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Updated: Dec 13, 2025
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Published on: May 15, 2019
Orientation Effects in the Development of Linear Object Tracking in Early Infancy
Diana S Y Tham1, Alison Rees2, J Gavin Bremner2
1Edgehill University.
Insights
Six-month-old infants show improved oculomotor tracking for oblique trajectories, enabling object persistence perception. Four-month-olds struggle with oblique paths, impacting their understanding of object permanence.
Area of Science:
- Developmental Psychology
- Cognitive Neuroscience
- Infant Vision
Background:
- Infant oculomotor tracking skills develop rapidly.
- Tracking accuracy is poorer for combined horizontal and vertical movements.
- Object persistence emerges at 4 months but is initially absent for oblique trajectories.
Purpose of the Study:
- To investigate infant eye movement accuracy for different trajectory orientations.
- To determine if improved tracking supports object persistence for oblique paths.
- To compare tracking abilities in 4-month-old and 6-month-old infants.
Main Methods:
- Recorded eye movements of 64 infants (32 4-month-olds, 32 6-month-olds).
- Infants tracked objects moving along horizontal, vertical, and oblique trajectories.
- Two experiments were conducted, including trials with temporary object occlusion.
Main Results:
- Infants tracked oblique trajectories less accurately than horizontal or vertical ones.
- Six-month-olds demonstrated significantly improved tracking accuracy compared to 4-month-olds.
- Six-month-olds' accuracy on oblique paths matched 4-month-olds' accuracy on linear paths.
Conclusions:
- Four-month-olds' oblique trajectory tracking may be insufficient for object persistence.
- Six-month-olds' enhanced tracking accuracy supports object persistence perception across all trajectory types.
- Age-related improvements in oculomotor control are crucial for developing object permanence understanding.
Abstract:
Infants' oculomotor tracking develops rapidly but is poorer when there are horizontal and vertical movement components. Additionally, persistence of objects moving through occlusion emerges at 4 months but initially is absent for objects moving obliquely. In two experiments, we recorded eye movements of thirty-two 4-month-old and thirty-two 6-month-old infants (mainly Caucasian-White) tracking horizontal, vertical, and oblique trajectories. Infants tracked oblique trajectories less accurately, but 6-month olds tracked more accurately such that they tracked oblique trajectories as accurately as 4-month olds tracked horizontal and vertical trajectories. Similar results emerged when the object was temporarily occluded. Thus, 4-month olds' tracking of oblique trajectories may be insufficient to support object persistence, whereas 6-month olds may track sufficiently accurately to perceive object persistence for all trajectory orientations.
