The behavior of babies is impacted by the example set by their parents – but not always in the way expected.

Infants who have anxious mothers fixate on threats around then, according to behavioral experiments presented by a team from Penn State in the journal Emotion.

“(Our) results support a growing literature suggesting that attention bias toward threat is present in early development,” write the scientists, primarily of the Penn State Cognition, Affect, and Temperament Lab. “Attention bias toward threat was positively related to maternal anxiety.”

The lab looked at the babies’ fixation on certain faces, using German eye-tracking technology.

The 98 children, aged between 4 and 24 months, were presented with happy, neutral, or angry faces. Their gaze was followed even as they were presented with a distraction in their peripheral vision, according to the paper.

The amount of time spent looking at the faces despite the distraction was measured down to the level of milliseconds, according to the study.

(The group of 98 had been pulled from a group of 238. About 100 had to be discounted because the children were distressed or fussy at the time of the laboratory visit. Others didn’t complete the task, because they got distracted).

The times that were considered valid were cross-referenced with a group of surveys and questionnaires completed by the mothers. These self-evaluations included those on child behavior and maternal anxiety, as reported in the findings.

The age factor did not appear to change the results of the experiments, according to the researchers. That would indicate that the mothers’ anxiety was not training the children to fixate on the angry faces or negative stimulus, accordingly.

However, Koraly Pérez-Edgar, the associate professor of psychology at Penn State who led the team, said the nurture-nature divide was not perfectly clear.

Although the main driver of the fixation on angry faces appears to be inherited genetically, there could be more to come, she said.

“There is likely a biological component to the child’s response to the world around them,” Perez-Edgar told Laboratory Equipment magazine. “At the same time, I would caution that is it not solely biological.”

Further work by Perez-Edgar and her team involves larger data samples and different tasks for the children – and some differences with age are beginning to appear, she said.

Perez-Edgar and her team have previously published on infant behaviors at the earliest stages of life, including a study last fall that indicated that infants who were more shy and reluctant to try new thing were more at risk of anxiety at older ages.

A colleague from Rutgers University was also involved in the current work.