2 Perceptual Effects of Inconsistency in Human Animations

The individual shape of the human body, including the geometry of its articulated structure and the distribution of weight over that structure, influences the kinematics of a person’s movements. How sensitive is the visual system to inconsistencies between shape and motion introduced by retargeting motion from one person onto the shape of another? We used optical motion capture to record five pairs of male performers with large differences in body weight, while they pushed, lifted, and threw objects. From these data, we estimated both the kinematics of the actions as well as the performer’s individual body shape. To obtain consistent and inconsistent stimuli, we created animated avatars by combining the shape and motion estimates from either a single performer or from different performers. Using these stimuli we conducted three experiments in an immersive virtual reality environment. First, a group of participants detected which of two stimuli was inconsistent. Performance was very low, and results were only marginally significant. Next, a second group of participants rated perceived attractiveness, eeriness, and humanness of consistent and inconsistent stimuli, but these judgements of animation characteristics were not affected by consistency of the stimuli. Finally, a third group of participants rated properties of the objects rather than of the performers. Here, we found strong influences of shape-motion inconsistency on perceived weight and thrown distance of objects. This suggests that the visual system relies on its knowledge of shape and motion and that these components are assimilated into an altered perception of the action outcome. We propose that the visual system attempts to resist inconsistent interpretations of human animations. Actions involving object manipulations present an opportunity for the visual system to reinterpret the introduced inconsistencies as a change in the dynamics of an object rather than as an unexpected combination of body shape and body motion.

[1]  Nikolaus F. Troje,et al.  What is biological motion?: Definition, stimuli and paradigms , 2012 .

[2]  François Michaud,et al.  Emotion Generation Based on a Mismatch Theory of Emotions for Situated Agents , 2009 .

[3]  Bernhard Hommel,et al.  Taking the brain serious: introduction to the special issue on integration in and across perception and action , 2007, Psychological research.

[4]  R. Passingham,et al.  Brain Mechanisms for Inferring Deceit in the Actions of Others , 2004, The Journal of Neuroscience.

[5]  Michael J. Black,et al.  MoSh: motion and shape capture from sparse markers , 2014, ACM Trans. Graph..

[6]  Geoffrey P. Bingham.  Kinematic Form and Scaling: Further Investigations on the Visual Perception of Lifted Weight , 1987 .

[7]  Lawrie S. McKay,et al.  Empirical evaluation of the uncanny valley hypothesis fails to confirm the predicted effect of motion , 2014, Cognition.

[8]  Mark H Johnson,et al.  Biological Motion: A Perceptual Life Detector? , 2006, Current Biology.

[9]  Chantal Martineau,et al.  Canadian guidelines for body weight classification in adults: application in clinical practice to screen for overweight and obesity and to assess disease risk , 2005, Canadian Medical Association Journal.

[10]  L G Carlton,et al.  Perception of Kinematic Characteristics in the Motion of Lifted Weight. , 1997, Journal of motor behavior.

[11]  H. Brenton,et al.  The Uncanny Valley : does it exist ? , 2005 .

[12]  Hfd Chang,et al.  Shape-Independent Processing of Biological Motion , 2013 .

[13]  S. Runeson.  On the possibility of "smart" perceptual mechanisms. , 1977, Scandinavian journal of psychology.

[14]  Karl F. MacDorman,et al.  Revisiting the uncanny valley theory: Developing and validating an alternative to the Godspeed indices , 2010, Comput. Hum. Behav..

[15]  Daniel Jokisch,et al.  Biological motion as a cue for the perception of size. , 2003, Journal of vision.

[16]  H. Ishiguro,et al.  The uncanny advantage of using androids in cognitive and social science research , 2006 .

[17]  Alberto Menache.  Understanding Motion Capture for Computer Animation, Second Edition , 2010 .

[18]  Geoffrey P. Bingham,et al.  Seeing Where the Stone Is Thrown by Observing a Point-Light Thrower: Perceiving the Effect of Action Is Enabled by Information, Not Motor Experience , 2014 .

[19]  G. Mather,et al.  Gender discrimination in biological motion displays based on dynamic cues , 1994, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[20]  Kerri L. Johnson,et al.  Compatibility of basic social perceptions determines perceived attractiveness , 2007, Proceedings of the National Academy of Sciences.

[21]  Angela Tinwell.  The Uncanny Valley in Games and Animation , 2014 .

[22]  Geoffrey P. Bingham,et al.  Scaling Judgments of Lifted Weight: Lifter Size and the Role of the Standard , 1993 .

