biological motion perception lavanya sharan march 28th, 2011

Biological Motion Perception

Lavanya SharanMarch 28th, 2011

Studying human movements

Image sources: Wikimedia Commons, science-television.comSlide content: Blake & Shiffrar (2007)

Etienne-Jules Marey (1884) developed ‘chronophotography’

Point Light Walker is born

Image source: Johansson (1973)Slide content: Blake & Shiffrar (2007)

Markers attached to head and joints.Videos of walking, running etc.

Can use animation and motion captures techniques for the same purpose.

Point light (PL) animations are now the mainstay of biological motion research.

Examples of PL motions

Video source: Randolf Blake LabSlide content: Blake & Shiffrar (2007)

Phase-scrambled motion

QuickTime™ and aSorenson Video decompressorare needed to see this picture.


Normal motion

Alternative to PL animations

Slide content: Blake & Shiffrar (2007)

Very few studies that use ‘embodied’ forms.

Hodgins et al. (1998) Knoblich & Flach (2001) McDonnell et al. (2009)

What have we learn from PLWs?



Human motion perception is quite robust.



Human motion perception is quite robust.

Brief exposures (<100 ms) Johannson 1973Blurry dots, randomized contrast polarity over timeMather et al., 1992, Ahlstrom et al. 1997Stereoscopic depths are scrambledAhlstrom et al. 1997, Bulthoff et al. 1998, Lu et al. 2006Dynamic noise dotsBertenthal & Pinto 1994, Cutting et al. 1998, Ikeda et al. 2005Markers not on jointsBertenthal & Pinto 1994



How much can we tell about a figure?Identity of figure

Cutting & Kozlowski 1977, Fani et al. 2005, Troje et al. 2005Sex of figureKozlowski & Cutting 1977, 1978, Mather & Murdoch 1994, Sumi 2000, Troje 2002, Pollick et al. 2005Activities of two or more individualsMass et al. 1971Emotional contentClarke et al. 2005, Dittrich et al. 1996, Walk & Homan 1984Facial expressionsBassili 1978, Hill et al. 2003 Interactions with objectsBingham 1993, Stoffregen & Flynn 1994



Inversion effects for body motions (Sumi 1984)




Sensitive to certain factors.Number of markers and exposure durationNeri et al. 1998, Poom & Olsson 2002, Thornton et al. 1998Impaired recognition in peripheryIkeda et al. 2005Dim lightingGrossman & Blake 1999Phase scramblingGrossman & Blake 1999, Hiris et al. 2005Temporal durationBeintema et al. 2003Relative position of markers (form)Beintema & Lappe 2002, Beintema et al. 2006, Hiris et al. 2005



Not limited to humans.




Biological recognition develops early.

4 and 8 month olds respond to human motion vs. scrambled dots.Bertenthal 1993, Fox & McDaniel 1982, Hirai & Hiraki 2005, Reid et al. 2006Reach adult level performance by age 5Pavlova et al. 2001Older adults can perceive human motion inspite of age-related deficits in visual processingNorman et al. 2004

Top-down vs. bottom-up?

Image source: cs.bham.ac.ukSlide content: Blake & Shiffrar (2007)

Low-level models of motion processing

Longer ISIs impair performance

Inversion effects

Good performance at temporal display rates higher than needed for low-level processing

Requires focused visual attention

Binocular rivalryPerceived background flow

Motoric contributions to human motion perception


Action recognition and action planning share representationsPrinz 1997, Hommel et al. 2001Carrying out the same action as the PL figure improves performanceReed & Farah 1995, Jacobs & Shiffrar 2005, Hamilton et al. 2004Better at recognizing one’s own actionsKnoblich & Flach 2001, Loula et al. 2005, Jacobs et al. 2004Individual with motor deficit perform differently on motion perception tasksBosbach et al. 2005, Funk et al. 2005, Shiffrar 2006, Pavlova et al. 2003Chameleon effectChartrand & Bargh 1999

Social cues & human motion perception


Can tell a lot about identity, sex, sexual orientation, dancing ability etc.Loula et al. 2005, Barclay et al. 1978, Brownlow et al. 1997, Montepare & Zebrowitz-McArthur 1988, Gunns et al. 2002, Runeson & Frykholm 1983Can identify emotion from PL figuresAtkinson et al. 2004, Pollick et al. 2001Angry walker easier to detect than other emotionsChouchourelou et al. 2006Chameleon effect or social mimicry important for social interactionsChartrand & Bargh 1999

Neural basis of human motion perception

Image source & slide content: Blake & Shiffrar (2007)

Neurons in macaque STS Perrett et al. 1982, 1985, Oram & Perrett 1996, Shiffrar 1994

Mirror neuronsRizzolatti et al. 2001, Rizzolatti & Craighero 2004

Many case studies of individuals with deficits including autismSchenk & Zihl 1997, Vaina et al. 1990, Cowey & Vaina 2000, Battelli et al. 2003, Jokisch et al. 2005, Blake et al. 2003, Kim et al. 2005, Virji-

Babul et al. 2003, Pavolova et al. 2006 TMS studies in STSGrossman et al. 2005

Unlike MT, STSp selective for biological motionGrossman et al. 2000, Grossman & Blake 2001, Grossman et al. 2004

Superior temporal sulcus (STSp)

Image source & slide content: Blake & Shiffrar (2007)

More activation in right hemisphere Beauchamp et al. 2003, Grossman et al. 2000, Peusken et al. 2005, Santi et al. 2003

Crude retinotopyGrossman et al. 2000

Whole body motion, motion of body partsPelphrey et al. 2003, Calvert et al. 1997, Grezes

et al. 1998, Puce et al. 1998 Statics figures do not produce activationPelphrey et al. 2003, Peuskens et al. 2005

Sounds of footstepsBidet-Caulet et al. 2005

Intentionality of actions and social judgmentsSaxe et al. 2004, Frith & Frith 1999, Morris et al. 2005, Winston et al. 2002, Allison et al. 2000, Iacoboni et al. 2004

Open questions


Connection between faces & bodies?Interactions with motor and social learning?What about more real-world stimuli?

McDonnell et al. (2009)

biological motion perception lavanya sharan march 28th, 2011

Documents