Main axis of elongation dynamics and the planar bias in active object inspection: a developmental approach

Poster apresentado em "Leuven Christmas Applied Vision Association (AVA) Conference", em Leuven, Bélgica, 2014.
As we turn our bodies, as we hold and move objects close to us and act on them, we generate dynamic views. Recent studies have examined the viewpoints that infants select during free play and found large developmental changes in dwell time distribution, namely an increasing preference for orienting objects on or around planar views – i.e. main axis is parallel (foreshortened) or perpendicular to the line of sight, and flat surfaces are perpendicular. This bias is characteristic of mature viewing and was found to promote more efficient learning. The functional role of this bias is poorly understood.
We investigated two properties that seem relevant: (1) main axis expansion/foreshortening, and (2) instability – related to dynamic viewing, where rotations around planar views typically yield larger visual changes.
In two experiments (E1: N=21, 18-24 months; E2: N = 54, 12-36 months), children inspected objects in a free play task and we measured 3D orientation; the main measures were the angle between the main axis of elongation and the line of sight, and its angular velocity and acceleration.
There were two key results: (1) main axis is typically maintained in view (infrequent foreshortening) – this suggests that elongation is a distinctive property of preferred views; (2) planar views correspond to more stable periods of the object manipulation – this suggests that sampling planar views corresponds to moments of focused attention to a particular view and perhaps learning of a static view is occurring, leaving open the question of how view transitions are integrated over time.
Fundação para a Ciência e a Tecnologia (FCT)