An inborn predisposition to attend to biological motion has long been theorized, but had so far been demonstrated only in one animal species (the domestic chicken). In particular, no preference for biological motion was reported for human infants of less than 3 months of age. We tested 2-day-old babies' discrimination after familiarization and their spontaneous preferences for biological vs. nonbiological point-light animations. Newborns were shown to be able to discriminate between two different patterns of motion (Exp. 1) and, when first exposed to them, selectively preferred to look at the biological motion display (Exp. 2). This preference was also orientation-dependent: newborns looked longer at upright displays than upside-down displays (Exp. 3). These data support the hypothesis that detection of biological motion is an intrinsic capacity of the visual system, which is presumably part of an evolutionarily ancient and nonspecies-specific system predisposing animals to preferentially attend to other animals.
Figure: Three sample frames taken from the animation sequences used in the study: the biological motion stimulus (i.e., the walking hen) (Top), the nonbiological motion stimulus (random motion) (Middle), and the inverted biological motion display (upside-down walking hen) (Bottom). Squares indicate the point-lights.
Wednesday, January 30, 2008
Newborn humans: predisposition for biological motion
This work demonstrates that when we are born, we have an innate bias towards attending to motions characteristic of other living things. Newborn chickens do this also. The abstract, a figure, and a video from Simion et al. :