IB Psychology HLTopic 2 — Models of DevelopmentPaper 1 & 2Cognitive approach~9 min read
Theory of Mind: Understanding Other Minds
There is a moment in early childhood when a child works out something enormous: other people have their own thoughts, and those thoughts can be wrong. Before that moment, a child assumes everyone knows whatever they know. After it, lying, teasing, surprises and secrets all become possible.
📘 What you need to know
Theory of Mind (ToM) is the ability to recognise that other people have their own mental states — thoughts, feelings, beliefs and knowledge — that may differ from your own.
Intentionality is a key part of it: understanding that people act on their own beliefs, so you can predict what they will do.
ToM is thought to be fully developed by around 3 or 4 years old, though some research suggests infants of 7–9 months already show early intentionality.
Some researchers argue for a biological basis: a theory of mind module (ToMM) maturing at around four years of age.
It is tested with false belief tasks — the Smarties test and the Sally–Anne task (Baron-Cohen et al., 1985).
The Sally–Anne task has been used to explore links between ToM difficulties and autistic spectrum disorder (ASD).
Evaluation words: validity, no consensus, culture bias, cause or consequence.
What ToM actually gives a child
Theory of Mind is not mind reading. It is the working assumption that other people have a head full of their own stuff, and that their stuff is not identical to yours.
Definition to learn
Theory of Mind = the ability to attribute mental states — beliefs, desires, knowledge and intentions — to other people, and to understand that these may differ from your own.
Once you have it, you can predict behaviour without being told anything. You see a friend pick up their green coat and reach for the lead, and you know the dog is about to be walked. You are reading their intention from their action.
Watch a three-year-old play hide and seek. They cover their own eyes and think they have hidden. That is ToM not yet online: if I cannot see you, you cannot see me. A year or two later the same child hides properly, because now they can imagine what you can see.
False belief tasks
To test ToM you need a situation where a child knows something that another person does not. If the child can hold both pictures in mind at once — what is true, and what the other person believes — they pass.
Panel 4 is the whole test. The marble really is in the box — but Sally never saw it move, so a child with ToM says she will look in the basket.
🧩 The Smarties test, step by step
Present the box — show a child a Smarties box and ask what they think is inside. They say “Smarties”.
Reveal the surprise — open it. It contains pencils.
Ask the false belief question — “what will your friend think is inside?” The friend has not seen inside.
Score it — “Smarties” is a pass: the child understands others can hold a false belief. “Pencils” is a fail: the child assumes everyone knows what they know, which is egocentric thinking.
Both tasks share one design trick. The child is given knowledge that another person does not have. Passing means keeping two versions of reality apart — the true one and the other person’s one.
Theory of Mind and ASD
The Sally–Anne task has been used to explore links between ToM difficulties and autistic spectrum disorder, offering one possible account of why some autistic children find it harder to read other people’s perspectives.
Be careful how you word this. The research shows an association on a particular task — it does not mean autistic people have no understanding of other minds, and the direction of the relationship is genuinely unresolved.
Evaluating theory of mind research
Strengths
Practical applications. ToM research has informed anti-bullying strategies. Bullies often use ToM skills to manipulate others, so interventions can put the same insight to positive use.
Better understanding of ASD. The work has led to training programmes designed to build children’s social skills.
Simple, standardised tasks. False belief tasks are quick, repeatable and easy to score, so they can be used across large numbers of children.
Limitations
Validity problems. The tasks need memory and language as well as ToM, so a child may fail because they lost track of the story, not because they lack ToM.
Contradictory evidence. Pretend play requires ToM, and some children who fail the task manage pretend play perfectly well — which suggests the task is underestimating them.
No consensus on how ToM develops. It may develop alongside general cognitive ability (Piaget’s view) or be internalised through interaction with adults (Vygotsky’s view). That disagreement makes ToM difficult to test cleanly.
Link to concepts
Bias — much ToM research is culture-biased, based mainly on Western, individualistic samples. In collectivist cultures, enculturation may encourage group-oriented thinking rather than individual perspective-taking, so more research within those cultures is needed for cultural relativism.
Causality — with ASD it is unclear whether ToM difficulties are a cause or a consequence. Children may have fewer chances to practise ToM if they avoid social interaction; alternatively, ToM difficulty may underlie the social difficulty. The direction remains unresolved.
Exam practice
WORKED EXAMPLE
Explain one method used to test theory of mind. [3 marks]
1. Name the task
The Sally–Anne false belief task (Baron-Cohen et al., 1985).
2. Procedure in one breath
Sally hides a marble in her basket and leaves; Anne moves it to her box; the child is asked where Sally will look.
3. Interpretation“Basket” = pass — the child understands Sally holds a false belief. “Box” = fail, showing egocentric thinking.
Name + procedure + interpretationSay that Sally does not see the marble move. Without that, the task makes no sense.
WORKED EXAMPLE
Evaluate research on theory of mind. [ERQ paragraph]
Strength
False belief tasks are standardised and easy to replicate, so findings are reliable across large samples.
LimitationHowever they also demand memory and language, so failure may not mean the child lacks ToM.
Supporting point
Pretend play requires ToM, and some children who fail the task still engage in it.
Judgement
The tasks are a reliable measure of something — but possibly not purely of theory of mind.
Reliable is not the same as validThat last line is a proper evaluation sentence. Learn the shape of it.
💡 Exam tip
Always define ToM before using it. One clean sentence at the start protects every mark after it.
Know both tasks. If a question bans the one you prepared, the other saves you.
The word intentionality is worth a mark on its own if you explain it with an example.
Use the Piaget versus Vygotsky disagreement as your “no consensus” evaluation point — it links three pages of this topic together.
Write about ASD carefully and respectfully. Say “difficulties on this task”, not “cannot understand others”.
Reliability and validity are not the same thing. False belief tasks score high on one and are questioned on the other.
⚠️ Common mix-up
ToM is not empathy. ToM is knowing what someone thinks; empathy is feeling what they feel.
Pass and fail reversed. In Sally–Anne the pass is “basket”. In Smarties the pass is “Smarties”. Both times the pass is the wrong answer about reality.
Do not say ToM appears suddenly at four. Early intentionality has been reported at 7–9 months; four is when the full ability is usually in place.
The ToMM is a proposal, not a proven brain structure. Write “has been proposed”.
Egocentrism here is Piaget’s term reused. Same idea, different task — useful to point out, not to confuse.
Failing a false belief task does not diagnose anything. Never write as if the task is a test for autism.
Up next: Bowlby and the Roots of Attachment — we move from how children come to understand other minds to the very first relationship that shapes them.
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