Abstract:
Temporal order thresholds (TOT) were measured for dichotically presented stimuli. Earlier research, using diotic or monaural presentation, required subjects to respond to the perceived spectral properties of the earlier onset stimulus. Dichotic presentation provides an opportunity for the subject to respond to ear with earlier onset, pitch with earlier onset, or both. These alternatives allowed two issues to be evaluated: (1) peripheral (changes in neural patterns) versus central coding and (2) the role of pitch processing in response specification. Contrary to arguments that TOT is the result of low level interactions or changes in peripheral coding, all values for responding based on pitch or ear were within the range of previous findings. Thresholds were largest for responding based solely on pitch presumably because temporally greater information is required to specify pitch than ear. In addition, thresholds were smallest when subjects could use a combination of ear and pitch, possibly reflecting a simpler or less uncertain task.