Summary: What makes us uniquely human? For decades, scientists have debated whether our capacity for language and our ability to understand other people’s thoughts and feelings (Theory of Mind) arise from the same neural origins. New research using functional MRI (fMRI) in very young children provides clear evidence that these two advanced cognitive abilities develop from separate, non-overlapping brain systems.
Scanning children as young as three years old, researchers found that language and Theory of Mind recruit distinct regions within the superior temporal lobe and show unique patterns of connectivity with the rest of the brain. These findings indicate an early, discrete neural architecture for speech and social cognition rather than a single, shared source that differentiates later in development.
Key Facts
- Hemispheric separation: Both functions are anchored in the superior temporal lobe, but they are lateralized: language processing is concentrated in the left hemisphere while Theory of Mind activity is located in the right.
- No developmental overlap: Contrary to theories proposing that children’s brains start undifferentiated and later specialize, the study shows that by age three these regions are already distinct and non-overlapping.
- Connectivity fingerprints: Resting-state fMRI revealed unique connectivity profiles for each region. These “fingerprints” demonstrate that the language and mentalizing systems communicate with different brain networks.
- Stable wiring across childhood: Longitudinal tracking of the same children over time showed consistent separation of these systems, indicating the distinction is part of the brain’s baseline blueprint rather than a maturational outcome.
- Adult integration: Although the regions are separate in children, adults show greater cross-network communication, suggesting that later in life we increasingly coordinate language and social cognition during complex social behavior.
Source: Ohio State University
New evidence shows two key human communication skills—language and Theory of Mind—have distinct neural origins in young children, matching patterns seen in adults.
The research challenges the idea that language and social reasoning share a common neural origin during development. Instead, the brain appears to be wired early with specialized circuits: one set dedicated to linguistic processing and another to understanding others’ mental states. Using task-based and resting-state fMRI, investigators demonstrated both functional separation and distinct connectivity patterns for these systems in young children.
Researchers measured brain activity while participants listened to spoken sentences to engage language regions and watched a silent cartoon designed to elicit mentalizing for Theory of Mind. In control conditions, participants heard nonsensical speech for the language task and observed scenes of physical pain that elicit affective responses but not mental-state inference for the ToM task. The study used high-resolution voxel-level imaging to compare activation across hemispheres.
“It appears these processors that support speaking and those that support mentalizing were dissociated very early in development,” said Zeynep Saygin, senior author and associate professor of psychology at The Ohio State University. “We don’t find traces of overlap in children, which suggests an evolved division of labor rather than a later developmental splitting.”
The team first replicated adult findings in 28 adults, confirming separate, stimulus-responsive regions for language and Theory of Mind in the superior temporal lobe. They then scanned 42 children ages 3 to 9 across 54 sessions, collecting task and resting-state data. Results showed clear, non-overlapping activation for the two domains even at the earliest ages tested.
Beyond localization, the researchers examined each region’s resting-state connectivity pattern—a “connectivity fingerprint”—to identify how it communicates with other brain areas. Predictive modeling showed that the fingerprints for language and Theory of Mind are distinct, reinforcing the conclusion that these systems operate through different neural networks from early childhood.
Longitudinal data strengthened the claim that separation is stable: connectivity profiles measured at one time point predicted future task activation almost identically, indicating minimal developmental reorganization in these networks during childhood. However, comparisons with adults revealed increased interaction between networks later in life, consistent with the idea that adults more frequently integrate language and social cognition in complex social tasks.
“Children’s brains show distinct functional specialization for these skills, and while adults’ networks become more interactive, the early separation suggests distinct neural origins,” said Kelly Hiersche, the study’s lead author.
Funding: Supported by the U.S. National Science Foundation, the Alfred P. Sloan Foundation, the National Institutes of Health, and Ohio State University (College of Arts and Sciences, Center for Brain Injury Recovery and Discovery, Women in Philanthropy award).
Key Questions Answered:
A: Not necessarily. This research shows language and Theory of Mind rely on distinct brain systems, so a delay in one domain does not automatically imply a delay in the other.
A: They use stories where characters hold false beliefs or are unaware of events (for example, a character searches for a toy where they last saw it). To predict or explain the character’s behavior, viewers must infer the character’s mental state, engaging mentalizing processes.
A: Adult social interactions are often more complex, requiring us to combine language and empathy. Increased cross-network communication in adults likely reflects greater integration of these complementary skills during everyday communication.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff to clarify methods and implications.
About this theory of mind and neurodevelopment research news
Author: Emily Caldwell
Source: Ohio State University
Contact: Emily Caldwell – Ohio State University
Image: The image is credited to Neuroscience News
Original Research: Open access. “Functional dissociation of language and theory of mind in the developing superior temporal lobe” by Kelly J. Hiersche, David E. Osher & Zeynep M. Saygin. Communications Biology. DOI: 10.1038/s42003-026-10040-2
Abstract
Functional dissociation of language and theory of mind in the developing superior temporal lobe
Language and theory of mind (ToM)—the ability to infer others’ mental states—are essential for human communication, yet their developmental neural origins have been debated. Do these functions occupy distinct, oppositely lateralized regions within the superior temporal lobe (as in adults), or do they arise from shared substrates that later differentiate?
This study examined functional specificity and connectivity fingerprints in children ages 3–9 (n = 42 subjects, 54 sessions) and adults (n = 28). Children exhibited distinct neural responses for language and ToM in the superior temporal lobe, mirroring adult organization, with no evidence of a developmental phase where the systems overlapped. Connectivity fingerprints that predict later task activation were nearly identical to concurrent patterns and largely non-overlapping across domains. While both systems continue to specialize toward the adult state, they are largely distinct early in development, supporting separate neural origins for language and social cognition.