Dynamic re-weighting of acoustic and contextual cues in spoken word recognition

Abstract

Listeners integrate acoustic and contextual cues during word recognition. However, experiments investigating this integration disrupt natural cue correlations. It was investigated whether changes in correlational structure affect listeners' relative cue weightings. Two groups of participants engaged in a word recognition task. In one group, acoustic (voice onset time) and contextual (lexical bias) cues followed natural correlations; in the other, cues were uncorrelated. When cues were correlated, cue weights were stable throughout the experiment; when cues were uncorrelated, contextual cues were down-weighted. Listeners thus can re-weight cues based on their statistical structure. Studies failing to account for re-weighting risk over/under-estimating cue importance.

Fig. 1.

Experimental design. (A) General experimental paradigm. (B) Between-participant manipulation of the correlation (and thus conflict) between the two cues.

Fig. 2.

Proportion of tent-responses by VOT, context, and group, averaged across the experiment. Error bars are bootstrapped 95% confidence intervals (CIs) over subject means.

Fig. 3.

Effect of lexical context across trials for each conflict group, as determined by GAMM analysis. Bands are 95% GAMM-derived CIs. Predictions were computed at the average VOT value. The wide CIs for the beginning of the experiments are a consequence of log-transforming trial (fewer observations enter those CIs). The estimated variance of participants' responses did not vary across trials (Figures S1 and S2 in the supplementary material) (footnote 2).

Fig. 4.

(Color online) Effect of VOT across trials (note the log scale) for each conflict group, as determined by GAMM analysis. Light gray (green online) corresponds to earlier trials and dark gray (red online) to later trials. While there was a numerical trend for the slope of the categorization curves to decrease over the course of the experiment, this effect was not significant.