Spatial reconstruction of human motion by means of a single camera and a biomechanical model

The value of the results of the inverse dynamic analysis procedures used in the study of human tasks is dependent on the quality of the kinematic and kinetic data supplied to the biomechanical model that supports it. The kinematic data, containing the position, velocity and acceleration of all anatomical segments of the biomechanical model, result from the reconstruction of human spatial motion by means of the evaluation of the anatomic points positions that enable to uniquely define the position of all anatomical segments. Furthermore, the motion data must be kinematically consistent with the structure of the biomechanical model used in the analysis. The traditional photogrammetric methodologies used for the spatial reconstruction of the human motion require images of two or more calibrated and synchronized cameras. This is due to the fact that the projection of each anatomical point is described by two linear equations relating its three spatial coordinates with the two coordinates of the projected point. The need for the image of another camera arises from the fact that a third equation is necessary to find the original spatial position of the anatomical point. The methodology proposed here substitutes the projection equations of the second camera with the kinematic constraint equations associated with a biomechanical model in the motion reconstruction process. In the formulation the system of equations arising from the point projections and biomechanical model kinematic constraints, representing the constant length of the anatomical segments, are solved simultaneously. Because the system of equations has multiple solutions for each image, a strategy based on the minimization of a cost function associated to the smoothness of the reconstructed motion is devised. It is shown how the process is implemented computationally avoiding any operator intervention during the motion reconstruction for a given time period. This leads to an automated computer procedure that ensures the uniqueness of the reconstructed motion. The result of the reconstruction process is a set of data that is kinematically consistent with the biomechanical model used. Through applications of the proposed methodology to several sports exercises its benefits and shortcomings are discussed.     

The Acceptance of Cosmetic Surgery Scale: initial examination of its factor structure and correlates among Brazilian adults

The present study conducted a preliminary examination of the psychometric properties of a recently developed Portuguese translation of the Acceptance of Cosmetic Surgery Scale (ACSS; Henderson-King & Henderson-King, 2005). A total of 311 Brazilian adults completed the ACSS along with Portuguese translations of measures of actual-ideal body weight discrepancy, body appreciation, sociocultural attitudes toward appearance, and demographics. Results showed that the Portuguese ACSS reduced to a three-factor solution consisting of the Intrapersonal, Social, and Consider factors uncovered in the original work using the ACSS. Moreover, there were only small sex differences on these subscales. In addition, the Portuguese ACSS showed a good pattern of convergent validity. The availability of the Portuguese ACSS is expected to stimulate more in-depth, quantitative research on attitudes toward cosmetic surgery within the Brazilian context.     

Data‐driven Methods for Modeling Social Perception

How do we model the complexity of social perception? A major methodological problem is that the space of possible variables driving social perceptions is infinitely large, thus posing an insurmountable hurdle for conventional approaches. Here, we describe a set of data‐driven methods whose objective is to identify quantitative relationships between high‐dimensional variables (e.g., visual images) and behaviors (e.g., perceptual decisions) with as little bias as possible. We focus on social perception of faces, although the methods could be applied to other visual and nonvisual categories. We review two reverse correlation approaches: (a) psychophysical methods based on judgments of images altered with randomly generated noise, where the analysis relates the random variations of the images to judgments; and (b) methods based on judgments of randomly generated faces from a statistical, multidimensional face space model, where the analysis relates the dimensions of the face model to judgments.     

Illusory conjunctions reflect the time course of the attentional blink

Illusory conjunctions in the time domain are binding errors for features from stimuli presented sequentially but in the same spatial position. A similar experimental paradigm is employed for the attentional blink (AB), an impairment of performance for the second of two targets when it is presented 200–500 msec after the first target. The analysis of errors along the time course of the AB allows the testing of models of illusory conjunctions. In an experiment, observers identified one (control condition) or two (experimental condition) letters in a specified color, so that illusory conjunctions in each response could be linked to specific positions in the series. Two items in the target colors (red and white, embedded in distractors of different colors) were employed in four conditions defined according to whether both targets were in the same or different colors. Besides the U-shaped function for hits, the errors were analyzed by calculating several response parameters reflecting characteristics such as the average position of the responses or the attentional suppression during the blink. The several error parameters cluster in two time courses, as would be expected from prevailing models of the AB. Furthermore, the results match the predictions from Botella, Barriopedro, and Suero’s (Journal of Experimental Psychology: Human Perception and Performance, 27, 1452–1467, 2001) model for illusory conjunctions.     

