司会者:内山伊知郎 ( 同志社大学) Between seven and nine months of age, human infants undergo a psychological revolution. There are so many changes in emotion, social interaction, attachment, memory, spatial understanding, joint visual attention, and brain function that leading investigators are inclined to attribute these changes to maturation. Experience seems too limited to account for the revolution. In this presentation, many different studies will point to the role of experiences created by the onset of

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... crawling in this age period as the catalyst for many, if not most, of the psychological changes. For instance, if pre-locomotor infants are provided with "artificial" locomotor experience (e.g., through the use of "walker' devices, or infant-controlled powered-mobility-apparatus), their psychological functions improve. Similarly, infants are delayed in their crawling experience (because of orthopedic, neurological, or cultural reason), such infants are similarly delayed psychologically for the period of their delay in locomotion, then improve their performance upon the delayed acquisition of locomotion. Locomotor experience affects each psychological outcome differently than it does another. That is because locomotor experience has many different manifestations. One manifestation might affect an emotional outcome, but not memory. In turn, a different locomotor experience may impact memory, but not emotion. Thus, research on the psychological consequences of locomotion gives us a handle on how psychological development takes place. In our view, such development involves the intercoordination of skills, and each outcome involves different skills being intercoordinated.