Mouth Curvature Research Articles

The effect of sleep deprivation on objective and subjective measures of facial appearance.

The faces of people who are sleep deprived are perceived by others as looking paler, less healthy and less attractive compared to when well rested. However, there is little research using objective measures to investigate sleep-loss-related changes in facial appearance. We aimed to assess the effects of sleep deprivation on skin colour, eye openness, mouth curvature and periorbital darkness using objective measures, as well as to replicate previous findings for subjective ratings. We also investigated the extent to which these facial features predicted ratings of fatigue by others and could be used to classify the sleep condition of the person. Subjects (n=181) were randomised to one night of total sleep deprivation or a night of normal sleep (8-9hr in bed). The following day facial photographs were taken and, in a subset (n=141), skin colour was measured using spectrophotometry. A separate set of participants (n=63) later rated the photographs in terms of health, paleness and fatigue. The photographs were also digitally analysed with respect to eye openness, mouth curvature and periorbital darkness. The results showed that neither sleep deprivation nor the subjects' sleepiness was related to differences in any facial variable. Similarly, there was no difference in subjective ratings between the groups. Decreased skin yellowness, less eye openness, downward mouth curvature and periorbital darkness all predicted increased fatigue ratings by others. However, the combination of appearance variables could not be accurately used to classify sleep condition. These findings have implications for both face-to-face and computerised visual assessment of sleep loss and fatigue.

Assessing the accuracy of perceptions of intelligence based on heritable facial features

Perceptions of intelligence based on facial features can have a profound impact on many social situations, but findings have been mixed as to whether these judgements are accurate. Even if such perceptions were accurate, the underlying mechanism is unclear. Several possibilities have been proposed, including evolutionary explanations where certain morphological facial features are associated with fitness-related traits (including cognitive development), or that intelligence judgements are over-generalisation of cues of transitory states that can influence cognition (e.g., tiredness). Here, we attempt to identify the morphological signals that individuals use to make intelligence judgements from facial photographs. In a genetically informative sample of 1660 twins and their siblings, we measured IQ and also perceptions of intelligence based on facial photographs. We found that intelligence judgements were associated with both stable morphological facial traits (face height, interpupillary distance, and nose size) and more transitory facial cues (eyelid openness, and mouth curvature). There was a significant association between perceived intelligence and measured IQ, but of the specific facial attributes only interpupillary distance (i.e., wide-set eyes) significantly mediated this relationship. We also found evidence that perceived intelligence and measured IQ share a familial component, though we could not distinguish between genetic and shared environmental sources.

Mona Lisa is always happy \u2013 and only sometimes sad

The worldwide fascination of da Vinci’s Mona Lisa has been dedicated to the emotional ambiguity of her face expression. In the present study we manipulated Mona Lisa’s mouth curvature as one potential source of ambiguity and studied how a range of happier and sadder face variants influences perception. In two experimental conditions we presented different stimulus ranges with different step sizes between stimuli along the happy-sad axis of emotional face expressions. Stimuli were presented in random order and participants indicated the perceived emotional face expression (first task) and the confidence of their response (second task). The probability of responding ‘happy’ to the original Mona Lisa was close to 100%. Furthermore, in both conditions the perceived happiness of Mona Lisa variants described sigmoidal functions of the mouth curvature. Participants’ confidence was weakest around the sigmoidal inflection points. Remarkably, the sigmoidal functions, as well as confidence values and reaction times, differed significantly between experimental conditions. Finally, participants responded generally faster to happy than to sad faces. Overall, the original Mona Lisa seems to be less ambiguous than expected. However, perception of and reaction to the emotional face content is relative and strongly depends on the used stimulus range.

Eyelid-openness and mouth curvature influence perceived intelligence beyond attractiveness.

