Effect of orientation in haptic reproduction of line length.

We investigated the accuracy of haptic reproduction of line length and whether accuracy is influenced by line orientation. 13 blindfolded subjects felt along different line lengths at various orientations in the horizontal plane, then reproduced the line lengths in the same orientation as that felt. Efforts were made to equate learning and reproductive scanning movements. Reproductions of line lengths were a nonveridical power function of their true lengths, but the power function exponents did not differ across spatial orientations. It was concluded that people can encode line lengths across spatial orientations by a common power function if care is taken to equate proprioceptive information across learning and reproduction.