Quantitative analysis of onset dominance in lateralization

Abstract

A statistical method for measuring the weight which an observer gives to each component of a multicomponent signal [COSS Analysis; Berg, J. Acoust. Soc. Am. 86, 1743–1746 (1989)] was applied to precedence. Signals consisted of trains of dichotic clicks whose time envelopes were Gaussian and centered at the cosine phase of a 6-kHz carrier. The interaural delay of each click was perturbed by adding or subtracting a small Gaussian random variable. In a single-interval task, subjects were required to determine whether the lateralized image was to the right or left of the head. Using COSS analysis, weights were determined for each click of the multiclick stimulus. For short interclick intervals (ICI=1.8 ms) as the number of clicks increased (n=2 to 16), the relative weight given to the onset click diminished. The weights estimated for all clicks following the first were nearly the same. Only the relative weight of the first click varied as stimulus parameters were altered. Frequency-channel effects and the idea of restarting in binaural adaptation were also examined. [Work supported by NIH and AFOSR.]