Imagine you’re out for drinks with a group of friends on a Friday night. It’s been a long week at work, but you’re excited to let your hair down and relax. As it approaches midnight, you hit the dance floor, feeling energized by the music and the atmosphere. The last thing you want to think about is going home. 

After a while, you notice that one of your friends is yawning and regularly checking the time on her phone. You presume she’s feeling tired and thinking about calling a cab home. 

At that moment, you’re using Theory of Mind. You recognize that your friend has different internal states; she’s tired, perhaps bored or uncomfortable, while you’re still buzzing and having fun. You’re inferring her thoughts and desires based on subtle cues, and acknowledging that her experience of the same situation differs from your own.

Theory of mind is the ability to understand that other people have their own thoughts, beliefs, desires, intentions, and perspectives that are different from our own. It’s what enables us to predict how others will think, feel, and react in a given situation. 

Theory of mind isn’t something we’re born with. Many argue that it starts forming at around 3-5 years old and fully develops into adolescence and even early adulthood.¹ Some psychologists, such as Andrew Meltzoff, have suggested that the theory of mind has its origins even earlier, at 15 months.⁴ This is when children are imitating other humans around them nonverbally, and they start making connections between the visible world of others and their own internal states and feelings. 

The ability to attribute mental states, particularly beliefs and desires, to other people and to understand that their behavior is guided by these mental states, is an essential part of children’s cognitive development. In individuals with neurodevelopmental conditions, such as autism spectrum disorder, theory of mind is often delayed or impaired. Understanding things like pretending, thinking about “what if” situations, knowing how to take turns in play, sharing attention with someone else, and realizing that words can cause actions (like making a promise or giving a command) can be especially difficult for people with developmental differences, compared to their neurotypical peers.⁵ Interestingly, theory of mind has been used to illuminate the mysteries of autism, but at the same time, the disorder has profoundly shaped our understanding of social cognition and theory of mind.⁴

False Belief Task: A common psychological test used to see if someone (usually a child) can understand that another person can believe something that isn’t true. One of the most common of these tests is the Sally-Anne task, which was developed in the mid-1980s by Simon Baron-Cohen, Alan Leslie, and Uta Frith.

Neurotypical and Neurodivergent: "Neurotypical" refers to people whose brain functions align with societal norms. "Neurodivergent" refers to people whose brains work differently from these expectations, such as those with autism or ADHD. 

Alexithymia: A condition where someone has difficulty identifying and describing their own emotions.

Second-Person Relationship: A direct, face-to-face interaction in which people engage with each other emotionally and socially, not through detached observation, but through real-time connection.

fMRI (Functional Magnetic Resonance Imaging): A brain scanning method that shows which parts of the brain are active during different mental tasks.

Opacity Doctrine: A cultural belief, common in some societies like Vanuatu, that it’s inappropriate or impossible to know what another person is thinking.

Mindblindness: A term used to describe difficulty in understanding others' mental states. Originally developed by Simon Baron-Cohen, it’s often linked to autism research.

The first mention of the term ‘theory of mind’ was back in 1978, but it wasn’t used in relation to humans but chimpanzees. In their study, David Premack and Guy Woodruff (both from the University of Pennsylvania) presented a chimpanzee with videos of a human struggling to solve problems—like trying to get to an out-of-reach banana—and observed whether the chimp seemed to understand the human’s goals.³ They argued that the chimp’s behavior suggested an understanding of the human’s intentions, opening up the possibility that non-human animals might possess a basic form of what we now call the theory of mind.

Although the term was new, the idea that humans have a unique ability to attribute mental states to others was centuries old. Philosophers such as René Descartes and later Ludwig Wittgenstein spent much time pondering the nature of self-awareness, consciousness, and the challenge of understanding the inner lives of others. Famously quoting ‘I think, therefore I am,’ Descartes’ mind-body dualism had a strong influence on the way we understand ourselves and the people around us.¹⁴ However, it wasn’t until the 1970s and 80s that psychologists began developing methods to study this capacity empirically.

Theory of mind was also part of a broader shift away from Jean Piaget’s 1936 theory of child cognitive development.⁴ The Swiss psychologist believed that young children are egocentric—not in a selfish way, but in the sense that they struggle to take other people’s perspectives.⁶ According to his theory, children in the preoperational stage (around 2 to 7 years) are unable to understand that others might have thoughts, beliefs, or knowledge that differ from their own. He argued that true perspective-taking and the ability to reason about other people’s mental states only begin to develop in the concrete operational stage, around seven years old or later. Yet research in the last couple of decades of the 20th century blew apart this theory and showed that young children know more at a much earlier age.⁴

So what happened in the field of developmental psychology to completely overturn the theory of one of the world’s most famous child psychologists? Following the chimpanzee experiment, researchers in the field of developmental psychology started to apply Premack and Woodruff’s ideas to understand how children come to understand that others can hold beliefs that are different from their own. This led to the development of the false belief test, such as the famous Sally-Anne task, which revealed that children typically begin to grasp false beliefs—an essential aspect of theory of mind—around the age of four.

