Stick Figure Research Articles

Perceptual and computational analysis of critical features for biological motion

Among the most common events in our daily lives is seeing people in action. Scientists have accumulated evidence suggesting humans may have developed specialized mechanisms for recognizing these visual events. In the current experiments, we apply the "bubbles" technique to construct space-time classification movies that reveal the key features human observers use to discriminate biological motion stimuli (point-light and stick figure walkers). We find that observers rely on similar features for both types of stimuli, namely, form information in the upper body and dynamic information in the relative motion of the limbs. To measure the contributions of motion and form analyses in this task, we computed classification movies from the responses of a biologically plausible model that can discriminate biological motion patterns (M. A. Giese & T. Poggio, 2003). The model classification movies reveal similar key features to observers, with the model's motion and form pathways each capturing unique aspects of human performance. In a second experiment, we computed classification movies derived from trials of varying exposure times (67-267 ms) and demonstrate the transition to form-based strategies as motion information becomes less available. Overall, these results highlight the relative contributions of motion and form computations to biological motion perception.

Perceptual biases in biological motion perception and other depth-ambiguous stimuli

• Each subject ran 1000 trials • All walkers are stick figures • 20% of the displays show cubes, the rest walkers • Task: Is the figure rotating clockwise or counterclockwise? • For Necker cubes, we find a very pronounced viewing-from-above bias (Fig. 1a) • We see a reasonable facing-the-viewer bias, but it does not seem to depend on the gender of the walker (Fig. 1b) • Facing bias is stronger for dynamic than for static figures (Fig. 1c). • Masked by the facing bias, we still see a small viewing-from-above bias (Fig. 1d) • We see a substantial ccw bias for the stick figures (Fig. 1b-d) pr op or tio n cc w Example data (subj. MH)

Effect of Arrangement of Stick Figures on Estimates of Proportion in Risk Graphics

Health risks are sometimes illustrated with stick figures, with a certain proportion colored to indicate they are affected by the disease. Perception of these graphics may be affected by whether the affected stick figures are scattered randomly throughout the group or arranged in a block. . To assess the effects of stick-figure arrangement on first impressions of estimates of proportion, under a 10-s deadline. . Questionnaire. Participants and Setting. Respondents recruited online (n = 100) or in waiting rooms at an urban hospital (n = 65). Intervention. Participants were asked to estimate the proportion represented in 6 unlabeled graphics, half randomly arranged and half sequentially arranged. Measurements. Estimated proportions. . Although average estimates were fairly good, the variability of estimates was high. Overestimates of random graphics were larger than overestimates of sequential ones, except when the proportion was near 50%; variability was also higher with random graphics. Although the average inaccuracy was modest, it was large enough that more than one quarter of respondents confused 2 graphics depicting proportions that differed by 11 percentage points. Low numeracy and educational level were associated with inaccuracy. Limitations. Participants estimated proportions but did not report perceived risk. . Randomly arranged arrays of stick figures should be used with care because viewers' ability to estimate the proportion in these graphics is so poor that moderate differences between risks may not be visible. In addition, random arrangements may create an initial impression that proportions, especially large ones, are larger than they are.

Effects of game-like interactive graphics on risk perceptions and decisions.

Many patients have difficulty interpreting risks described in statistical terms as percentages. Computer game technology offers the opportunity to experience how often an event occurs, rather than simply read about its frequency. . To assess effects of interactive graphics on risk perceptions and decisions. . Electronic questionnaire. Participants and setting. Respondents (n = 165) recruited online or at an urban hospital. Intervention. Health risks were illustrated by either static graphics or interactive game-like graphics. The interactive search graphic was a grid of squares, which, when clicked, revealed stick figures underneath. Respondents had to click until they found a figure affected by the disease. Measurements. Risk feelings, risk estimates, intention to take preventive action. . Different graphics did not affect mean risk estimates, risk feelings, or intention. Low-numeracy participants reported significantly higher risk feelings than high-numeracy ones except with the interactive search graphic. Unexpectedly, respondents reported stronger intentions to take preventive action when the intention question followed questions about efficacy and disease severity than when it followed perceived risk questions (65% v. 34%; P < 0.001). When respondents reported risk feelings immediately after using the search graphic, the interaction affected perceived risk (the longer the search to find affected stick figures, the higher the risk feeling: ρ = 0.57; P = 0.009). Limitations. The authors used hypothetical decisions. . A game-like graphic that allowed consumers to search for stick figures affected by disease had no main effect on risk perception but reduced differences based on numeracy. In one condition, the game-like graphic increased concern about rare risks. Intentions for preventive action were stronger with a question order that focused first on efficacy and disease severity than with one that focused first on perceived risk.

