We constantly perceive and categorize internal signals, like our subjective affective state, and complex social signals, like the faces of the people around us. In this dissertation, I aim to characterize some of the ways in which we perceive and categorize affective and social stimuli, top-down influences on those processes, and individual differences in social & affective perception/categorization. First, in Chapter 2, I apply psychophysical methods to assess how individual differences in trait emotional expressivity arise from observers' subjective emotion reporting thresholds. Next, in Chapter 3, I characterize the perception and categorization of age from adult faces. Finally, in Chapter 4, I investigate whether the act of categorizing one's subjective emotional state changes the affective distance between neural representations of positive and negative affect states.

This study examines print advertising from Cookie, an up-scale American parenting magazine for affluent mothers. The ads include seven designer clothing brands: Rocawear, Baby Phat, Ralph Lauren, Diesel, Kenneth Cole, Sean John, and DKNY. When considered within the context of their adult equivalents, the ads for the children’s lines often created a prolepsis—or flash-forward—by depicting the child model as a nascent adult. This was accomplished in three ways. First, the children’s ads typically contained structural continuities such as logo, set design, and color scheme that helped reinforce their relationship with the adult brand. Second, most of the ads place the camera at eye-level—a framing that allows the child models to address their adult viewers as equals. Finally, almost half of the ads feature at least one child looking directly at the camera with a serious expression. This is significant because, in Western culture, the withholding of a smile is a sign of dominance typically reserved for adult males. When children mimic this familiar and powerful “look,” they convey a sense of adult-like confidence and self-awareness often associated with precocious sexuality.

Human faces provide a rich source of behavioral data. Following acute, potentially traumatic events, manual and automated coding systems of facial behavior may help identify individuals at risk for developing psychopathology. In the present study, OpenFace, an automated system, and FACS, a manual method, were compared as predictors of long-term functioning using facial behavioral data from clinical interviews collected one-month after a potentially traumatic event that brought participants into the emergency department of a Level-1 Trauma Center in New York City. We evaluated similarities and differences in facial emotions identified by FACS and OpenFace to determine their predictive accuracy in capturing Depression and PTSD 6-months and 12-months later. The findings suggest OpenFace is a more sensitive and precise measure of facial behavior than FACS.

Facial expressions play a large role in non verbal communication. Research shows promising results for using games to improve facial expression recognition in children with autism spectrum disorder. Games are effective educational tools and are successful in motivating students. Using a game to improve facial expression recognition could be beneficial for all children as it reduces the risk for problematic behavior and mental health issues. For this study a game to train facial expression recognition to children was developed and evaluated. The goal of the evaluation was to determine which factors influence performance and engagement in the game and if there are expressions that are often identified incorrectly. Additionally the children’s attitude towards the game was evaluated. The results show that performance is affected by the difficulty, context and intensity. The children that showed the most engagement also performed better in the beginning of the game, however the correlation between performance and engagement is complex. Unfortunately it was not possible to evaluate the effect of rewards on the children’s engagement, but children were generally positive on the rewards. The confusion of expressions was in line with earlier research, but not as symmetrical. The players were generally positive about the game. Further research is needed to determine the long term learning effects of the game and to assess ways to engage players more. / Ansiktsuttryck utgör en stor del av den icke-verbala kommunikationen vid sociala interaktioner. Forskning visar lovande resultat för att använda spel för att förbättra förmågan att identifiera ansiktsuttryck för barn med autismspektrumtillstånd. Spel är effektiva utbildningsverktyg och framgångsrika att motivera studenter. Att använda spel för att förbättra denna förmåga skulle kunna vara fördelaktigt för alla barn eftersom det minskar risken för problembeteenden och psykisk ohölsa. Syftet med denna studie var att utveckla och utvärdera ett spel för barn för att träna förmågan att identifiera ansiktsuttryck. Målet med utvärderingen var att avgöra vilka faktorer som påverkar prestation och engagemang i spelet samt huruvida det finns uttryck som ofta identifieras inkorrekt. Ett ytterligare mål var att utvärdera barnens åsikter om spelet. 54 barn i åldrarna 8 och 11 år testade spelet vid två tillfällen. Resultatet visar att prestation påverkas av svårighetsgrad, kontext samt intensitet. De barn som visade högst engagemang presterade även bättre inledningsvis än övriga, dock återfanns inget linjärt samband mellan prestation och engagemang. Tyvärr var det inte möjligt att utvärdera hur belöningarna i spelet påverkade engagemanget, däremot uttryckte barnen sig positivt om dem. Förvirringen kring uttryck var i linje med tidigare forskning, dock mindre symmetrisk. Spelarna uttryckte generellt positiva åsikter om spelet. Vidare forskning behövs för att avgöra spelets långsiktiga inlärningseffekter samt för att undersöka sätt att påverka spelarnas engagemang.