Developed in 1985 by Simon Baron-Cohen, Alan Leslie, and Uta Frith, the Sally-Anne task examines a child’s ability to understand that other people can believe things which are not true.⁷ In the task, a child watches as two dolls, Sally and Anne, are introduced. Sally places a marble in her basket and then leaves the scene. While she is away, Anne moves the marble from the basket into her own box. When Sally returns, the child is asked, “Where will Sally look for the marble?” A child who understands false belief will answer “in the basket,” recognizing that Sally does not know the marble has been moved. A child who has not yet developed this understanding will typically answer “in the box,” assuming that Sally knows what the child knows.⁸

At around the same time, the Sally-Anne test was developed, and the theory of mind gained particular attention in relation to autism spectrum disorder. Baron-Cohen, for example, showed that many children on the autism spectrum struggle with theory of mind tasks and perform poorly on the false belief test. This led to the development of the influential (and still debated) idea that a “mindblindness” or difficulty in attributing mental states to others might underlie some of the social and communication challenges associated with autism.¹⁰ By the end of the 20th century, the theory of mind was seen by many as the one theory to explain all autism traits. 

Eventually, the theory of mind in autism studies was largely abandoned.⁹ But in the last decade or so, it’s had somewhat of a renaissance. Rather than throwing the baby out with the bathwater, scientists now see theory of mind as one component of a multifaceted understanding of autism. 

fMRI studies have shown that in classic false-belief tasks, the brain activity of autistic and non-autistic people looks surprisingly similar. This challenges the idea that autistic people use completely different brain areas to solve such tasks. So why do people with autism show such different results on false belief tests to their neurotypical counterparts?

Some scientists think other factors, like alexithymia—difficulty identifying one’s own emotions—might affect these false-belief task results.¹² Others believe that the theory of mind isn’t one single skill, but a set of different abilities, and that autistic people may struggle with some of them but not others.¹¹ Because autism is so varied, it’s unlikely that any one test will capture how theory of mind works for all autistic individuals. Instead, researchers argue that we need more flexible approaches that can reflect individual differences in how people think and communicate.

Indeed, advancements in medical imaging technology, especially fMRI, have had a huge influence on research into the theory of mind across a wide range of fields. For example, we are now able to see which parts of the brain are responsible for our cognitive abilities, which is related to the theory of mind. fMRI studies have shown that specific brain areas—like the temporoparietal junction, medial prefrontal cortex, and posterior cingulate cortex—consistently activate when people think about others’ thoughts and beliefs. This technology has also been used to see how theory of mind in people with certain psychiatric disorders, such as psychosis, differs from that of those who don’t have them.13

Jean Piaget

Swiss psychologist known for his pioneering work in child development and cognitive psychology. Piaget proposed a stage-based theory of cognitive development, emphasizing how children actively construct knowledge as they grow. 

David Premack

American psychologist best known for his research on animal cognition and the development of the “Premack Principle.” He co-authored the seminal 1978 paper that introduced the term theory of mind in studies of primate behavior.

Guy Woodruff

American cognitive scientist who co-authored the foundational 1978 paper with David Premack that introduced the concept of theory of mind, based on experiments with chimpanzees interpreting human intentions.

Simon Baron-Cohen

British clinical psychologist and professor of developmental psychopathology. He is widely known for his work on autism and theory of mind, including the development of the Sally-Anne test and the “mindblindness” theory.

Alan Leslie

British cognitive scientist whose research has focused on early childhood development, particularly the mechanisms behind the theory of mind. He developed models of how infants begin to understand mental states.

Uta Frith

German-born developmental psychologist recognized for her influential research on autism, dyslexia, and theory of mind. She helped introduce the false-belief task to autism research and emphasized the cognitive basis of social understanding.

The ability to understand that others have beliefs, desires, and intentions that differ from our own has a significant impact across many areas of life. Not only does it enable us to interact socially with others, develop relationships, and predict others’ behaviors, but it also helps us navigate school, work, and other situations.  