Motion patterns in political speech and their influence on personality ratings

When people form impressions about others, they are mostly influenced by non-verbal cues. Thus, politicians and other leaders are judged by the behavior they display. To analyze the relation between non-verbal behavior and impression formation body movements of politicians giving a speech were transformed into animated stick figures. Subjects then rated the stick-figure movies on the five factor model of personality. Motion analysis revealed that observers associate extraversion, agreeableness, conscientiousness, emotional stability and openness with different motion qualities such as the amount of motion and its flow. Additionally, we found significant correlations between these personality traits and dominant activation of different body parts. The current study underlines that body motion is a powerful signal in human communication.

Visualisation of biomechanical data to assist therapeutic rehabilitation

PURPOSE: The biomechanics community have to date had limited success in communicating complex biomechanical data and analyses outside of their field. The authors have created an innovative prototype software tool to visualise objective dynamic movement data captured from older adults undertaking activities of daily living (ADLs). Evaluation of this tool has shown it to be a successful way of communicating the complexity of older adult mobility data in an accessible manner for non-biomechanical specialists and lay audiences(1,2). METHODS: A software tool was developed, which generates a 3D animated human 'stick figure', on which the biomechanical demands of ADLs are represented visually at the joints as a percentage of each individual's maximum capability using a continuous colour gradient from green at 0%, amber at 50%, through to red at 100% (Figure 1). The tool was evaluated using a qualitative methodology of interviews and focus groups, where older adults and professionals viewed a series of visualisations of dynamic movement data(3). RESULTS AND DISCUSSION: Analysis of focus group discussions facilitated by the visualizations revealed new kinds of dialogues about biomechanical issues. The method of visualising and presenting the data clearly enabled people without training in biomechanics, both professionals and lay older people, to access and interpret the biomechanical information, based on their background, knowledge of a field or their personal experience. Further, the common visual medium enabled the sharing of different insights without recourse to specialist terminology or knowledge. New kinds of dialogues occurred in focus groups between older people and professionals about their experiences, based on real understanding of where the mobility problems were occurring. New dialogues also emerged between professionals from a range of different disciplines, crucial for different aspects of the care, wellbeing or design of the built environment for older people. Neither of these would have been possible using current conventions of presenting biomechanical data. The visualisations also appear to allow a deeper understanding of the issues within professions, both in healthcare and in design. These findings have led to new research with five discrete yet complementary studies covering a range of clinical applications of this method for: i) mobility and exercise advice for the healthy older adult; ii) falls prevention; iii) rehabilitation of total knee replacement; iv) to enhance early mobilisation of acute stroke patients and v) to enhance biomechanical diagnosis and fitting of ankle foot orthoses (AFO) in late stage stroke.

Perceived health from biological motion predicts voting behaviour

Body motion signals socially relevant traits like the sex, age, and even the genetic quality of actors and may therefore facilitate various social judgements. By examining ratings and voting decisions based solely on body motion of political candidates, we considered how the candidates' motion affected people's judgements and voting behaviour. In two experiments, participants viewed stick figure motion displays made from videos of politicians in public debate. Participants rated the motion displays for a variety of social traits and then indicated their vote preference. In both experiments, perceived physical health was the single best predictor of vote choice, and no two-factor model produced significant improvement. Notably, although attractiveness and leadership correlated with voting behaviour, neither provided additional explanatory power to a single-factor model of health alone. Our results demonstrate for the first time that motion can produce systematic vote preferences.

Movement synchrony and perceived entitativity

Movement synchrony has been theoretically linked to the emergence of a social unit. To empirically investigate whether similar movement rhythms are an antecedent of perceived entitativity, movement rhythms were experimentally manipulated in four studies. Using this novel approach, stick figures waving in synchrony were found to be rated higher on entitativity than stick figures waving in different rhythms (Study 1), and this effect was extended to interactional synchrony, where different movements are performed in the same rhythm (Study 2). Objective differences in movement rhythms are linearly related to ratings of perceived entitativity, and this relationship is partially mediated by the subjectively perceived similarity of movement rhythms (Study 3). These results also held for entitativity judgments for videotaped individuals waving rhythmically (Study 4). These results support the hypothesis that movement rhythms are an important source of information which observers use to infer the extent to which individuals are a social unit.

Learning Articulated Structure and Motion

Humans demonstrate a remarkable ability to parse complicated motion sequences into their constituent structures and motions. We investigate this problem, attempting to learn the structure of one or more articulated objects, given a time series of two-dimensional feature positions. We model the observed sequence in terms of "stick figure" objects, under the assumption that the relative joint angles between sticks can change over time, but their lengths and connectivities are fixed. The problem is formulated as a single probabilistic model that includes multiple sub-components: associating the features with particular sticks, determining the proper number of sticks, and finding which sticks are physically joined. We test the algorithm on challenging datasets of 2D projections of optical human motion capture and feature trajectories from real videos.

