Lateralization and the MLD: The Vector Summation Model

At the Houston meeting, the first author reported the results of an experiment requiring discrimination between various combinations of interaural time and intensity cues. Performance could be described quite well by a simple vector summation of performances with each cue alone. The angle, η, between the vectors provided an estimate of the correlation of the two cue dimensions in the psychological discrimination space. Similar data reported recently by Jeffress and McFadden [J. Acoust. Soc. Amer. 52, 1197–1206 (1972); 50, 1484–1493 (1971)] provided the opportunity to extend the vector summation model into an MLD paradigm. As in our earlier work, one angle, η, along with an efficiency ratio, reflecting the relative sensitivity of each observer to interaural time and intensity differences, predicted performance well for all values of alpha; that is, performance for cue conditions in which time and intensity differences are consonant or dissonant can be described by the same vector summation process. An analysis of changes in efficiency ratio and η across observers and frequency, along with a comparison of these parameters in the detection and lateralization tasks will be presented.