Childhood Development 

Understanding other people’s thoughts and feelings has a big impact on how children connect and communicate with others.²⁴ Theory of mind helps them take part in conversations, play games, work through disagreements, and build friendships, both at home and at school. It also plays a key role in how kids develop a sense of right and wrong. For example, things like feeling embarrassed, blushing, or getting teased all rely on being able to imagine what someone else is thinking.

Theory of mind also helps children build trust with others and recognize when someone is being honest or not. In fact, learning to deliberately deceive someone, keep a secret, or spot when someone is hiding the truth are some of the earliest signs that a child is starting to develop a theory of mind.²³

Academic Outcomes

Research suggests that the theory of mind impacts children’s educational experiences, particularly during middle childhood.¹⁵ Serena Lecce and Rory Devine from the Universities of Pavia and Birmingham, respectively, argue that the theory of mind doesn’t just support our social interactions, but also plays a key role in academic success. Based on existing research, the authors provide evidence to suggest that children who are better at reasoning about mental states tend to have stronger reading comprehension skills. This is because they can better infer characters’ intentions and grasp underlying meanings in texts. Importantly, the relationship between theory of mind and reading comprehension is bi-directional—as the former improves, so does the latter, and vice versa. 

The correlation between theory of mind and academic achievement is also present in deaf and hard-of-hearing students. Theory of mind is often delayed in children with hearing loss due to limited access to language.¹⁷ A study by academics in Poland followed 270 deaf and hard-of-hearing children, starting at around age 7, to see how their ability to understand other people’s thoughts and feelings related to how well they did in school.16 The children were tested three times, 10 months apart, on their theory of mind skills and their language and math abilities. The researchers found that the relationship went both ways: the children with stronger theory of mind skills tended to do better in school later on, and those who were doing well in school also showed better growth in their theory of mind skills. 

Understanding mental illness

People with schizophrenia often struggle to recognize their own mental health challenges, and may also have difficulty understanding what others are thinking or feeling. Research suggests that these two issues may be more closely connected than they seem.

One study looked at how the theory of mind of people with schizophrenia—a serious mental health condition associated with hallucinations, delusions, psychosis, and disorganized thinking and behaviors—relates to their ‘insight,’ or awareness of having a mental illness. The researchers worked with 193 people diagnosed with schizophrenia or schizoaffective disorder. In one task, participants were asked to infer what someone really meant during social conversations; i.e., reading between the lines. They also conducted tests to measure how aware the participants were of their mental health condition. The study found that people who were better at understanding others’ intentions were also more likely to recognize that they had a mental health issue. That is, the better developed an individual’s theory of mind, the greater awareness of their schizophrenia. 

The most prominent controversies related to the theory of mind are focused on autism, and in particular, the harmful narratives that have developed concerning autistic people and their perceived lack of empathy. However, over the years, criticism has also been levied against the original theory of mind studies and the conceptual errors on which the research is based.²² 

Cracks in the autism theory

Back in the 1990s, Baron-Cohen and his colleagues suggested that difficulty with theory of mind is a core feature of autism. For a long time, this was the main theory used to explain the social challenges experienced by people with autism. During this period, the same scientists found that autistic people seemed to be less adept at interpreting people’s states of mind, particularly in terms of ascribing emotion to facial expressions.⁹ Eventually, in 2004, Baron-Cohen updated his theory of “mindblindness” and proposed that autism is an “empathy disorder.” In doing so, he also suggested that the theory of mind is part of the larger skill of empathy. 

However, the idea that autistic people lack empathy eventually started to receive backlash. Some researchers and people in the autistic community have suggested that the idea has contributed to harmful stereotypes about autism.¹⁸ Quite the opposite, many autistic people argue that they are too empathetic and in touch with other people’s emotions. Baron-Cohen has repeatedly defended his theory, emphasizing that while autistic people have difficulty with reading emotions and mental states, they still have other forms of empathy.

In addition to this backlash, researchers began to notice problems with theory of mind tests, especially in how well they reflect real-life social understanding.⁹ Early studies were small and inconsistent, and many autistic people who struggle socially still passed these tests. In fact, theory of mind performance in autistic individuals is highly variable and often overlaps with that of non-autistic people, depending on factors like communication ability and test format.²⁰ And as clinical psychologist Erin Libsack points out, how well someone performs on a test doesn’t always match how they behave in real-world situations, like in school or at the playground.¹⁹ Additionally, results weren’t always stable over time—people’s scores on theory of mind and empathy tests could change.9 However, despite these criticisms, the view that autistic people “lack” a theory of mind continues to dominate psychology and public opinion. 

