Selection of reference frames and the 'vicariance' of perceptual systems.

Abstract

Interindividual differences in field dependence-independence (FDI) which emerge in situations of vision-posture conflict when subjects are required to orient their bodies vertically were investigated. The first aim was to see whether the same interindividual differences are found in judgements of the orientation of forms in focal vision in which subjects have to deal with conflicting spatial references processed by different sensory modalities. The second aim was to test the idea that the FDI dimension is due to functional habits linked to balancing. Subjects performed Kopfermann's (1930) shape-orientation task in either a stable (experiment 1) or an unstable (experiment 2) postural condition. Results showed that the FDI dimension comes into play in the solution of the Kopfermann shape orientation task, and that there is an interactive link between FDI and postural balance, consistent with theoretical expectations. More generally, it appears that the 'choice' of a spatial reference system is the product of both individual and situational characteristics, and that the 'vicariance' (or interchangeability) of the sensory systems dealing with gravitational upright is at the basis of this interaction.