Do gestures help people understand speech in noise when they can also see the speaker's mouth?

Details

Younger and older adults benefit from seeing a speaker's mouth when understanding speech in noise, and younger adults also benefit from iconic hand gestures that accompany speech. Researchers investigated how much both age groups benefit from seeing both the mouth and these gestures, and whether working memory and inhibitory control influence that benefit.

In an experimental word recognition task, 28 younger and 28 older adults encountered three visual contexts: the mouth blurred (speech-only), visible speech, or visible speech plus iconic gesture. The speech was either clear or embedded in multitalker babble. There were also two visual-only conditions: visible speech, and visible speech plus gesture.

Both age groups were more accurate when both visual cues were present than when either one or neither was present. Older adults gained significantly less than younger adults, although the groups performed equally well in speech-only and visual-only word recognition. Individual differences in verbal working memory and inhibitory control partly accounted for age-related performance differences.

The researchers concluded that seeing iconic gestures alongside visible speech improves both younger and older adults' comprehension of speech in noise, but that the benefit of this additional visual information is modulated by age and verbal working memory. Future research must establish whether the findings extend beyond the single-word level.