The hidden mind

Some have argued against the philosophical assumptions behind the theory of mind, particularly the idea that understanding others involves “reading” hidden mental states through theoretical reasoning. Australian psychoanalyst, Michael Plastow, for example, argues that this view treats the mind as a kind of private, internal space that we must infer from outward behavior.²¹ However, Plastow and other psychologists believe this approach is unrealistic and alienating, and that real human interaction doesn’t actually rely on this kind of detached, cognitive analysis of other people. Instead, our understanding of others comes from direct (face-to-face), embodied, and emotional engagement with them, what philosophers call a second-person relationship. From this perspective, the theory of mind creates an artificial distinction between our “inner” mental life and “outer” behavior that doesn’t represent how we really interact with others around us.

How does theory of mind develop across cultures? 

Western psychology affirms that the theory of mind develops between 3 and 5 years of age. However, psychology and behavioral science tend to be WEIRD—Western, Educated, Industrialized, Rich, and Democratic. What about cultures in non-Western countries? How does theory of mind develop in children who aren’t growing up in industrialized, Western hemisphere societies? 

Researchers from Australia and New Zealand traveled to the small island nation of Vanuatu to understand how the development of theory of mind might differ depending on culture, language, and environment.²⁵ They tested over 400 ni-Vanuatu children, aged 3 to 14, from urban areas (like the capital Port Vila) and rural communities on different islands. Children were given a series of tasks designed to measure different aspects of theory of mind, such as false belief tasks, emotion-related tasks, and tasks involving desires, beliefs, and knowledge access. The researchers compared how children from different areas performed, and they also looked at how the language used in testing (local language vs. national creole) might affect the results. 

The researchers found that children in Vanuatu, especially in rural areas, showed a significant delay in theory of mind development. The watershed for passing these tasks wasn’t until seven years old, and in some cases, not even by adolescence.

So what did they make of these results? This delay, the researchers argue, doesn’t mean that Vanuatu children lack a theory of mind. Instead, it reflects cultural differences in how people talk about and think about minds. In many parts of the Pacific, including Vanuatu, it’s considered inappropriate to speculate about what others are thinking. This belief is known as the opacity doctrine. As a result, children grow up in environments where talking about thoughts, beliefs, and intentions is less common, especially in conversations with adults. Social understanding in these communities is more likely to be based on emotions and actions, rather than explicit talk about beliefs.

Research like this underscores the importance of not over-relying on evidence that solely comes from Westernized societies. When we do this, we are basing our theories on findings from a tiny proportion of humanity, leading to skewed or even erroneous conclusions. 

Theory of mind in animals? 

Humans may not be the only mammals to have a theory of mind. As we’ve already seen, chimpanzees were the original subjects of theory of mind research, and elephants have also been shown to exhibit behaviors that might be linked to this cognitive ability. This includes recognizing themselves in a mirror, trying to help other animals that are hurt or disabled, and paying special attention to the bodies of animals that have died.² Scrub jays have also shown theory of mind behaviors, such as moving and re-hiding their food caches if they know they were being watched while hiding them.²⁶ 

But do non-human animals really have a theory of mind, or are they just reacting to observable cues? In other words, how can we tell if an animal is “mind reading” or “behavior reading?”

Elske van der Vaart and Charlotte Hemelrijk believe that evidence of theory of mind in non-human animals is far from conclusive. They have three main concerns with evidence in this area. First, the experiments may be flawed. Animals can often succeed in tasks without needing to understand minds, simply by reacting to patterns or learned cues. Second, many studies are not well-controlled, failing to rule out simpler explanations. And third, there’s a bias in interpretation. Both scientists and the public are often eager to see human-like thinking in animals, which may lead to over-interpreting their behavior. This is particularly true for great apes like chimpanzees, who share 98.8 percent of their DNA with humans—why wouldn’t they also have a theory of mind like us? 

Rather than trying to understand if animals that can’t speak to us can or can’t read minds, van der Vaart and Hemelrijk believe we should be exploring how sophisticated an animal’s social reasoning is. We may actually find out that animals don’t think about others’ minds in exactly the same way humans do, rendering the theory of mind completely redundant. 

Psychological Theories 

Theory of mind is just one explanation of human mental processes and behaviors. In this article, we look at Jean Piaget’s Cognitive Development Theory and other influential frameworks that have shaped how we understand the human mind. 

Functionalism

Functionalism is a philosophical perspective that considers mental states in terms of their functional roles rather than their internal constituents. This article explores how mental processes, like beliefs and desires, are understood through their causal relations to behavior and other mental states. This perspective aligns with your exploration of how understanding others' mental states influences behavior, a key component of the theory of mind.

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