Deaf sign language users oftentimes claim to be able to recognise straight away whether their interlocutors are native signers. To date it is unclear, however, what exactly such judgement calls might be based on. The aim of the research presented was to explore whether specific articulatory features are being associated with signers that have (allegedly) acquired German Sign Language (Deutsche Gebärdensprache, DGS) as their first language. The study is based on the analysis of qualitative and quantitative data. Qualitative data were generated in ten focus group settings. Each group was made up of three participants and one facilitator. Deaf participants’ meta-linguistic claims concerning linguistic features of ‘native signing’ (i.e. what native signing looks like) were qualitatively analysed using grounded theory methods. Quantitative data were generated via a language assessment experiment designed around stimulus material extracted from DGS corpus data. Participants were asked to judge whether or not individual clips extracted from a DGS corpus had been produced by a native signer. Against the backdrop of the findings identified in the focus group data, the stimulus material was subsequently linguistically analysed in order toidentify specificlinguistic features that might account for some clips to be judged as ‘produced by a native signer’ as opposed to others that were claimed to have been ‘articulated by a non-native signer’. Through juxtaposing meta-linguistic perspectives, the results of a language perception experiment and the linguistic analysis of the stimulus material, the study brings to the fore specific crystallisation points of linguistic and social features indexing linguistic authenticity. The findings break new ground in that they suggest that the face as articulator in general, and micro-prosodic features expressed in the movement of eyes, eyebrows and mouth in particular, play a significant role in the perception of others as (non-)native signers.

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<p>Older adults tend to show overall recognition deficits and qualitatively different patterns in the particular expressions that are most difficult to identify (Ruffman et al., 2008). In the current study, 23 younger (18-33 years old) and 23 older (60-80 years old) adults performed a 4AFC (angry, fearful, happy, sad) facial expression categorization task varying orientation (upright/inverted) and stimulus duration (100, 500, 1000 ms). For both groups, happiness was the easiest expression to identify and fear and sadness were the most difficult. Compared to younger adults, older adults were more affected by stimulus orientation, and generally benefit less from increased stimulus duration. For upright faces, there was no age difference in response accuracy but response latency was longer in older subjects. For inverted faces, older adults showed lower accuracy and longer latencies for expressions of anger, fear, and sadness. Recognition of inverted happy faces was spared in older adults for accuracy, but not response latency. These findings could not be explained by impaired detection sensitivity, as no systematic age differences were found for perceived intensity ratings. Finally, the expressions that were most to least difficult to identify was the same in each age group at both orientations. Overall, these results suggest that older individuals process expressive faces in a qualitatively similar way to their younger counterparts, but are less efficient at extracting the diagnostic information.</p> / Master of Science (MSc)

