Matthew Turner
Bruce G. Berg
Curt Southworth
Dept. of Cognitive Sci., Univ. of California, Irvine, CA 92717
This study examined observer's decision strategies in profile analysis experiments when cues based on both absolute-intensity and across-channel relative-intensity information were simultaneously available. The standard, in a 2IFC task, consisted of five equal-intensity tones, centered at 1000 Hz and ranging from 200 Hz to 5 kHz; the signal was an intensity increment added to the center tone. Two observers were initially trained in single-tone intensity discrimination tasks; another was trained in profile analysis tasks. In the first condition, unlike typical profile tasks, the overall level was not varied (e.g., roving-level procedure) thus making absolute-intensity and relative-intensity cues available. Spectral weight estimates for single tone trained observers were positive for all components of the stimulus. These results are consistent with absolute-intensity comparisons. Next, when a roving level procedure was used, spectral weight estimates changed to a pattern indicative of across-channel comparisons. Finally, when absolute intensity cues were again made available to the observers, they continued to use across-channel comparisons. The profile trained observer had constant (across-channel) weights which did not change. This suggests that observers choice of cues can be affected by training or previous listening experience. [Work supported by ONR.]