Impression formation is profoundly influenced by facial attractiveness, but the existence of facial cues which affect judgments beyond such an "attractiveness halo" may be underestimated. Because depression and tiredness adversely affect cognitive capacity, we reasoned that facial cues to mood (mouth curvature) and alertness (eyelid-openness) affect impressions of intellectual capacity. Over 4 studies we investigated the influence of these malleable facial cues on first impressions of intelligence. In Studies 1 and 2 we scrutinize the perceived intelligence and attractiveness ratings of images of 100 adults (aged 18-33) and 90 school-age children (aged 5-17), respectively. Intelligence impression was partially mediated by attractiveness, but independent effects of eyelid-openness and subtle smiling were found that enhanced intelligence ratings independent of attractiveness. In Study 3 we digitally manipulated stimuli to have altered eyelid-openness or mouth curvature and found that each independent manipulation had an influence on perceptions of intelligence. In a final set of stimuli (Study 4) we explored changes in these cues before and after sleep restriction, to examine whether natural variations in these cues according to sleep condition can influence perceptions. In Studies 3 and 4 variations with increased eyelid-openness and mouth curvature were found to relate positively to intelligence ratings. These findings suggest potential overgeneralizations based on subtle facial cues that indicate mood and tiredness, both of which alter cognitive ability. These findings also have important implications for students who are directly influenced by expectations of ability and teachers who may form expectations based on initial perceptions of intelligence.

Processing Facial Expressions of Emotion: Upright vs. Inverted Images

We studied discrimination of briefly presented upright vs. inverted emotional facial expressions (FEs), hypothesizing that inversion would impair emotion decoding by disrupting holistic FE processing. Stimuli were photographs of seven emotion prototypes, of a male and female poser (Ekman and Friesen, 1976), and eight intermediate morphs in each set. Subjects made speeded Same/Different judgments of emotional content for all upright (U) or inverted (I) pairs of FEs, presented for 500 ms, 100 times each pair. Signal Detection Theory revealed the sensitivity measure d′ to be slightly but significantly higher for the upright FEs. In further analysis using multidimensional scaling (MDS), percentages of Same judgments were taken as an index of pairwise perceptual similarity, separately for U and I presentation mode. The outcome was a 4D “emotion expression space,” with FEs represented as points and the dimensions identified as Happy–Sad, Surprise/Fear, Disgust, and Anger. The solutions for U and I FEs were compared by means of cophenetic and canonical correlation, Procrustes analysis, and weighted-Euclidean analysis of individual differences. Differences in discrimination produced by inverting FE stimuli were found to be small and manifested as minor changes in the MDS structure or weights of the dimensions. Solutions differed substantially more between the two posers, however. Notably, for stimuli containing elements of Happiness (whether U or I), the MDS structure showed signs of implicit categorization, indicating that mouth curvature – the dominant feature conveying Happiness – is visually salient and receives early processing. The findings suggest that for briefly presented FEs, Same/Different decisions are dominated by low-level visual analysis of abstract patterns of lightness and edge filters, but also reflect emerging featural analysis. These analyses, insensitive to face orientation, enable initial positive/negative Valence categorization of FEs.

Can the same Visual Modality Express Arousal or Valence Depending on the other Modalities it is Combined with?

The work described in this paper explores if the same visual modality (sharpness of curvature) can be used to express different dimensions of emotions (arousal and valence) depending on the modalities it is combined with. We propose two novel approaches to visually express emotions in affective agents. Both models employ a simplistic character consisting of an abstract body modelled as a closed sequence of concatenated curves. Emotions are represented in terms of arousal and valence dimensions. In the first model, the arousal value is expressed through the sharpness of the curves that comprise the character outline, while the valence value is expressed through the curvature of the character's mouth. In the second model, the arousal value is expressed through the character's movement, while the valence value is expressed through the sharpness of the curves that comprise the character outline. Thus, sharpness of curvature is used to express arousal in the first model and valence in the second one. The paper also describes a user experiment which investigated whether the arousal and valence expressed by our models are appropriately perceived by the users or not. The results support both models and suggest that sharpness of curvature could be used to express arousal or valence if consistently combined with other appropriate modalities.

