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Updated: Sep 23, 2026
Exploring Infant Sensitivity to Visual Language using Eye Tracking and the Preferential Looking Paradigm
Published on: May 15, 2019
Comparison between grating acuity measured by visual tracking and preferential looking in infants
1Department of Strabismus and Neuro-Ophthalmology, St.Gallen, Kantonsspital, Switzerland.
Insights
Visual tracking is a valid method for infant visual acuity testing, though it yields lower results than preferential looking due to attention demands.
Area of Science:
- Ophthalmology
- Developmental Neuroscience
- Pediatric Vision
Background:
- Assessing visual acuity in infants is crucial for early detection of visual impairments.
- Traditional methods may be limited by infant cooperation and attention span.
Purpose of the Study:
- To compare visual acuity measurements obtained through visual tracking and preferential looking in infants.
- To determine the validity and reliability of visual tracking as an infant visual acuity assessment tool.
Main Methods:
- Fifty-one healthy full-term infants (3-93 days old) were tested.
- Visual acuity was measured using infrared photo-oculography for visual tracking (smooth and saccadic pursuit) and preferential looking with grating cards.
- Stimuli for visual tracking involved moving gratings (0.1-1.6 cycles/degree) at a constant velocity.
Main Results:
- A significant correlation (p < 0.05) was found between visual acuity measured by visual tracking and preferential looking.
- Visual acuity determined by visual tracking was consistently lower than that determined by preferential looking in infants up to 14 weeks of age.
Conclusions:
- Visual tracking is a valid method for assessing infant visual acuity.
- Lower visual acuity values obtained via visual tracking may be attributed to the requirement for sustained infant attention.
Background:
The aim of this study was to compare the visual acuity measured by visual tracking and by preferential looking.
Methods:
We examined 51 healthy full-term infants between three and 93 days of age. Visual acuity was tested with two different methods. One method was visual tracking (smooth and saccadic pursuit), recorded with an infrared photo-oculographic technique. For stimulation of visual tracking a square of 9.4 degrees of visual angle with vertical gratings (0.1, 0.2, 0.4, 0.8 and 1.6 cycles per degree) moved at a constant velocity of 7.5 degrees/sec. for 38 sec. on a surface of equal luminance. The other method was preferential looking, determined by a second examiner, where we used plates with vertical gratings (0.1, 0.2, 0.4, 0.8, 1.6, 3.2 and 6.4 cycles per degree).
Results:
The comparison of the two methods shows a significant correlation (p < 0.05). Visual acuity determined by visual tracking is lower than the acuity determined by preferential looking in the first 14 weeks of age.
Conclusion:
Our study shows that visual tracking is a valid method for visual acuity testing in infants. The need of sustained attention is a possible reason for the lower values in comparison with the acuity determined by preferential looking.