Prevalence and psychosocial risk factors associated with internet addiction in a nationally representative sample of college students in Taiwan

The aim of this study was to examine the prevalence of Internet addiction in a nationally representative sample of college students and to identify any associated psychosocial risk factors. The present study was constructed using a cross-sectional design with 3,616 participants. Participants were surveyed during the middle of the spring and fall semesters and recruited from colleges around Taiwan using stratified and cluster random sampling methods. Associations between Internet addiction and psychosocial risk factors were examined using stepwise logistic regression analysis. The prevalence of Internet addiction was found to be 15.3 percent (95 percent confidence interval, 14.1 percent to 16.5 percent). More depressive symptoms, higher positive outcome expectancy of Internet use, higher Internet usage time, lower refusal self-efficacy of Internet use, higher impulsivity, lower satisfaction with academic performance, being male, and insecure attachment style were positively correlated with Internet addiction. The prevalence of Internet addiction among college students in Taiwan was high, and the variables mentioned were independently predictive in the logistic regression analysis. This study can be used as a reference for policy making regarding the design of Internet addiction prevention programs and can also aid in the development of strategies designed to help Internet-addicted college students.     

A place for nouns and a place for verbs? A critical review of neurocognitive data on grammatical-class effects

It is generally held that noun processing is specifically sub-served by temporal areas, while the neural underpinnings of verb processing are located in the frontal lobe. However, this view is now challenged by a significant body of evidence accumulated over the years. Moreover, the results obtained so far on the neural implementation of noun and verb processing appear to be quite inconsistent. The present review briefly describes and critically re-considers the anatomo-correlative, neuroimaging, MEG, TMS and cortical stimulation studies on nouns and verbs with the aim of assessing the consistency of their results, particularly within techniques. The paper also addresses the question as to whether the inconsistency of the data could be due to the variety of the tasks used. However, it emerged that neither the different investigation techniques used nor the different cognitive tasks employed fully explain the variability of the data. In the final section we thus suggest that the main reason for the emergence of inconsistent data in this field is that the cerebral circuits underlying noun and verb processing are not spatially segregated, at least for the spatial resolution currently used in most neuroimaging studies.     

Effects of long-term blindness on preparatory emg modulation in humans performing landing movements

To investigate the long-term effect of blindness on the task of leaping down to a lower landing surface, five blind individuals were compared with 10 sighted individuals who performed landing movements with and without sight. Participants performed six consecutive drop-landings from four different heights, during which the prelanding modulation of EMG timing and amplitude in four lower-limb muscles were recorded. Analysis showed that blind individuals showed specific prelanding EMG modulation, suggesting that long-term dependence on somesthetic and vestibular cues leads to different preparatory measures for vertical falls.     

Positive emotions, emotional intelligence, and successful experiential learning

This study explored the role that positive emotions and emotional intelligence play in experiential learning. Students’ field practicum journals were analyzed using the Linguistic Inquiry and Word Count Program (LIWC) and a measure of emotional intelligence was obtained using the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). Positive emotion words were robustly associated with almost all dimensions of supervisors’ ratings of students’ performance, but showed weak associations with students’ ratings of perceived benefits associated with their practicum experiences. Overall EI scores were correlated with several of the supervisor rating items and the Facilitating Thought and Managing Emotions subscales of the EI were robustly correlated with many of the student rating items. This study thus yielded a more differentiated view of the role of positive emotions and emotional intelligence in adaptive functioning and underscored the importance of using multiple informants to assess a complex construct such as successful experiential learning.     

Achievement goals, social goals, and motivational regulations in physical education settings

This study examined the relationship between achievement and social goals, and explored how both goals affect students' level of informed self-determination in Physical Education. Participants were 395 high school students. Three scales were used to assess achievement, social goals, and motivation. Several hierarchical regression analyses revealed that mastery-approach goals were the greatest contributors to the individuals' levels of self-determination. Achievement and social goals were found to be separate predictors of students' levels of self-determination, and this highlights the importance of separating mastery and performance goals into avoidance and approach profiles. Girls reported significantly higher values than boys on responsibility, relationship, and mastery-avoidance goals, whereas boys scored higher on performance-approach goals. Researchers could use achievement and social goals to study students' motivation and achievement in Physical Education settings.