Evaluation of response methods for the localization of nearby objects.

Four response methods for indicating the perceived locations of nearby objects were evaluated: the direct-location (DL) method, where a response pointer is moved directly to the perceived location of the target; the large-head (LH) and small-head (SH) methods, where the pointer is moved to the target location relative to a full-scale or half-scale manikin head; and the verbal report (VR) method, where the spherical coordinates of the target location are indicated verbally. Measurements with a visual target indicated that the DL method was relatively unbiased and considerably more accurate than the other methods, which were all roughly equivalent. Correcting for bias improved accuracy in the LH, SH, and VR responses, but not to the level of the uncorrected DL responses. Replacing the visual target with an acoustic stimulus approximately doubled the errors with the DL response but indicated similar performance in the front and rear hemispheres. The results suggest that DL is the most appropriate response method for close-range localization experiments.