The effect of cane length on the haptic perception of height

The purpose of this investigation was to determine whether the ability to haptically perceive object height is a function of the length of cane being wielded by blindfolded individuals.

Fifteen sighted females between the ages of 18 and 25 years volunteered to participate in the study. Five different heights of wooden blocks were haptically explored with four different cane lengths (0.92, 1.22, 1.37 and 1.67 m), cane length order being randomized across 2 days of testing. Subjects were asked to report whether the explored block's height was taller, shorter, or equal to that of a previously presented standard block. The percentages of correct judgments for each cane and block height combination were subjected to statistical analysis.

The analysis revealed significant main effects for cane length, F (3, 42) = 9.47, p < 0.0001, and block height, F (4, 56) = 17.69, p < 0.0001. The interaction of cane length and block height was not significant, F < 1. The accuracy of haptic perception improved with decreased cane length and increased difference in height from the standard block.

Contrary to previous research on haptic perception in which probe length was found not to affect judgment accuracy, the present study found a marked influence of cane length on perceptual accuracy. This finding indicates that length is an important property that should be taken into account when prescribing canes for the visually impaired.