Research indicates that infants have expectations regarding the configuration of human faces from birth (Johnson, Dziurawiec, Ellis, & Morton, 1991), and have knowledge of the biomechanical properties of human movement from 5 months of age (Bertenthal, Proffitt, Kramer, & Spetner, 1987). However, little research has investigated infants' knowledge of the overall human body shape. This thesis investigated knowledge of the human body shape by presenting infants with typical and scrambled human bodies (e.g. arms extending from the head) and measuring responses (visual attention, object examination and sequential touching). A variety of body stimuli were employed, including photographs, dolls, mannequins and real humans.
Results revealed that infants demonstrated sensitivity to violations of the human body shape as early as 9 months of age when real humans or highly realistic representations of humans (mannequins) were used as stimuli. Infants demonstrated sensitivity to violations of other representations of human beings (e.g. dolls) at around 15 months of age. At 30 months, children applied self-driven touching behaviours to distinguish typical and scrambled dolls in a sequential touching task, and also made this differentiation using language. Thus, infants have a rudimentary understanding of the spatial layout of the parts of the human body shape, relative to the whole form, at 9 months of age. By 15 to 18 months of age, this representation is adequate to be utilized when infants are presented with various human body stimuli. At 30 months, children demonstrate robust human body knowledge across a variety of task methodologies.
One task parameter that had a major influence on the results, in terms of age of responding, was the type of body stimulus presented to infants. The presentation of a real human or a mannequin elicited responding up to 6 months earlier than other representations (e.g. dolls, photographs). Thus it appears that more realistic representations are more likely to trigger knowledge about the human body. Furthermore, photographs elicited earlier responding than dolls. This suggests that objects which are less compelling in their own right are more likely to trigger knowledge of real humans than highly compelling objects, which may distract infants from recognising the referent being portrayed. Other task parameters found to influence results included the task methodology (earliest responding occurred in the visual habituation procedure, fol lowed by the object examination procedure, then the sequential touching task) and the response required (infants demonstrated knowledge earliest if the response required was an increase in visual attention, followed by an increase in examination, and then sequential touching or verbal labelling of objects). It was concluded that the type of body stimulus and the task methodology interacted to produce results, providing important guidelines for further research. Thus overall, these studies document the emergence of knowledge about the human body shape in infancy, and provide insight into the influence of task parameters on infants' responding.