The perception of affordances for the actions of other people (actors) was examined. Observers judged the maximum and preferred sitting heights of tall and short actors. Judgments were scaled in centimeters, as a proportion of the observer's leg length, and as a proportion of each actor's leg length. In Experiment 1 observers viewed live actors standing next to a chair. When judgments were scaled by actor leg length, they reflected the actual ordinal relation between the capabilities of the actors. The perception of affordances from kinematic displays was then evaluated. Observers differentiated tall and short actors, but only when the displays contained direct information about relations between the actors and the chair. It is concluded that observers can perceive affordances for the actions of actors and that kinematic displays can be enough to support such percepts if they preserve actor-environment relations that define affordances.

This study was undertaken to determine whether young children, after only a few weeks standing experience, could respond adaptively to the dynamical constraints imposed by different support surfaces. The spontaneous postural motions of young children (13-14 months old) were observed as they stood on surfaces that differed in length, friction, and rigidity. There were no externally imposed perturbations to stance. Children's postural control was remarkably adaptive: There were few falls on any of the surfaces. Moreover, the children showed surface-specific utilization of manual postural control (holding onto wooden poles), suggesting that manual control is an adaptive strategy for postural control. Finally, kinematic analysis suggested that, in some instances, children were able to employ independent control of the hips, contrary to previous models which had suggested that hip motions could not be controlled before the age of 3 years. Small, slow hip movements useful in controlling spontaneous sway (unperturbed stance) may serve as a basis for the development of larger, faster hip movements that are associated with imposed perturbations.

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We studied perception of affordances for the actions of other persons (actors) from kinematic displays. Observers judged the maximum and preferred sitting heights of tall and short actors.Judgments were scaled in centimeters, as a proportion of the observer's leg length, and as a proportion of each actor's leg length. Only when judgments were scaled by actor leg length did they reflect the actual ordinal relation benveen the capabilities of the actors. In addition, observers differentiated tall and short actors only when the displays contained direct information about relations between the actors and the chair. We concluded that observers can perceive affordances for the actions of actors, and that kinematic displays can be sufJicient to support such percepts, if they preserve actor-environment relations that define affordances. We briefly discuss implications of these findings for display design.

No abstract