Cue-specific effects of categorization training on the relative weighting of acoustic cues to consonant voicing in English

Abstract

In English, voiced and voiceless syllable-initial stop consonants differ in both fundamental frequency at the onset of voicing (onset F0) and voice onset time (VOT). Although both correlates, alone, can cue the voicing contrast, listeners weight VOT more heavily when both are available. Such differential weighting may arise from differences in the perceptual distance between voicing categories along the VOT versus onset F0 dimensions, or it may arise from a bias to pay more attention to VOT than to onset F0. The present experiment examines listeners' use of these two cues when classifying stimuli in which perceptual distance was artificially equated along the two dimensions. Listeners were also trained to categorize stimuli based on one cue at the expense of another. Equating perceptual distance eliminated the expected bias toward VOT before training, but successfully learning to base decisions more on VOT and less on onset F0 was easier than vice versa. Perceptual distance along both dimensions increased for both groups after training, but only VOT-trained listeners showed a decrease in Garner interference. Results lend qualified support to an attentional model of phonetic learning in which learning involves strategic redeployment of selective attention across integral acoustic cues.

Figure 1

Hypothetical illustration of changes in perceptual space from equally balanced performance on pretest (1a) to increased attention to VOT∕decreased attention to F0 (1b) or decreased attention to VOT∕increased attention to F0 (1c). Axes are measured in arbitrary units of perceptual distance.

Figure 2

Proportion of correct consonant identification responses on the first and last days of training for both training groups (successful learners only, see text). Error bars indicate standard error of the mean.

Figure 3

Pretest and post-test response times on the Garner base line task, classifying stimuli as either [b] or [p] (trained dimension) or “stressed” or “unstressed” (untrained dimension) for both training groups, separated by dimension of classification. Error bars indicate standard error of the mean.

Figure 4

Garner interference (difference between RT on the Garner filtering task and RT on the Garner base line task, see text for description of tasks) showing significant interaction between test and dimension of classification. Error bars indicate standard error of the mean.

Figure 5

Differential effects of training on Garner interference (difference between RT on the Garner filtering task and RT on the Garner base line task) for VOT- and F0-trained groups, separated by dimension of classification. Error bars indicate standard error of the mean.