Learning word order at birth: A NIRS study

Abstract

In language, the relative order of words in sentences carries important grammatical functions. However, the developmental origins and the neural correlates of the ability to track word order are to date poorly understood. The current study therefore investigates the origins of infants' ability to learn about the sequential order of words, using near-infrared spectroscopy (NIRS) with newborn infants. We have conducted two experiments: one in which a word order change was implemented in 4-word sequences recorded with a list intonation (as if each word was a separate item in a list; list prosody condition, Experiment 1) and one in which the same 4-word sequences were recorded with a well-formed utterance-level prosodic contour (utterance prosody condition, Experiment 2). We found that newborns could detect the violation of the word order in the list prosody condition, but not in the utterance prosody condition. These results suggest that while newborns are already sensitive to word order in linguistic sequences, prosody appears to be a stronger cue than word order for the identification of linguistic units at birth.

Keywords: Near-infrared spectroscopy; Newborn infants; Prosody; Word order.

Fig. 1

The design of Experiments 1 and 2.

Fig. 2

Probe placement as shown on a schematic head and on a newborn doll model.

Fig. 3

The grand average results of Experiment 1. The x axis represents time in sec. The y axis shows concentration change in mmol × mm. The curves indicate grand average responses for standard (oxyHb: continuous red line, deoxyHb: continuous blue line) and deviant blocks (oxyHb: dashed pink line, deoxyHb: dashed turquoise line). The rectangle along the x axis indicates time of stimulation. Asterisks indicate channels with a statistically significant advantage for the deviant over the standard blocks in oxyHb (red asterisks) and deoxyHb (blue asterisks) concentration change. The ROIs obtained through the permutation test in the left hemisphere (LH) and the right hemisphere (RH) respectively are encircled using dotted lines. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 4

The average responses to standard (light grey) and deviant (dark grey) blocks in the LH and RH in the first two (blocks 1–2) and the last two (blocks 23–24) blocks of Experiment 1, illustrating potential habituation effects throughout the time course of the experiment.

Fig. 5

The grand average results of Experiment 2. Plotting conventions are the same as in Fig. 3.

Fig. 6

The average responses to standard (light grey) and deviant (dark grey) blocks in the LH and RH in the first two (blocks 1–2) and the last two (blocks 23–24) blocks of Experiment 2, showing a habituation effect.