Perception of motion trajectory of object from the moving cast shadow in infants

A moving cast shadow of the object affects the perception of the object's trajectory in adults [Kersten, D., Mamassian, P., & Knill, D. C. (1997). Moving cast shadow induce apparent motion in depth. Perception, 26, 171-192]. In the present study, we investigated by using a habituation-dishabituation procedure whether infants at 4- to 7-months old discriminate the motion trajectory of a ball from the moving shadow it casts. In Experiment 1, 4- to 5-month-old and 6- to 7-month-old were tested for ability to discriminate between a "depth" display containing a ball and a cast shadow with a diagonal trajectory and an "up" display containing a ball with a diagonal trajectory and a cast shadow with a horizontal trajectory. Six- and 7-month-old, but not 4- and 5-month-old, infants looked significantly longer at the "up" display than at the "depth" display. In Experiment 2, we tested whether 4- to 5-month-old and 6- to 7-month-old infants would perceive "up" motion as categorically different from "depth" depending on the object's 3-D trajectory. We used displays containing a ball and a cast shadow with the same trajectories as those in Experiment 1 except that the cast shadows appeared above the ball. These displays did not produce 3-D impressions in adults. Neither age group of infants exhibited significant differences between "up" and "depth" displays. When the results from the two experiments are considered, 6- and 7-month-old infants discriminated the motion trajectory of the ball from the moving cast shadows. This developmental emergence of depth perception from a moving cast shadow at 6 months of age is consistent with that of other pictorial depth cues.

[1]  A. Yonas,et al.  Infants’ sensitivity to the depth cue of shading , 1985, Perception & psychophysics.

[2]  Albert Yonas,et al.  Infants' distance perception from linear perspective and texture gradients , 1986 .

[3]  J. Náñez.  Perception of impending collision in 3-to 6-week-old human infants , 1988 .

[4]  E. Spelke,et al.  Perception of partly occluded objects in infancy , 1983, Cognitive Psychology.

[5]  Albert Yonas,et al.  Effects of luminance and texture motion on infant defensive reactions to optical collision , 1994 .

[6]  R. Bhatt,et al.  Perception of three-dimensional cues in early infancy. , 1998, Journal of experimental child psychology.

[7]  Albert Yonas,et al.  Infants' Sensitivity to Relative Size Information for Distance. , 1985 .

[8]  D. Knill,et al.  The perception of cast shadows , 1998, Trends in Cognitive Sciences.

[9]  Paul C Quinn,et al.  Spatial representation by young infants: Categorization of spatial relations or sensitivity to a crossing primitive? , 2004, Memory & cognition.

[10]  J. Atkinson,et al.  Some recent findings on the development of human binocularity: A review , 1983, Behavioural Brain Research.

[11]  Vision Research , 1961, Nature.

[12]  C. Hofsten,et al.  Young infants' sensitivity to motion parallax , 1992 .

[13]  D Kersten,et al.  Moving Cast Shadows Induce Apparent Motion in Depth , 1997, Perception.

[14]  P J Kellman,et al.  Object and observer motion in the perception of objects by infants. , 1987, Journal of experimental psychology. Human perception and performance.

[15]  Thomas E. Dawson,et al.  The Perception and Recognition of Natural Object Shape from Deforming and Static Shadows , 2000, Perception.

[16]  A Yonas,et al.  Development of Sensitivity to Information Provided by Cast Shadows in Pictures , 1978, Perception.

[17]  Scott P. Johnson,et al.  Young Infants' Perception of Illusory Contours in Dynamic Displays , 1998, Perception.

[18]  J. Koenderink,et al.  Perception of local shape from shading , 1993, Perception & psychophysics.

[19]  R. Held,et al.  Stereoacuity of human infants. , 1980, Proceedings of the National Academy of Sciences of the United States of America.

[20]  A Yonas,et al.  Infants' sensitivity to familiar size as information for distance. , 1982, Child development.

[21]  C. Granrud.  Binocular vision and spatial perception in 4- and 5-month-old infants. , 1986, Journal of experimental psychology. Human perception and performance.

[22]  Scott P. Johnson,et al.  Perception of object unity in 2-month-old infants. , 1995 .

[23]  K Berbaum,et al.  Extending the Perception of Shape from Known to Unknown Shading , 1984, Perception.

[24]  B. Bertenthal,et al.  Infants' perception of object unity in translating and rotating displays. , 1998, Developmental psychology.