IB Psychology SLTopic 2 — Human DevelopmentPaper 1 & 2Cognitive approach~11 min read
Theory of Mind: Understanding Other Minds
You do something extraordinary hundreds of times a day without noticing: you work out what someone else is thinking, and you allow for the fact that they might be wrong. Children cannot do this at first. Watching the moment they learn to is one of the neatest things in psychology.
📘 What you need to know
Theory of mind (ToM) is the ability to recognise that other people have their own thoughts, feelings, beliefs and knowledge, which may be different from yours.
Intentionality is a key part of it: understanding that people act because of what they believe and want.
ToM is usually well developed by about 3 or 4 years old, though signs of early intentionality appear much sooner.
Some researchers propose a theory of mind module (ToMM), a brain system that matures at around 4.
ToM is tested with false belief tasks: can the child accept that someone else believes something untrue?
The two classic tasks are the Smarties test and the Sally-Anne task (Baron-Cohen et al., 1985).
ToM research has been used to explore social difficulties in autism, though that account is debated.
What theory of mind gives you
It is called a “theory” because you can never actually see inside someone’s head. You build a working model of what they probably think, based on what they have seen, said and done — and then you use that model to predict them.
Here is intentionality in action. Your friend picks up an umbrella. You instantly conclude they think it will rain. You did not check the forecast; you read their belief off their behaviour. That is theory of mind doing its job.
Definition
Theory of mind = understanding that other people have mental states of their own — and that those states can be different from yours, and can be wrong.
A child without theory of mind assumes everyone knows what they know. That single assumption is what every false belief task is designed to expose.
False belief tasks
A false belief task sets up a situation where one person has out-of-date information. To pass, the child has to ignore the truth they can see and answer from inside someone else’s head.
🧩 The Smarties test, step by step
Show a sweet tube and ask the child what is inside. They say sweets, because that is what the packet says.
Open it and reveal that it actually contains pencils. The child is now the one who knows.
Ask the false belief question: what will your friend outside think is inside the box?
“Sweets” = pass. The child understands the friend has not seen inside and will be wrong.
“Pencils” = fail. The child assumes everyone knows what they know. This is egocentric thinking.
Baron-Cohen and colleagues (1985) used this task, and the pattern of answers became one of the most repeated findings in developmental psychology.
Watch the wording in the exam. The question is “where will Sally look“, not “where is the marble”. Children who answer “the box” are answering a different question — the one about reality rather than the one about belief.
Theory of mind and autism
The Sally-Anne task has been widely used to explore why some autistic children find reading other people harder. Baron-Cohen’s proposal was that difficulties with theory of mind might explain part of that.
Be careful how you write about this. It is one explanation, not a definition of autism, and plenty of autistic people pass false belief tasks. Treat it as a research finding with real limitations, not as a description of a whole group of people.
A useful piece of nuance. Failing a false belief task does not prove that ToM is absent. The task also needs memory, attention and quite a lot of language. A child might understand Sally perfectly and still fail because they lost track of the story.
Evaluating theory of mind research
Strengths
Limitations
Simple and repeatable. The tasks are short, standardised and have been run thousands of times with consistent results.
May lack validity. The tasks demand memory and language, so a child can fail while still having theory of mind.
Practical applications in education, including anti-bullying work, since bullying often exploits ToM skills.
Contradictory evidence. Pretend play needs ToM, and some children who fail the tasks pretend perfectly well.
Improved understanding of autism and led to social skills training programmes.
No agreement on how ToM develops — maturation, general cognitive growth, or learning through interaction.
Gives a clear behavioural measure of something as slippery as understanding another mind.
Culture-biased. Most studies use Western, individualistic samples where individual viewpoints are emphasised.
Link to concepts
Bias: ToM research is mostly Western. In collectivist settings, children may be taught to think about the group first, which could change both how ToM develops and how it is measured.
Causality: with autism, it is unclear which way the arrow points. Less social interaction means less practice at reading people — but weaker ToM could also make social interaction harder. The direction is unresolved.
Measurement: a single pass or fail cannot capture a skill that develops gradually and depends on the situation.
Exam practice
EXAM QUESTION
Explain how theory of mind is investigated. [9]
This is a method question. Describe the procedure precisely, then explain why that procedure tells you anything.
Define first
ToM = understanding others hold mental states that can differ from your own and can be false.
Explain the logic of a false belief task
Set up a situation where one character has out-of-date information, then ask the child to predict that character.
Describe one task in fullSally-Anne: marble in basket → Sally leaves → Anne moves it to the box → “where will Sally look?”Explain what each answer shows
“Basket” = the child separates Sally’s belief from reality. “Box” = the child assumes Sally knows what they know.
One limitation of the method
The task also loads memory and language, so failure does not prove ToM is missing.
Method + reasoning + one criticismdescribe the procedure like a recipe: steps in order, no gaps
💡 Exam tips
Use the phrase false belief. It is the technical term and examiners look for it.
Give the tasks in correct order. Getting the sequence wrong makes the whole explanation collapse.
Say what a pass and a fail look like. The contrast is where the understanding shows.
Link ToM back to Piaget’s egocentrism if the question allows — they are two ways of describing the same limitation.
Write about autism carefully and tentatively. “May help explain some difficulties” is accurate; “autistic people have no theory of mind” is not.
Keep the validity criticism ready: the task measures memory and language as well as ToM.
⚠ Common mix-ups
Confusing theory of mind with empathy. ToM is knowing what someone thinks. Empathy is feeling what they feel. You can have one without the other.
Answering the wrong question in Sally-Anne. It asks where Sally will look, not where the marble actually is.
Saying ToM appears suddenly at 4. It develops gradually, and early signs of intentionality appear in infancy.
Treating failure as proof of absent ToM. The task has other demands built into it.
Overstating the autism link. It is a contested explanation for some difficulties, not a defining feature.
Getting the Smarties answers backwards. “Sweets” is the pass, because that is what the uninformed friend will think.
Up next: Bowlby and the Roots of Attachment — we switch from how children think to who they become, starting with the first relationship any of us ever has.
Want this explained one-to-one?
Book a free session with an experienced IB Psychology tutor and get your trickiest topics made simple.