Mimicking facial structures for a robotic head requires integration of multiple structural and mechanical parameters, design, synthesis and control of muscle actuation, architecture of the linkages between actuation points within skin, and implementation of the deformation matrix with respect to global skull coordinates. In this dissertation, humanoid faces were designed and fabricated to investigate all the parameters mentioned above. A prototype face and neck was developed using servo motors and extensively characterized. In this prototype, a neck mechanism was designed using a four bar mechanism to achieve nodding and turning motions. The modular neck prototype simplifies the assembly and statically in equilibrium and hence demands less torque from the cost-effective RC servo motor. The mechanism was critically investigated for dynamic performance and it was found out that RC servo based robotic head requires a PD external controller to overcome inherent overshoot. The servo based robotic head was analyzed for design and control of anchor, architecture of linkages between actuation points within skin, and deformation matrix with respect to global coordinate for creating specific expressions. A functional relationship between deformation vector of facial control points and actuator parameter, skin elasticity and angular position of actuator was derived. The developed analysis method is applicable to any rotary actuator technology utilized for facial expressions and takes into account the skin stiffness. The artificial skin materials for facial expression were synthesized using platinum-cured silicone elastomeric material (Reynolds Advanced Materials Inc.) with base consisting of mainly polyorganosiloxanes, amorphous silica and platinum-siloxane complex compounds. Systematic incorporation of porosity in this material was found to lower the force required to deform the skin in the axial direction. The performance of the servo motor based face was quite realistic but it suffers from the drawback of large power consumption, bulky, heavy, and limited functionality. Thus, significant effort was made in developing a Biometal fiber and Flexinol shape memory alloy actuator (SMA) based biped mountable baby head facial structure which resembles the form and functionality of a human being. SMAs were embedded inside a skull and connected to elastomeric skin at control points. An engineered architecture of skull was fabricated that incorporates all the muscles with their 35 routine pulleys, two fire wire CMOS cameras that serve as eyes, and a battery powered microcontroller base driving circuit within the total dimensions of 140 mm x 90 mm x 110 mm. The driving circuit was designed such that it can be easily integrated with biped and processed in real-time. The humanoid face with 12DOF was mounted on the body of DARwIn (Dynamic Anthropomorphic Robot with Intelligence) robot which has 21 DOF resulting in a total of 33 DOF system. Characterization results on the face and associated design issues are described that provide pathways for developing human-like facial anatomy. Numerical simulation using Simulink was conducted to assess the performance of a prototypic robotic face mainly focusing on jaw movement. A graphical method “Graphical Facial Expression Analysis and Design (GFEAD)” was developed that can be used to allocate the sinking points on robotic head. The method assumes that the origin of the action units are known prior and the underlying criterion in the design of faces being deformation of a soft elastomeric skin through tension in anchoring wires attached on one end to the sinking point and on the other to the actuator. Experimental characterization on a prototyping humanoid face was performed to validate the model and demonstrate the applicability on a generic platform. During characterization of the SMA based face, it was found that the currently available artificial muscle technologies do not meet the entire requirement for being embedded in the skin and provide the required strain rate, maximum strain, blocking force, response time and energy density. Thus an effort was made to develop conducting polymer based artificial muscles which can meet the metrics of human muscle. Composite stripe and zigzag actuators consisting of a sandwich structure polypyrrole /poly(vinylidene difluoride) (PPy/PVDF) were synthesized using potentiodynamic film growth on gold electrodes. The synthesis was done from an aqueous solution containing tetrabutylammonium Perchlorate (TBAP) and pyrrole by polymerization at room temperature. For depositing thin PPy films and thereby minimizing the response time, an experimental optimization of the deposition conditions was performed. The number of current-potential (potentiodynamic) growth cycles and the thickness of the deposited PPy film were highly correlated in the initial stages of polymer film growth. Strip actuator of size 11 x 5 mm2 with 63μM exhibited a deflection of 3mm under 1V DC voltage and 2mm deflection under 8V AC voltage at 0.5 Hz. It was found that three-segment zigzag actuator of segment length 15x2.5mm and thickness 63μM amplifies the displacement by 1.5 times. A study was also conducted on the synthesis and characterization of thick and thin film polypyrrole (PPy) – metal composite actuators. The fabrication method consisted of three steps based upon the approach proposed by Ding et al.: (i) winding the conductive spiral structure around the platinum (Pt)-wire core, (ii) deposition of PPy film on the Pt-wire core, and (iii) removal of the Pt-wire core. This approach yielded good performance from the synthesized actuators, but was complex to implement due to the difficulty in implementing the third step. To overcome the problem of mechanical damage occurring during withdrawal of Pt-wire, the core was replaced with a dispensable gold coated polylactide fiber that could be dissolved at the end of deposition step. Experimental results indicate that thin film actuators perform better in terms of response time and blocking force. A unique muscle-like structure with smoothly varying cross-section was grown by combining layer by layer deposition with changes in position and orientation of the counter electrode in reference to the working electrode. Synthesis of polypyrrole–metal coil was conducted in aqueous solution containing 0.25 M Pyrrole, 0.10 M TBAP and 0.50 M KCl. The actuator consisted of a single layer of platinum winding on a core substrate. Electrochemical characterization for free strain and blocking stress was conducted 0.1 M TBAP solution and a 6% free strain was obtained at an applied potential of 6V DC after 80 s stimulation time. The blocking stress 18 kPa was estimated by extrapolating the strain magnitude on stress-strain diagram. For axial type actuator with coil winding, a generalized governing equation for the electrochemical stress generated from polypyrrole–metal coil which accommodates the effect of magnetic field due to winding was proposed and numerically studied. It was considered as insightful modeling. / Ph. D.

This experiment was designed to elucidate the function of adult facial and vocal behavior for infant perception and expression of affect. Nine infants were studied longitudinally at 2 months and at 3 1/2 months using a dynamic visual display that consisted of a videotape of a woman moving her face while expressing happiness or sadness. A second group of 10 infants were studied similarly ina version of this procedure that used a static videotaped display of the woman's face in which she showed fixed expressions of either emotion. Both types of visual displays were accompanied by a soundtrack playing either affectively matched or unmatched infant-directed (ID) speech. Infant visual fixations of the display area were determined during the experimental session by a trained observer who was kept unaware of the stimuli being presented. The sum of these fixations for infants in the Static condition was greater than that of infants in the Dynamic condition. A similar analysis of the average length of infants’ visual fixations revealed no significant results. Analyses of infant affect and "interactiveness" were also conducted by having trained raters score videotapes of each session using one of 4 rating scales. According to 2 of these measures, infant facial affect was more positive during displays that contained happy elements than during matched sad displays, and 3 1/2-month olds were more frequently rated as More Happy during matched happy displays. Thus, infants showed different affective responses to the 4 face-voice combinations, even though they did not attend differently to the displays. In addition, infant facial affect was more positive at 3 1/2 months because smiling at displays was more reliable at this age. The analysis of infant "interactiveness" revealed that 3 1/2-month olds in the Static condition were more "interactive" than those in the Dynamic condition. A supplementary analysis of a questionnaire that was designed to measure parents' perceptions of their infants showed that almost 1/5th of the attrition at 2 months could be accounted for by infants' tendencies to respond negatively to novel experiences. The results of this study are discussed in terms of their implications for future research in infant perception. / Ph. D.