Properties of feature detectors for speech: Evidence from the effects of selective adaptation on dichotic listening

Abstract

Two selective adaptation experiments were conducted in order to investigate certain properties of feature detector systems sensitive to the information underlying the voicing distinction (Experiment I) and the place of articulation distinction (Experiment II). The experimental paradigm combined binaural adaptation with a dichotic testing procedure. The stimuli were nonboundary, good exemplars of the respective phonetic categories. In both experiments, there was a systematic shift in performance following adaptation on those trials on which the stimulus in one ear had the adapted feature value and the stimulus in the other ear had the unadapted feature value. On these trials, the adapted feature value was relatively less effective in competing for processing with the unadapted value in the opposing ear (compared to preadaptation performance). Since these results were obtained using nonboundary stimuli, it was argued that (1) adaptation affects the relevant detector along its range of operation or sensitivity, and nof simply at the phonetic boundary, and that (2) information regarding the relative output level of the detector, as well as which detector was more strongly excited, must be available at the site of interaction of the two stimuli. © 1975 Psychonomic Society, Inc.