Improving the robustness of infant lexical processing speed measures

Julia Egger,Christina Bergmann,Caroline F Rowland

doi:10.3758/s13428-020-01385-5

Julia Egger, Christina Bergmann + Show 1 more

Open Access

https://doi.org/10.3758/s13428-020-01385-5

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Abstract

Visual reaction times to target pictures after naming events are an informative measurement in language acquisition research, because gaze shifts measured in looking-while-listening paradigms are an indicator of infants’ lexical speed of processing. This measure is very useful, as it can be applied from a young age onwards and has been linked to later language development. However, to obtain valid reaction times, the infant is required to switch the fixation of their eyes from a distractor to a target object. This means that usually at least half the trials have to be discarded—those where the participant is already fixating the target at the onset of the target word—so that no reaction time can be measured. With few trials, reliability suffers, which is especially problematic when studying individual differences. In order to solve this problem, we developed a gaze-triggered looking-while-listening paradigm. The trials do not differ from the original paradigm apart from the fact that the target object is chosen depending on the infant’s eye fixation before naming. The object the infant is looking at becomes the distractor and the other object is used as the target, requiring a fixation switch, and thus providing a reaction time. We tested our paradigm with forty-three 18-month-old infants, comparing the results to those from the original paradigm. The Gaze-triggered paradigm yielded more valid reaction time trials, as anticipated. The results of a ranked correlation between the conditions confirmed that the manipulated paradigm measures the same concept as the original paradigm.

Highlights

Studying the language of children and infants is challenging
The looking-while-listening paradigm can be used to do more than determine whether an infant understands a word: It can be used to study the dynamics of infant’s sentence processing, which can inform theories of how and why, not just when infants acquire different linguistic skills
The speed with which young infants orientate their eyes to look at a familiar object in response to a label—so-called lexical speed of processing— predicts new vocabulary growth

Summary

Introduction

Studying the language of children and infants is challenging. Even though infants and children comprehend utterances early on, taking measures that tell us what they understand can be difficult. If. the looking-while-listening paradigm can be used to do more than determine whether an infant understands a word: It can be used to study the dynamics of infant’s sentence processing, which can inform theories of how and why, not just when infants acquire different linguistic skills. The speed with which young infants orientate their eyes to look at a familiar object in response to a label (e.g., look at the dog)—so-called lexical speed of processing— predicts new vocabulary growth. This finding has stimulated a number of suggestions about the relationship between familiar word processing and novel word learning.

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