Exploring Infant Sensitivity to Visual Language using Eye Tracking and the Preferential Looking Paradigm

Summary

Eye tracking studies using a preferential looking paradigm can be used to study infants' emerging understanding of, and attention to, their external visual world.

Abstract

We discuss the use of the preferential looking paradigm in eye tracking studies in order to study how infants develop, understand, and attend to the world around them. Eye tracking is a safe and non-invasive way to collect gaze data from infants, and the preferential looking paradigm is simple to design and only requires the infant to be attending to the screen. By simultaneously showing two visual stimuli that differ in one dimension, we can assess whether infants show different looking behavior for either stimulus, thus demonstrating sensitivity to that difference. The challenges in such experimental approaches are that experiments must be kept brief (no more than 10 min) and be carefully controlled such that the two stimuli differ in only one way. The interpretation of null results must also be carefully considered. In this paper, we illustrate a successful example of an infant eye tracking study with a preferential looking paradigm to discover that 6-month-olds are sensitive to linguistic cues in a signed language despite having no prior exposure to signed language, suggesting that infants possess intrinsic or innate sensitivities to these cues.

Introduction

The paramount goal of developmental science is to study the emergence of cognitive functions, language, and social cognition in infants and children. Eye movements are modulated by participants' intentions, comprehension, knowledge, interest, and attention to the external world. Collecting oculomotor responses in infants while they orient to and scan visual static or dynamic images can provide information about infants' emerging understanding of, and attention to, their external visual worlds and the language input they receive.

While eye tracking technology has been around for more than a hundred years, it has only recent....

Protocol

The following procedure, which involves human participants, was approved by the Human Research Protections Program at University of California, San Diego.

1. Participant screening and preparation

1. Recruit infants in the defined age range of interest (e.g., 5 to 14 months old). Use multiple methods, including social media, flyers, postal mail. Consider making agreements with local hospitals or governmental offices to retrieve records listing newborns, their parents, and their mailing addresses, allowing to reach out directly to them via postal mail.
2. Screen the infants when interested parents call the lab for scheduling. ....

Results

The sample in Stone, et al.⁷ consisted of 16 younger infants (mean age = 5.6 ± 0.6 months; range = 4.4-6.7 months; 8 female) and 13 older infants (mean age = 11.8 ± 0.9 months; range = 10.6-12.8 months; 7 female). None of these infants had seen sign language before. First, we assessed for differences in total looking time between age groups, and found no significant difference (Means: 48.8 s vs. 36.7 s; t(27) = 1.71; p = 0.10). This rules out the possibility of extraneous age-related expl.......

Discussion

We used the preferential looking paradigm to discover evidence that infants may be sensitive to a particular visual cue in the language signal, despite having no prior experience with signed language. Furthermore, this sensitivity was observed only in younger infants, and not older infants, a manifestation of the classic perceptual narrowing function. Evidence of an age-based preference for well-formed syllables based on sonority restrictions allowed us to further hypothesize that sonority may be an important cue for inf.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Eye Tracker	Tobii		Model X120
Experiment Presentation & Gaze Analysis Software	Tobii		Tobii Studio Pro
Experimenter Monitor	Dell		Dell Professional P2210 22" Wide Monitor
Stimulus Monitor	Dell		Generic 17" Monitor
CPU	Dell		Dell Precision T5500 Advanced with 2.13 Ghz Quad Core Intel Xeon Processor and 4 GB DDR3 Memory) with 250 GB SSD hard disk and standard video output cards.
Webcamera	Logitech		Logitech C150 HD Cam
Video Capture Card	Osprey		Osprey 230 Video Capture Card (to capture stimulus that is output to Stimulus Monitor)