A New Faces Scale in Pain Measurement: A Test of Bias From Current Mood, Trait Affectivity, and Scale Range

Faces pain rating scales used among children have been criticized to confound affective states with pain when smiling faces are included. This experimental study is an attempt to examine the possible confounding of affective states with pain when smiling faces are used as part of a faces scale. The meaning of the faces was tested to depend on current mood, current pain, trait affectivity, and inclusion versus exclusion of smiling faces. Sixty-four participants made 6,720 two-categorical pain judgments on faces with different mouth curvature. In multilevel regression analysis, current level of pain and negative trait affectivity biased faces' meaning only when the smiling faces were excluded from the scale. In adults, the new full range faces pain scale including a midpoint neutral face and smiling faces was more robust than the restricted scale. The faces scale that was tested in this study is not applicable for patient measurement but it is an interesting tool for psychological research.

Not just another face in the crowd: Detecting emotional schematic faces during continuous flash suppression.

To test whether threatening visual information receives prioritized processing, many studies have examined visual search for emotional schematic faces. Still, it has remained unclear whether negative or positive schematic faces are processed more efficiently. We used continuous flash suppression, a variant of binocular rivalry, to render single emotional schematic faces invisible and measured whether negative or positive faces have an advantage in accessing awareness. Across three experiments, positive faces were detected more quickly than negative faces. A fourth experiment indicated that this positive face advantage was unrelated to the valence of the face stimuli but due to the relative orientation of the mouth curvature and the face contour. These findings demonstrate the impact of configural stimulus properties on perceptual suppression during binocular rivalry and point to a perceptual confound present in emotional schematic faces that might account for some ambiguous results obtained with schematic face stimuli in previous studies.

Minimalist approach to show emotions via a flock of smileys

This paper proposes and explores an approach to express emotions which intends to minimize the user's expectations. The approach uses a flock of virtual beings where each virtual being is represented as a simple smiley. Emotions are represented in terms of the arousal and the valence dimensions and they are visually expressed in a simple way through the behaviour and appearance of the individuals in the flock. In particular, the arousal value parameterizes the flocking algorithm, and the valence value determines the curvature of the smileys’ mouth. Furthermore, the paper describes a user experiment which investigated whether the arousal and the valence expressed by our model are appropriately perceived by the users or not. The results suggest that combinations of movement and mouth curvature are perceived correctly as particular emotions, that movement and mouth curvature are perceived as arousal and valence respectively and that they are independent of each other. The experiment also compared our approach with both a state-of-the-art virtual character and a minimalist character in terms of user's expectations. The results suggest that the proposed model generates less expectations than the compared models.

Computer-Animated Faces Pain Scale: Commentary on Fanciullo et al. (2007)

The article by Fanciullo et al. [1], entitled “Development of a new computer method to assess children's pain,” raises many important issues regarding measurement and implementation problems associated with various self-report faces scales designed to assess pain in children. The authors introduce a computer-based faces scale that enables children to rate their pain on a continuous scale by adjusting the facial expression (shape of mouth and eyes) to indicate their pain intensity. We agree with the authors' statements concerning the potential advantages of a computer-based, continuous faces scale, namely sensitivity, patient preference, and computer data acquisition and display. Our experience with such a scale developed in 1997 [2–4] largely supports these assertions. The authors emphasized a presumed direct correspondence between pain intensity and the amount of curvature of the mouth and diameter of the eyes. However, in doing so, they seem to have ignored a basic rule of psychophysics. They assumed that physically equal changes (intervals) in facial expression are perceptually equal intervals. If that were the case, then Mona Lisa's smile would be nothing special. Subtle changes in …

Wide eyes and an open mouth enhance facial threat

Two rating experiments were conducted to examine the effect of opening the mouth and widening the eyes on ratings of facial threat. In Experiment 1, 65 participants rated faces for threat, arousal and valence (pleasantness). The faces varied in eyebrow shape (V-shaped, flat), mouth type (closed, open), eye type (wide, normal) and mouth curvature (down-turned, up-turned). In replication of previous research (Lundqvist, Esteves, & Öhman, 1999, 2004), the V-shaped eyebrow was the most important determinant of facial threat. Faces with a V-shaped eyebrow were rated as more aroused and threatening, and less pleasant than faces with a flat eyebrow. Similar, albeit weaker, effects were recorded for mouth and eye type, leading to a new hierarchical ordering of facial features for determining facial threat (eyebrow type > mouth type > eye type > mouth curvature). In Experiment 2 (n=37) the effects and ordering recorded in Experiment 1 were replicated for ratings of face of a woman and, moreover , individual features (except an up-turned mouth) increased ratings of threat compared to an expressionless control condition.