Building back better? – negotiating normative boundaries of gender mainstreaming and post-tsunami reconstruction in Nanggroe Aceh Darussalam, Indonesia

AbstractThis article focuses on gender mainstreaming policies and advocacy on gender equality in the post-tsunami context in Nanggroe Aceh Darussalam. Through the analysis, this article illustrates how gender mainstreaming policy documents and gender advocacy of the provincial and central government, when drawing from sex/gender division and binary of genders, reproduce heteronormative boundaries. By focusing on details, I argue that the image of the heteronormative nuclear family participates in normalising other identity categories; such as urban and middle-class. I also provide examples of how simultaneous to the production of dominant norms, gender advocacy challenges heteronormativity and norms governing heterosexuality and actively question the dominant gender norms. Drawing from postcolonial feminist and recent queer critiques, I argue that advocacy that solely focuses on gender and/or sexuality reduces human bodies and their desires to simplistic stick figures. Thus, it remains blind to other forms of violence, such as global economic and political frameworks that define ‘building back better’ primarily as recovery and rehabilitation of economy, assets and labour force.

SOM型パターン生成器：自己組織化マップの逆投影に基づいた新規パターンの生成とその応用

A major feature of the self-organizing map (SOM) is a topology-preserving projection from the input layer to the competitive layer, and it has been used mainly as an analytical tool for discovering underlying rules in the given data set. Even though recent splendid progress in this area, there are few novel ideas to break such a conventional style. On the contrary, based on its distinctive nature, a new method for generating patterns through backward projection from the competitive layer to the input layer is proposed recently. Moreover, a promising technology for producing animation as a series of backward-projected patterns along with any pathways on the competitive layer is presented. Then, in order to carry out further considerations, some computer simulations with a variety of posed stick figures are tried in this paper. After training, four kinds of pathways, which correspond to different movements such as dancing, exercising and walking, are prepared. Though some of them does not contain any training samples, all of them worked well as we have intended in advance. As a result, it is found that the proposed method shows good performance and it is also confirmed its effectiveness.

Anticipating drug resistance in the MAP kinase pathway

Anticipating drug resistance in the MAP kinase pathway

The effect of leg length on perceived attractiveness of simplified stimuli.

In Western culture there are countless examples of reference to female legs as a factor in sexual attraction. It is not surprising, therefore, that both males and females perceive female figures as more attractive as leg length increases, in proportion to torso or stature, and perhaps the opposite should be true for male figures. Both evolutionary and socio cultural factors can play a role in the effect, such as the emphasis on longer legs in images of attractive women. To isolate leg length from other factors we conducted three studies using an extremely simplified type of stimulus: stick figures. Results using three different dependent variables (a forced choice, a rating, and a production task) confirm a role for leg length in attractiveness judgments, modulated also by level of estimated self attractiveness. We discuss the potential of simplified stimuli, which do not attempt to appear realistic, as a tool in the study of factors affecting attractiveness.

Gait posture estimation using wearable acceleration and gyro sensors

A method for gait analysis using wearable acceleration sensors and gyro sensors is proposed in this work. The volunteers wore sensor units that included a tri-axis acceleration sensor and three single axis gyro sensors. The angular velocity data measured by the gyro sensors were used to estimate the translational acceleration in the gait analysis. The translational acceleration was then subtracted from the acceleration sensor measurements to obtain the gravitational acceleration, giving the orientation of the lower limb segments. Segment orientation along with body measurements were used to obtain the positions of hip, knee, and ankle joints to create stick figure models of the volunteers. This method can measure the three-dimensional positions of joint centers of the hip, knee, and ankle during movement. Experiments were carried out on the normal gait of three healthy volunteers. As a result, the flexion–extension (F–E) and the adduction–abduction (A–A) joint angles of the hips and the flexion–extension (F–E) joint angles of the knees were calculated and compared with a camera motion capture system. The correlation coefficients were above 0.88 for the hip F–E, higher than 0.72 for the hip A–A, better than 0.92 for the knee F–E. A moving stick figure model of each volunteer was created to visually confirm the walking posture. Further, the knee and ankle joint trajectories in the horizontal plane showed that the left and right legs were bilaterally symmetric.

