The AI "Trolley Problem": Using eye tracking to reveal children's moral development

Based at the Cognition and Human Behavior Key Laboratory of Hunan Province at Hunan Normal University, Associate Professor Yan Zhiqiang and his team have dedicated themselves to studying the connection between children’s cognition and social behavior. 

The moral dilemma of the human-robot era 

As the use of service robots grows, the team has shifted its focus to studying how morality works in a world with humans and robots coexisting. Their goal is to understand how people, especially children in key developmental stages, see robots and the moral values assigned to them. 

Previous studies have shown that adults often display obvious “speciesism” when making sacrificial decisions: they prioritize human life above all else. But is this moral preference innate, or is it learned through socialization? Do preschoolers demonstrate a different decision-making pattern than adults when faced with life-and-death choices involving robots and humans? 

Eye tracking in the trolley problem 

In a study published in Cognitive Development, the team used a 2 (age) × 4 (condition) mixed design to examine the effects of age and different "victim-survivor" combinations on moral judgment. The researchers recruited 72 participants in China, including 36 preschoolers (around 6 years old) and 36 adults. The experiment involved presenting various moral dilemma scenarios, where participants had to make a choice and subsequently rate the ethical acceptability of that choice on a seven-point Likert scale. 

To go beyond behavioral responses, the team used Tobii Pro Fusion screen-based eye tracker to record eye movements during decision-making. Unlike behavioral results on their own, eye tracking captures the visual search path and attention distribution before a decision is made. Professor Yan believes that eye tracking data reveals how much attention is given to different "species" (humans vs. robots), thereby decoding the cognitive processing behind moral judgments. 

Utilitarian children vs. pro-human adults 

The results showed apparent age differences. In conflict situations involving humans and robots, adults exhibited a strong "pro-human" bias, rarely choosing to sacrifice humans to save robots, and made decisions quickly. In contrast, preschoolers displayed a greater tendency toward "utilitarianism", prioritizing the number of lives saved, even when that choice involved sacrificing a human to save robots. 

Eye tracking data clarified these behavioral results with greater detail. Preschoolers showed significantly longer first fixation times and total fixation times than adults during the decision-making. This indicates that when faced with cross-species moral dilemmas, children need more cognitive effort to evaluate their options and have not yet developed the firm (or stereotyped) "human-first" schema seen in adults. Additionally, the longer fixation time on the victim area by preschoolers may reflect a higher level of concern for the potential victim. 

Furthermore, the study found a negative correlation between empathy and utilitarian decisions or moral acceptability. Regression analysis revealed that higher empathy levels were associated with a greater tendency to favor certain species during moral judgment. 

Empowering a future of human-robot co-existence 

Based on Tobii eye tracking data, Professor Yan's team suggests that human preference for their own species ("speciesism") might not be entirely innate but could be reinforced over time through internalized social norms. The observed "equality" and "utilitarianism" in children offer a new perspective on the course of moral development. 

About the lab 

Using high-precision eye tracking equipment like Tobii Pro Fusion, the Cognition and Human Behavior Key Laboratory of Hunan Province systematically explores the human mind — from basic cognition and language processing to child development. The lab focuses on transforming these foundational research findings into scientific evidence that supports education, mental health, and human-robot interaction in the age of smart technology. 

References 

Zhou, K., Chen, M., Xu, H., Cao, Y., & Yan, Z. (2024). Preschoolers prioritize humans over robots less than adults do: An eye-tracking study. Cognitive Development, 72, 101505.