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Effects of Reinforcement Learning on Gaze Following of Gaze and Head Direction in Early Infancy: An Interactive Eye‐Tracking Study

01. March 2021

A study by Christine Michel, Ezgi Kayhan, Sabina Pauen and Stefanie Höhl.

As a baby, you discover the world anew every day with all your senses. How do babies manage to find their way in a world full of smells, sounds and new impressions? They often orient themselves to their fellow human beings and concentrate on the things in their environment that are also important for other people. In doing so, they often use the line of sight of another person and look at the things that other people are looking at.

This behaviour is called “gaze-following behaviour” in research.
We took a closer look at this gaze-following behaviour in the current study, which was published in the journal “Child Development” in January 2021:
Do babies as young as four months old follow the gaze of others?
Do they follow the eye movements or head turn of that person? And can we reinforce this behaviour if babies are rewarded for their gaze-following behaviour?

In several studies, we showed 99 babies on a screen looking sideways at a woman. She looks at a cartoon mouse and averts her gaze from another cartoon mouse.
We measured whether the babies looked longer at the cartoon mouse the woman was looking at. To learn more about where the babies looked, we used computer-based eye tracking.

We found out that babies as young as four months follow the direction of the woman’s head and gaze and look at the mouse for longer periods of time, but only if the woman also moves her head in this direction. If she only moves her (small) eyes and keeps her (large) head directed forward towards the baby, the babies looked at both mice for the same length of time.
So the rather large movement of the head seems to be helpful for gaze-following behaviour in four-month-old babies.

And what role does reward play in this? In a second phase of the study, we rewarded the babies for following the woman’s gaze direction. If they looked at the cartoon mouse that the woman was looking at, the mouse began to wiggle.
We could tell that the children found this exciting from their pupils: they were larger when the mouse moved than when it stood still, which in this case indicates positive excitement and interest.
However, the children did not reinforce their behaviour afterwards, i.e. they looked at the mice for the same length of time after this reward experience as before.

Babies as young as 4 months use other people’s head direction to direct their attention to things in the environment that are also important to other people. So the babies in our study already showed the gaze-following behaviour.

An open research question remains whether they can learn to follow the gaze of other people via reward at an even younger age (for example, at two – three months) in order to better find their way in their environment.

Dr. Christine Michel, Post-Doc, AG Haun

Madlen Bartholmeß
Phone +49 (0) 341 97 31 870