systematic pattern that would allow a clear conclusion to be drawn. Moreover, none of these findings varied according to age group. The contribution of different facial areas to efficient emotion recognition is discussed with reference to methodological and theoretical considerations, and in the light of recent studies.

The shared signal hypothesis: Facial and bodily expressions of emotion mutually inform one another

Decades of research show that contextual information from the body, visual scene, and voices can facilitate judgments of facial expressions of emotion. To date, most research suggests that bodily expressions of emotion offer context for interpreting facial expressions, but not vice versa. The present research aimed to investigate the conditions under which mutual processing of facial and bodily displays of emotion facilitate and/or interfere with emotion recognition. In the current two studies, we examined whether body and face emotion recognition are enhanced through integration of shared emotion cues, and/or hindered through mixed signals (i.e., interference). We tested whether faces and bodies facilitate or interfere with emotion processing by pairing briefly presented (33 ms), backward-masked presentations of faces with supraliminally presented bodies (Experiment 1) and vice versa (Experiment 2). Both studies revealed strong support for integration effects, but not interference. Integration effects are most pronounced for low-emotional clarity facial and bodily expressions, suggesting that when more information is needed in one channel, the other channel is recruited to disentangle any ambiguity. That this occurs for briefly presented, backward-masked presentations reveals low-level visual integration of shared emotional signal value.

Feeling Blue and Getting Red: An Exploratory Study on the Effect of Color in the Processing of Emotion Information

Specific emotions and colors are associated. The current study tested whether the interference of colors with affective processing occurs solely in the semantic stage or extends to a more complex stage like the lexical processing of emotional words. We performed two experiments to determine the effect of colors on affective processing. In Experiment 1, participants completed a color-emotion priming task. The priming stimulus included a color-tinted (blue, red, and gray) image of a neutral face, followed by a target stimulus of gray-scaled emotional (angry and sad) and neutral faces after 50 ms. Experiment 2 used a modified emostroop paradigm and superimposed emotion words on the center of the color-tinted emotional and neutral faces. Results showed the priming effect of red for the angry face compared to the control, but not in blue for the sad face compared to the control. However, responses to the blue-sad pair were significantly faster than the red-sad pair. In the color-emostroop task, we observed a significant interaction between color and emotion target words in the modified emostroop task. Participants detected sad targets more accurately and faster in blue than red, but only in the incongruent condition. The results indicate that the influence of color in the processing of emotional information exists at the semantic level but found no evidence supporting the lexical level effect.

Color Affects Recognition of Emoticon Expressions

In computer-mediated communication, emoticons are conventionally rendered in yellow. Previous studies demonstrated that colors evoke certain affective meanings, and face color modulates perceived emotion. We investigated whether color variation affects the recognition of emoticon expressions. Japanese participants were presented with emoticons depicting four basic emotions (Happy, Sad, Angry, Surprised) and a Neutral expression, each rendered in eight colors. Four conditions (E1–E4) were employed in the lab-based experiment; E5, with an additional participant sample, was an online replication of the critical E4. In E1, colored emoticons were categorized in a 5AFC task. In E2–E5, stimulus affective meaning was assessed using visual scales with anchors corresponding to each emotion. The conditions varied in stimulus arrays: E2: light gray emoticons; E3: colored circles; E4 and E5: colored emoticons. The affective meaning of Angry and Sad emoticons was found to be stronger when conferred in warm and cool colors, respectively, the pattern highly consistent between E4 and E5. The affective meaning of colored emoticons is regressed to that of achromatic expression counterparts and decontextualized color. The findings provide evidence that affective congruency of the emoticon expression and the color it is rendered in facilitates recognition of the depicted emotion, augmenting the conveyed emotional message.

Facial coloration influences social approach-avoidance through social perception

Perceptions of others' social characteristics are essential for guiding social behaviour and decision making. Recent research has demonstrated that increased facial redness facilitates both positive (e.g. health, attractiveness, happiness) and negative (e.g. dominance, anger) social evaluations. Given that similar facial colouration can lead to diverging evaluations, it is unclear how people integrate these cues to inform social decisions (e.g. approach-avoidance). We suggest that the influence of facial redness on social perceptions and decisions depends on contextual information, including facial-muscular emotion expressions. We test this hypothesis across two studies where participants view faces either increasing or decreasing redness, evaluate them on a range of social characteristics (i.e. aggressiveness, attractiveness, health, friendliness, dominance) and decide whether to approach or avoid them. Increased facial redness facilitated, and decreased redness impeded (to a greater extent), perceptions of each social characteristic. However, the extent of this influence was moderated by the muscular expression (i.e. neutral, happy, angry). Further, we found that the influence of facial redness on approach-avoidance was largely mediated by evaluations of attractiveness and health. Altogether, the current work provides nuanced insights into facial colouration's role as a social signal that informs social perception and decision making.

Influence of Color on Emotion Recognition Is Not Bidirectional: An Investigation of the Association Between Color and Emotion Using a Stroop-Like Task

The association between color and emotion has been shown, with red facilitating recognition of anger and green facilitating recognition of happiness. However, it has been unclear if emotional stimulus conversely facilitates and/or inhibits recognition of such colors. This study used a Stroop-like task, which required participants to ignore facial expressions and recognize color, in order to investigate the influence of emotion on recognition of color. In addition, this study investigated the association between color and emotion recognition from emoticons, as it was recently suggested that the process of emotion recognition from emoticons was different from that of actual faces. Results revealed that for facial expressions and emoticons, color influenced emotion recognition, in line with previous studies. Conversely, facial expression did not influence recognition of color. The results suggest that in emotion recognition people consider surrounding contextual information and integrate it automatically; however, in color recognition, they do not.

Desaturation-Induced Brightness in Face Color Perception

The distinctiveness of perception of face from nonface objects has been noted previously. However, face brightness is often confounded with whiteness in the beauty industry; few studies have examined these perceptual differences. To investigate the interactions among face color attributes, we measured the effect of saturation on brightness and whiteness in both uniform color patches and face images to elucidate the relationship between these two perceptions. We found that, at constant luminance, a uniform color patch looked brighter with an increase in saturation (i.e., the Helmholtz-Kohlrausch effect occurred), while in contrast, brightness of a facial skin image looked less bright with increased saturation (i.e., contrary to the Helmholtz-Kohlrausch effect), which suggested this interaction of color attributes was influenced by top-down information. We conclude that this inverse effect of saturation on brightness for face images is not due to face recognition, color range of the skin tone, the luminance distribution, or recognition of human skin but due to the composite interactions of these facial skin factors in higher order recognition mechanisms.

Red color facilitates the detection of facial anger - But how much?

The color red seems to be consistently associated with the concept of anger. Beyond semantic associations, it has been suggested that the color red enhances our ability to perceive anger in faces. However, previous studies often lack proper color control or the results are confounded by the presence of several emotions. Moreover, the magnitude of the (potential) effect of red has not been quantified. To address these caveats, we quantified the effect of facial color and background color on anger with psychometric functions measured with the method-of-constant-stimuli while facial hue or surround hue was varied in CIELAB color space. Stimulus sequences were generated by morphing between neutral and angry faces. For the facial color, the average chromaticity of the faces was shifted by ΔE 12/20 in red, yellow, green and blue directions. For the background color, the hue was either neutral or saturated red, green or blue. Both facial redness and surround redness enhanced perceived anger slightly, by 3–4 morph-%. Other colors did not affect perceived anger. As the magnitude of the enhancement is generally small and the effect is robust only in a small subset of the participants, we question the practical significance of red in anger recognition.