Abstract
The Rod and Frame Test has been used to assess the degree to which subjects rely on the visual frame of reference to perceive vertical (visual field dependence- independence perceptual style). Early investigations found children exhibited a wide range of alignment errors, which reduced as they matured. These studies used a mechanical Rod and Frame system, and presented only mean values of grouped data. The current study also considered changes in individual performance. Changes in rod alignment accuracy in 419 school children were measured using a computer-based Rod and Frame test. Each child was tested at school Grade 2 and retested in Grades 4 and 6. The results confirmed that children displayed a wide range of alignment errors, which decreased with age but did not reach the expected adult values. Although most children showed a decrease in frame dependency over the 4 years of the study, almost 20% had increased alignment errors suggesting that they were becoming more frame-dependent. Plots of individual variation (SD) against mean error allowed the sample to be divided into 4 groups; the majority with small errors and SDs; a group with small SDs, but alignments clustering around the frame angle of 18°; a group showing large errors in the opposite direction to the frame tilt; and a small number with large SDs whose alignment appeared to be random. The errors in the last 3 groups could largely be explained by alignment of the rod to different aspects of the frame. At corresponding ages females exhibited larger alignment errors than males although this did not reach statistical significance. This study confirms that children rely more heavily on the visual frame of reference for processing spatial orientation cues. Most become less frame-dependent as they mature, but there are considerable individual differences.
Highlights
Postural stability, orientation and the organisation of human movement require a complex synthesis of sensory signals from internal gravity, movement, muscle and joint receptors, and external cues, principally visual, to maintain balance
Males consistently had smaller absolute alignment errors than females, and at each age had a smaller percentage of errors greater than 5u than the females (Fig 3)
After exclusion of individuals with inconsistent alignments 85 children in the current study showed at least one negative frame effect with alignment errors exceeding 3u in the opposite direction to the frame tilt
Summary
Postural stability (balance), orientation and the organisation of human movement require a complex synthesis of sensory signals from internal gravity, movement, muscle and joint receptors, and external cues, principally visual, to maintain balance. At the perceptual level the rod and frame test provides a measure of the influence of the visual FoR upon a subject’s ability to determine vertical or upright It allows the effect of the visual FoR on postural orientation (i.e., the extent to which subjects align their body axis on axes of the visual FoR) to be measured, which in turn influences the perceived orientation of the verticality of the rod. This test was developed in the 1950’s by Witkin [1] as one of a battery of tests designed to classify cognitive styles. The ability of subjects to align a rod to vertical in the presence of a tilted surrounding frame, and their ability to identify hidden figures in a distracting background in the Embedded Figures Test was used to classify subjects as Field Dependent - strongly influenced by the visual environment, or Field Independent whose perception of vertical was less affected by the visual Frame of Reference [2]
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