Asymmetric Performance During Discrimination of Sound Motion Direction in Dichotic Conditions
This study focused on the left-right asymmetry in the discrimination of moving sound stimuli in dichotic conditions. Healthy adult right-handed participants discriminated left or right direction of motion. The sound stimuli consisted of two parts: a stationary midline sound followed by moving fragments of various durations which shifted leftward or rightward from midline. Seven velocities of motion (from 80 to 480 deg/s) were produced by linear changes of interaural time differences (ITDs). Hit rates and mean reaction times were measured separately in each of the conditions. With increasing task complexity due to decreasing sound shifts in shorter time, the percentage of rightward responses became higher than that of leftward responses. However, the total amount of leftward responses contained a larger portion of hits. This asymmetry in performance showed no correlation with the consistency of hand preference.