Dynamic Interactive Aesthetics

In this paper, I independently build on an earlier collaborative effort with Dr. Cynthia Breazeal (MIT Media Lab) to integrate social and cultural theory and applied graphic design theory and practice into the participatory design process of a socially intelligent robot prototype called Kismet. My objective is to explore the feasibility of facilitating audience interaction in the graphic design process of this robot prototype-”potentially a mass-produced consumer product-”through the appropriation of a simple, communication convention: an email message. Steinhauer's (2000) Interactive Aesthetics (IA) is applied with the creation and distribution of an electronic survey that informs the target mass audience of an interdisciplinary design project underway and canvasses responses from the members of the mass audience regarding the aesthetic design of Kismet the robot prototype. The empirical results this paper reports supports the author's hypothesis that graphic design conventions, techniques, and strategies can facilitate interaction between the target mass audience (especially the global mass audience) and other professional participants in a participatory design process. However, further analysis of these results uncovers a need for a differentiation between static and dynamic communication artifacts. While Interactive Aesthetics works for static two-dimensional communication artifacts, an integration of a more dynamic interactivity is necessary in a participatory design process that involves a communication artifact like a three-dimensional robot prototype, which has the ability to display non-verbal communication-”fluid emotive facial expressions-”when it communicates with another human being in a given public space. Most communication frameworks assume that emotional expression should be understood in terms of the exchange of socially assigned static symbols. While written or spoken linguistic communication is indeed accurately portrayed as a series of physically arbitrary, static symbols, much emotional expression (such as paralinguistic intonation in speech, expressive facial dynamics, emphatic gesture, etc.) is better described as analog representation. That is, rather than encoding information in physically arbitrary, static symbols, analog representation embeds information in a physical dynamic which is structurally analogous to the information it represents. What is the implication for the participatory design process? Whether mere images on a screen (e.g. an avatar) or a full-scale socially intelligent robot (e.g. Kismet), the aesthetic design of a dynamic form requires simulations through analog parameters. Dynamic Interactive Aesthetics is a term introduced here to describe the facilitation of audience input through simulated analog parameters to achieve the aesthetic design of a dynamic communication artifact. By adopting Dynamic Interactive Aesthetics, I can elicit feedback from the target audience that becomes the basis for determining the 'form and function' of a dynamic design. Audience input regarding the design for a dynamic, affective prototype based on analog simulation is better able to respond to the audience's aesthetic preferences. The critical vernacular that creative design professionals use to modify and edit static symbols that represent information becomes simplified for the target audience through the use of conventional, user-friendly control devices that modify simulated analog parameters. As a result, the vernacular of applied design criticism that includes the application of varying aesthetic treatments to static symbols needs to be mathematically translated into digital signals with continuous intensities of measurable aesthetic properties. By allowing the target audience to directly modify these analog parameters (e.g. the ratio between simulated mouth curvature and a simulated happiness parameter) the target user(s) can generate a customer-specific (or culture-specific) affective interface. By offering users a series of such expressive parameters, professional designers can collaborate with a target audience to create an affective synthetic interface that responds to a wide variety of aesthetic and functional needs.

The Use of Faces to Represent Points in k-Dimensional Space Graphically

Abstract A novel method of representing multivariate data is presented. Each point in k-dimensional space, k≤18, is represented by a cartoon of a face whose features, such as length of nose and curvature of mouth, correspond to components of the point. Thus every multivariate observation is visualized as a computer-drawn face. This presentation makes it easy for the human mind to grasp many of the essential regularities and irregularities present in the data. Other graphical representations are described briefly.

The Use of Faces to Represent Points in K-Dimensional Space Graphically

Abstract A novel method of representing multivariate data is presented. Each point in k-dimensional space, k≤18, is represented by a cartoon of a face whose features, such as length of nose and curvature of mouth, correspond to components of the point. Thus every multivariate observation is visualized as a computer-drawn face. This presentation makes it easy for the human mind to grasp many of the essential regularities and irregularities present in the data. Other graphical representations are described briefly.