Notes: Precursors to morality in development
How children develop a sense of right and wrong starts with a mix of brain activity, social surroundings, and how they act. This study looked at 73 babies and toddlers between and months old. It used different ways to measure things, like brain scans (EEG/ERP), watching where they look (eye-tracking), tasks they did, and what their parents thought about right and wrong. The goal was to see how early they judged social situations (like good or bad actions) and if this connects to their moral feelings later on. They used two main tests that didn't ask the children directly but watched their natural reactions: a "social evaluation task" (SET) where someone was helping or hurting, and a "Chicago moral sensitivity task" (CMST) with actions that were either kind or unkind.
All children's brains showed a difference when they saw kind actions versus unkind actions. This was seen in brain wave patterns (EEG power) and specific brain responses (ERPs). How much their brains differed in these responses helped predict if they preferred kind characters. These brain differences were also shaped by what parents valued about fairness. This means that a child's sense of right and wrong likely grows from general brain functions (like paying attention or wanting to approach/avoid things) combined with their social experiences.
Neural measures and paradigms
The study used brain scans (EEG/ERP), eye-tracking, and measurements of brain activity when the children were resting. They used two main tests to secretly check how children judged good and bad actions:
SET (Social Evaluation Task): They looked at specific brain wave patterns (5–8 Hz power and activity in the front part of the brain) when children watched someone hindering (hurting) or helping. They also tracked how long children looked at the different actors. Afterward, a reaching task showed if children openly preferred the helper.
CMST (Chicago Moral Sensitivity Task): This test had 70 short videos (some kind, some unkind actions). They measured specific brain responses (ERPs) during different time periods: early (200–300 milliseconds after seeing the action), middle (300–500 milliseconds), and late (600–1,000 milliseconds). Certain brain signals like Nc (middle window) and PSW/LPP (late window) showed whether the processing was automatic (quick, unconscious) or more controlled (thoughtful).
Important details about how they did the study: they used 17 sensors for EEG brain waves, measured resting brain activity for 4 minutes, and continuously tracked eye movements. The children were between and months old. They looked at brain activity differences between the left and right front of the brain both at rest and during tasks, along with the strength of the ERP brain responses.
Behavioral findings
Behavior in the SET task: When children were asked to pick between a helper and a hinderer, their choices were just by chance (about half picked the helper, half picked the hinderer, out of 54 children). The child's age didn't affect who they picked. When it came to sharing toys, there were different results: out of about 54 children, 15 shared both toys, 11 shared their favorite toy, 7 shared a toy they didn't like as much, 4 shared a toy without a clear favorite, and 34 didn't share at all. The child's age also didn't predict if they would share.
Child's personality and parent's feelings: Children who were better at effortful control (like being able to wait or control their impulses) were more likely to share. However, being energetic (surgency) or easily upset (negative affect) didn't link to sharing or preferring the helper/hinderer. Parents who were good at understanding others' feelings (perspective taking) had children who shared more. But parents who often felt personal distress had children who shared less.
Neural temporal dynamics and individual differences
CMST brain response patterns (ERPs): Between 300 and 500 milliseconds after seeing an action, kind scenes caused a stronger brain response in the back-middle part of the head (parietal sites like Cz/Pz) compared to unkind scenes. There was no clear difference very early (200–300 milliseconds). Later on (600–1,000 milliseconds), there was also no strong difference between kind and unkind scenes in the front or back of the brain after accounting for age.
Differences between children: Children whose brains showed a bigger difference between helping and hindering actions in the CMST (both the 300–500 ms and 600–1,000 ms time windows) were more likely to prefer kind characters. This link was strongest in the front part of the brain (e.g., F4 in the middle window, a strong connection with ; P < 0.001).
Parent's role: How much parents cared about unfairness to others predicted how much their babies' brains reacted differently to kind vs unkind actions in the CMST, specifically between 300 and 500 milliseconds (e.g., at Cz, a moderate connection with , P < 0.05). This link wasn't seen in the later 600–1,000 ms brain response window.
Parental dispositions and parent–child value transmission
Parents' desire for justice and their ability to understand others' thoughts (cognitive empathy) were connected to how children's brains processed information early on and how much children shared. Parents who cared more about justice had children with bigger brain differences in the early CMST task (meaning their brains reacted more strongly to moral differences). Parents who were better at cognitive empathy had children who shared more.
The study suggests how this might happen: parents might teach their children directly, or their home environment might shape the child's experiences, or it could be a mix of genes and environment. These results show a close, early connection between what parents value and how a child's brain responds to moral situations, as well as their sharing habits.
Resting-state findings and domain-general mechanisms
Brain activity differences when the children were resting (5–8 Hz frontal asymmetry) did not predict if they would pick the helper or share. Also, brain activity differences in the front of the brain during the SET task did not predict picking the helper or sharing. This suggests that early social judgments use general brain functions, like paying attention, managing brainpower, or wanting to approach/avoid things. These general functions are then specifically tuned by the social situation.
The brain activity differences in the front of the brain (both at rest and during tasks) match what other research found: more activity on the left side of the front brain is linked to wanting to approach things or feeling positive, while more activity on the right side is linked to wanting to withdraw or feeling negative. However, these links to judging social situations only appeared in certain parts of the tasks, not all the time.
Temporal interpretation and developmental implications
Babies and toddlers' brains show early differences in how they react to kind and unkind actions. This means that the basic ways our brains figure out right from wrong start even before children can think clearly about morality.
The way the brain processes these actions—first with quick, automatic responses (Nc, 300–500 ms) and then with more thought-out, controlled responses (PSW/LPP, 600–1,000 ms)—fits with ideas that moral development comes from a mix of fast emotional reactions and slower thinking.
The values passed from parents to children seem to affect how children's brains respond early on, and these responses then influence their behaviors, like sharing, during their second year of life.
Methods (participants and procedures)
Who was in the study: There were 73 children, all between and months old (average age was about 18.7 months; 37 were girls). Their parents agreed to let them participate, and the families were paid. The children came to a lab for tests, which included brain scans (EEG/ERP), watching their eyes, measuring brain activity at rest, and doing small activities.
What was measured: For the children, they looked at their temperament (how energetic they were, if they were easily upset, and if they could control themselves). For parents, they used surveys to see how sensitive they were to injustice and how well they understood others' feelings (empathy and perspective taking). Brain activity at rest was recorded using a quick, standard method. The SET and CMST tasks were done using 17 EEG sensors on the scalp, and eye movements were tracked at the same time. A sharing game with two toys was used to see how kind the children were.
How they did it: Parents filled out surveys about their attitudes before the testing session. Children then completed the SET task, had their resting brain activity measured, did the CMST task, and played a sharing game, all in one visit. Eye-tracking information was gathered throughout these tasks.
Implications and takeaways
These findings suggest that a child's early judgments about right and wrong come from a changing combination of general brain systems and what they learn from their social world, especially from their parents' values.
Specific brain patterns (like differences in activity in the front of the brain, early Nc signals, and later PSW/LPP changes) are linked to how children see social actions and how they later act in kind ways, like sharing.
What parents value about justice and how well they understand others' thoughts (cognitive empathy) play a role in how their children's brains develop and how they behave. This points to possible ways to help children become more kind and prosocial from an early age.
Overall, this study offers a way to combine brain data, behavior, and environmental factors to understand how morality develops. This has important lessons for how we think