[23]  J. Gibson.  The Ecological Approach to Visual Perception , 1979 .

[24]  Jessica K. Hodgins,et al.  The saliency of anomalies in animated human characters , 2010, TAP.

[25]  S. Runeson,et al.  Kinematic specification of dynamics as an informational basis for person and action perception: Expe , 1983 .

[26]  Alberto Menache.  Motion Capture Primer , 2011 .

[27]  S. Runeson,et al.  Visual perception of lifted weight. , 1981, Journal of experimental psychology. Human perception and performance.

[28]  H. Ishiguro,et al.  The thing that should not be: predictive coding and the uncanny valley in perceiving human and humanoid robot actions , 2011, Social cognitive and affective neuroscience.

[29]  J. Trafton,et al.  The Perception of Humanness from the Movements of Synthetic Agents , 2011, Perception.

[30]  Weidong Geng,et al.  Reuse of Motion Capture Data in Animation: A Review , 2003, ICCSA.

[31]  N. Troje.  Decomposing biological motion: a framework for analysis and synthesis of human gait patterns. , 2002, Journal of vision.

[32]  G. Johansson.  Visual perception of biological motion and a model for its analysis , 1973 .

[33]  Michael Gleicher,et al.  Retargetting motion to new characters , 1998, SIGGRAPH.

[34]  James J. Hoffmann,et al.  An Investigation of the Sled Push Exercise: Quantification of Work, Kinematics, and Related Physical Characteristics , 2014 .

[35]  Ludovic Hoyet,et al.  Evaluating the distinctiveness and attractiveness of human motions on realistic virtual bodies , 2013, ACM Trans. Graph..

[36]  Nikolaus F. Troje,et al.  Retrieving Information from Human Movement Patterns , 2008 .

[37]  Nikolaus F Troje,et al.  Gaze patterns during perception of direction and gender from biological motion. , 2010, Journal of vision.

[38]  Jaeho Shim,et al.  Estimation of Lifted Weight and Produced Effort through Perception of Point-Light Display , 2004, Perception.

[39]  Maggie Shiffrar,et al.  People Watching: Social, Perceptual, and Neurophysiological Studies of Body Perception , 2012 .

[40]  D. W. Joyce,et al.  Kinematic cues in perceptual weight judgement and their origins in box lifting , 2007, Psychological research.

[41]  Claudia E. Cohen,et al.  Person categories and social perception: Testing some boundaries of the processing effect of prior knowledge. , 1981 .

[42]  Alberto Menache,et al.  Understanding Motion Capture for Computer Animation and Video Games , 1999 .

[43]  Ludovic Hoyet,et al.  Eye-tracktive: Measuring Attention to Body Parts when Judging Human Motions , 2015, Eurographics.

[44]  N. Troje,et al.  Person identification from biological motion: Effects of structural and kinematic cues , 2005, Perception & psychophysics.

[45]  Michael J. Black,et al.  Coregistration: Simultaneous Alignment and Modeling of Articulated 3D Shape , 2012, ECCV.

[46]  Stefan M. Grünvogel,et al.  How Realistic is Realism? Considerations on the Aesthetics of Computer Games , 2004, ICEC.

[47]  Nikolaus F. Troje,et al.  Perceived naturalness of human motion depends on internal consistency , 2012 .

[48]  J. Kätsyri,et al.  A review of empirical evidence on different uncanny valley hypotheses: support for perceptual mismatch as one road to the valley of eeriness , 2015, Front. Psychol..

[49]  Jessica K. Hodgins,et al.  Virtual shapers & movers: form and motion affect sex perception , 2007, APGV.

[50]  Carol O'Sullivan,et al.  Clone attack! Perception of crowd variety , 2008, ACM Trans. Graph..

[51]  Angela Tinwell,et al.  Perception of psychopathy and the Uncanny Valley in virtual characters , 2013, Comput. Hum. Behav..

[52]  Nikolaus F. Troje,et al.  Internal consistency predicts attractiveness in biological motion walkers , 2016 .

[53]  Sebastian Thrun,et al.  SCAPE: shape completion and animation of people , 2005, SIGGRAPH '05.

[54]  Cord Westhoff,et al.  Kinematic cues for person identification from biological motion , 2007, Perception & psychophysics.

[55]  Takashi Minato,et al.  Generating natural motion in an android by mapping human motion , 2005, 2005 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[56]  Wen Gao,et al.  Point-Light Display , 2009, Encyclopedia of Biometrics.

[57]  Ernst-Joachim Hossner,et al.  Discriminating throwing distances from point-light displays with masked ball flight , 2010 .