Interactive Graphics for Expressing Health Risks: Development and Qualitative Evaluation

Recent findings suggest that interactive game-like graphics might be useful in communicating probabilities. We developed a prototype for a risk communication module, focusing on eliciting users' preferences for different interactive graphics and assessing usability and user interpretations. Feedback from five focus groups was used to design the graphics. The final version displayed a matrix of square buttons; clicking on any button allowed the user to see whether the stick figure underneath was affected by the health outcome. When participants used this interaction to learn about a risk, they expressed more emotional responses, both positive and negative, than when viewing any static graphic or numerical description of a risk. Their responses included relief about small risks and concern about large risks. The groups also commented on static graphics: arranging the figures affected by disease randomly throughout a group of figures made it more difficult to judge the proportion affected but often was described as more realistic. Interactive graphics appear to have potential for expressing risk magnitude as well as the feeling of risk. This affective impact could be useful in increasing perceived threat of high risks, calming fears about low risks, or comparing risks. Quantitative studies are planned to assess the effect on perceived risks and estimated risk magnitudes.

2D shape manipulation via topology‐aware rigid grid

AbstractThis paper presents a new method which allows user to manipulate a two‐dimensional shape in an intuitive and flexible way. The shape is discretized as a regular grid. User places handles on the grid and manipulates the shape by moving the handles to the desired positions. To meet the constraints of the user's manipulation, the grid is then deformed in an as‐rigid‐as‐possible way. However, this straightforward approach tends to produce unnatural deformations when the grid resolution is not high enough to capture the topological structure of the shape. In the proposed method, the regular grid is trimmed and only the cells that are inside the fatty regions of the shape are preserved, namely “interior grid.” When user manipulates the shape, the interior grid and the shape boundary curve are deformed with minimum distortions. To make the deformations of the interior grid and the boundary curve consistent, a junction energy is introduced. In this way, the unnatural deformation effects could be effectively removed and the physically plausible results can be obtained. Meanwhile, the proposed approach provides user an intuitive and simple way to adjust the shape global and local stiffnesses. The deformation is formulated as an energy minimization problem. The energy function is non‐quadratic and could be efficiently solved using an iterative solver with the fast summation technique that exploits the interior grid and boundary curve regularities. In addition, the method could be easily extended to manipulate curves and stick figures. Experimental results demonstrate the capability and flexibility of the new method. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Arcady and After

Arcady and After Mairi MacInnes (bio) Maggy Johnston and Piet VanDongen, a married couple who had lived and worked abroad for most of their married life, decided several years before they were due to retire that they would find a moorland village in the north of England, where she had grown up, and buy a pretty house there. They would fit out the house, cultivate a garden, entertain old friends, make new ones, write books, and travel. And so it came to pass. One day Appleby-le-Moors found strangers moving into the old miller’s house on the green, and Maggy and Piet found people smiling at them on the street as if they knew who they were. “Why Appleby?” the postmaster wondered when Maggy introduced herself in his village shop. “Because it’s always been a lovely village,” Maggy said. “It was, and it still is.” “And your husband?” “The Netherlands are not far away. Overnight from Hull.” “Welcome,” said the postmaster, the former accounting manager for a firm making agricultural machinery. “May you be happy here.” “I have a lot of looking round to do,” Maggy confessed. “Not a difficult task. And it’s very moving. To find places much the same, you know.” The postmaster looked at the neat gray-haired lady in her gray trousers and black quilted jacket, her silver earrings and necklace, and took in her amusement. “It’s so beautiful!” she added. “For years I’ve lived in places where I didn’t particularly want to live—Chicago and Toronto and Los Angeles, places where we worked. Interesting, of course, but without the resonance I find here.” “And your husband?” “He can’t get over it. Where are the dark satanic mills? he asks. Where are the sooty working-class terraces and the factory chimneys and the stick figures of Mr. Lowry?” “You can get to Bradford by train quite easily,” said the postmaster humorously. “We’re in a ‘Place of Outstanding Natural Beauty,’ don’t forget.” [End Page 410] “As if that nailed it.” Yet surprise bore Piet along like a wave. Why? Maggy wondered, walking home with the newspaper. But beauty is always going to be foreign, and Maggy needed familiarity. That is why she decided to go with Piet back to the boarding school a few miles off, where she had been happy long ago, and where she might anchor her shapeless longing on the once familiar. By no coincidence both house and gardens of the school were outstanding of their kind, the eighteenth-century grand English or Scottish kind. That had provided a good reason for Maggy’s parents to send her there, so some of the distinction might rub off on her, rough little creature as she’d been. And that was the good reason too for Piet, an architect and connoisseur of houses, to accompany her. The house had been designed about 1700 by a gentleman of the neighborhood, one of those amateurs of the classical age who erected a single masterpiece before going back to private life. To reach it Maggy and Piet drove through two sets of huge wrought-iron gates and two lots of parkland, all grass and vast oaks, and then whirled over a graveled courtyard to the double staircase of the house that led up to the entrance above. “Enough to make you turn in your suit,” said Piet, who had picked up his splendid English before the colloquialisms of television. “A nice color, this stone. Nice and warm. Still the building is hideous. Guess why it’s a school.” “Come, Piet, it’s absolutely beautiful.” “In the Netherlands people have more respect for the public than to do this sort of thing. Showing off in this totally unscrupulous way.” Maggy laughed. “You’re a snob, Piet. Yet you’re right—when the house burnt down in the 1880s, the family had the cheek to build it again.” “Bad electrics, sure.” “They liked grandeur. Someone told me that the local vicar was incensed at the time. He wrote that tenants in the village lived in leaking hovels. He said that the lord of the manor had a moral duty to tend...

