A research team from Kyoto University in Japan reported in the latest issue of the American online science journal PLOS ONE that children around three and a half years old already possess the ability to "read faces"—inferring what others are thinking by observing their expressions. This finding indicates that developing the skill to interpret facial expressions takes time and represents an important breakthrough in understanding how humans acquire cognitive abilities.
Japanese Study Discovers Three-Year-Olds Possess Remarkable Face-Reading Skills (Public Health Network)
While it was previously known that infants frequently observe adult faces, the exact age at which children begin to interpret others' mental states like adults remained unclear.
Previous studies indicated that children aged 4 to 4.5 years develop the ability to infer others' mental states through language. A research team led by Masako Akiwa, a professor at Kyoto University's Graduate School, hypothesized that children likely acquire the ability to infer others' mental states through visual cues at an earlier age.They showed two videos to 15 adults in their twenties, 16 children averaging 3.5 years old, and 16 one-year-olds. The videos depicted pouring juice into a cup (predictable behavior) and intentionally spilling juice onto a table (unexpected behavior). Special equipment tracked their gaze, comparing how long they focused on the characters' expressions.
Results showed that 1-year-olds consistently focused on the actor's face. In contrast, 3.5-year-olds directed their gaze toward the actor during both pouring and spilling actions. After pouring, their gaze shifted to the actor's face, but following the spill, they spent significantly more time observing the face—a tendency nearly identical to adults, albeit with a smaller time difference between the two behaviors.
The research team concluded that observing the unexpected action of spilling juice onto the table heightened children's focus on facial expressions. This indicates they consciously inferred the actor's mental state to understand the cause. This experiment demonstrates that humans acquire the ability to comprehend others' thoughts through facial expressions within three to four years of birth. While infants frequently observe adults' faces, this behavior may serve to attract attention and enhance survival prospects, reflecting a different purpose.