Finding phrases: On the role of co-verbal facial information in learning word order in infancy

Abstract

The input contains perceptually available cues, which might allow young infants to discover abstract properties of the target language. Thus, word frequency and prosodic prominence correlate systematically with basic word order in natural languages. Prelexical infants are sensitive to these frequency-based and prosodic cues, and use them to parse new input into phrases that follow the order characteristic of their native languages. Importantly, young infants readily integrate auditory and visual facial information while processing language. Here, we ask whether co-verbal visual information provided by talking faces also helps prelexical infants learn the word order of their native language in addition to word frequency and prosodic prominence. We created two structurally ambiguous artificial languages containing head nods produced by an animated avatar, aligned or misaligned with the frequency-based and prosodic information. During 4 minutes, two groups of 4- and 8-month-old infants were familiarized with the artificial language containing aligned auditory and visual cues, while two further groups were exposed to the misaligned language. Using a modified Headturn Preference Procedure, we tested infants' preference for test items exhibiting the word order of the native language, French, vs. the opposite word order. At 4 months, infants had no preference, suggesting that 4-month-olds were not able to integrate the three available cues, or had not yet built a representation of word order. By contrast, 8-month-olds showed no preference when auditory and visual cues were aligned and a preference for the native word order when visual cues were misaligned. These results imply that infants at this age start to integrate the co-verbal visual and auditory cues.

Fig 1. Shared structure of the two artificial languages.

The table represents the basic shared structure of the two ambiguous artificial languages: (a) the categories and tokens of the languages, (b) the two possible parses of the ambiguous stream, (c) the 8 test items. On the right, a picture of the animated line drawing.

Fig 2. Graphical depiction of the alignment of prosodic and visual information in the aligned and misaligned conditions.

The brackets signal the duration of the head nods, while the arrows depict the location of their peak.

Fig 3. Graphical depiction of the study’s modified HPP (image adapted from [6]).

The size of the lights as they appear on the drawing of the screen is scaled to the actual size displayed on the 46” screen during the study.

Fig 4. Looking time results.

The x axis shows the four groups examined. The y axis displays the infants’ looking times in seconds. The dark grey bars depict looking times to the frequent-initial items, and the light grey bars looking times to the frequent-final items. Error bars represent the standard error of the mean.