A sketch-based approach to human body modelling

In this paper, we present a new approach and a novel interface, Virtual Human Sketcher (VHS), which enables those who can draw, to sketch-out various human body models. Our approach supports freehand drawing input and a ''Stick Figure->Fleshing-out->Skin Mapping'' modelling pipeline. Following this pipeline, a stick figure is drawn first to illustrate a figure pose, which is automatically reconstructed into 3D through a ''Multi-layered Back-Front Ambiguity Clarifier''. It is then fleshed-out with freehand body contours. A ''Creative Model-based Method'' is developed for interpreting the body size, shape, and fat distribution of the sketched figure and transferring it into a 3D human body through graphical comparisons and generic model morphing. The generic model is encapsulated with three distinct layers: skeleton, fat tissue, and skin. It can be transformed sequentially through rigid morphing, fatness morphing, and surface matching to match the 2D figure sketch. The initial resulting 3D body model can be incrementally modified through sketching directly on the 3D model. In addition, this body surface can be mapped onto a series of posed stick figures to be interpolated as a 3D character animation. VHS has been tested by various users on Tablet PC. After minimal training, even a beginner can create plausible human bodies and animate them within minutes.

A Dance to the Music of Time: Aesthetically-Relevant Changes in Body Posture in Performing Art

In performing arts, body postures are both means for expressing an artist's intentions, and also artistic objects, appealing to the audience. The postures of classical ballet obey the body's biomechanical limits, but also follow strict rules established by tradition. This combination offers a perfect milieu for assessing scientifically how the execution of this particular artistic activity has changed over time, and evaluating what factors may induce such changes. We quantified angles between body segments in archive material showing dancers from a leading company over a 60-year period. The data showed that body positions supposedly fixed by codified choreography were in fact implemented by very different elevation angles, according to the year of ballet production. Progressive changes lead to increasingly vertical positions of the dancer's body over the period studied. Experimental data showed that these change reflected aesthetic choices of naïve modern observers. Even when reduced to stick figures and unrecognisable shapes, the more vertical postures drawn from later productions were systematically preferred to less vertical postures from earlier productions. This gradual change within a conservative art form provides scientific evidence that aesthetic change may arise from continuous interaction between artistic tradition, individual artists' creativity, and a wider environmental context. This context may include social aesthetic pressure from audiences.

Energy Cost and Pole Forces during Nordic Walking under Different Surface Conditions

The purpose of the study was to identify the effect of three different surfaces on energy consumption and the forces acting on the walking poles during ground contact in Nordic walking (NW). Thirteen female NW instructors (age = 26 +/- 4 yr, weight = 58.5 +/- 4.2 kg, height = 168.1 +/- 4.6 cm) volunteered in the study. The subjects walked a distance of 1200 m at a controlled, constant speed of 2.2 m x s(-1) on each of a concrete surface (C), an artificial athletics track (A), and a naturally grown soccer lawn (G). They used NW poles with inbuilt strain gauge force transducers to measure ground reaction forces acting along the long axes of the poles. Oxygen uptake, capillary blood lactate (La), HR, and RPE were measured before and after the tests. Impact forces, maximum forces, force rates during ground contact identified from the registered force time histories, displayed significant differences related to the surface conditions. However, force time integrals did not show surface-related differences. Relative oxygen consumption showed significant differences between NW on C and on G whereas no surface-related differences could be identified between the surface conditions for the parameters La, HR, and RPE. Our data indicate that the impulse that is generated by the poles on the subjects is identical between the varying surfaces. Because there are differences for the oxygen uptake between C and G, the main regulator for the propulsion must be the musculature of the lower extremities. The work of the upper extremities seems to be a luxury effort for Nordic walkers with a proper technique.