The Role of Single Talker Acoustic Variation in Early Word Learning

Abstract

Recent work has demonstrated that the addition of multiple talkers during habituation improves 14-month-olds’ performance in the switch task (Rost & McMurray, 2009). While the authors suggest that this boost in performance is due to the increase in acoustic variability (Rost & McMurray, 2010), it is also possible that there is something crucial about the presence of multiple talkers that is driving this performance. To determine whether or not acoustic variability in and of itself is beneficial in early word learning tasks like the switch task, we tested 14-month-old infants in a version of the switch task using acoustically variable auditory stimuli produced by a single speaker. Results show that 14-month-olds are able to learn phonemically similar words within the switch task with increased acoustic variability and without the presence of multiple talkers.

Notes

¹ An intriguing alternative is that talker variability helps when the stimuli are phonetically similar, as in Rost and McMurray (2009) but hinders when it is more variable. This currently remains untested as work with adults such as Mullennix and Pisoni (1990) had not examined phonetically similar items.

² The Rost and McMurray (2009) control experiment, unlike prior single-talker switch task experiments, used a single exemplar of each word. As a result there was no variation to measure. Thus we recorded new control items to simulate how standard versions of the switch task would work.

³ Looking times are generally right-tailed, violating the normality assumptions of ANOVA, however an ANOVA run on log-transformed looking times revealed comparable effects.

Additional information

Funding

This research is supported by NIH grant DC008089 to Bob McMurray.