Executive function as a common functional component of false belief tasks

Mental states are desires, percepts, beliefs, knowledge, thoughts, intentions, feelings, etc. They play a causal role in behaviour; I don’t go to get some chicken because it’s in the fridge, but because I believe it’s in the fridge and desire it. I’ll still go to the fridge if the chicken’s not there. We automatically infer mental states from people’s behaviour. This is incredibly adaptive, permitting prediction of other people based on what one knows about their beliefs and desires. Any theory of how we acquire these mentalising capabilities would have to explain children’s normal and abnormal development. Some investigators argue that young children's failures on false-belief and other theory-of-mind tasks are due to more domain-general information processing problems, e.g. the inability to inhibit a dominant, ready-to-go response.

Young children fail to understand other people will act on false beliefs. In the Sally-Ann task, Sally puts an object in box X and then departs. Ann moves the object to box Y during Sally’s absence. When Sally returns, the question to the child is: Where will Sally search for the object-in X or in Y? Most 4-year olds say X, 3 year olds say Y. It seems to be quite a profound problem, e.g. even if Sally says, “I think it’s in X”, they still respond she thinks it’s in Y. In general there’s a developmental transition around 3/4.

They not only have problems with other people’s false beliefs, but also their own. In the smarties task, an experimenter shows a 5-year-old a smarties tube and asks her what she thinks is in it. "Smarties," she replies. Then the child gets to look inside and discovers that it actually contains pencils, not smarties. The experimenter then asks her what another child who had not yet seen inside the tube would think it contained. "Smarties," the child answers. The experimenter tries the same procedure with a 3-year-old. The response to the initial question is the expected "smarties," but the response to the second is "pencils." Even more surprising is that in response to further questioning, the 3-year-old claims that she had initially thought that there were pencils in the tube and had even said that there were. You get the same results with autistic people.

3 to 5 ½ year olds were tested on false belief, forward digit span (taxing the auditory loop) and backward digit span (taxing the central executive). Backward digit span was a significant predictor of false belief understanding. False belief understanding correlates with dual task performance: naming three objects while counting them, e.g., "one is a doll, two is a car, three is a spoon") or naming the objects while finger tapping. This suggests that the relationship between false belief understanding and working memory depends on the central executive component of working memory.

Executive inhibition consists of representing the existence of the interfering action tendency in order to inhibit that tendency. The false belief task is mastered at the same time as executive inhibition tasks, e.g. after imitating the experimenter's hand shape children had to switch to doing the opposite shape.

Experimenter: flat hand - fist - flat hand -...

Child: fist - flat hand - fist -...

The natural tendency to imitate interferes with what one is supposed to do. In order to inhibit this natural tendency you can’t just concentrate more on the proper task because the task involves concentrating on what the experimenter does. Automatic inhibition of irrelevant stimuli doesn’t work and executive inhibition is needed. Another example is: the ability to give correct answers in the false belief task correlates with the ability to suppress pointing to where an object is in favour of pointing to where it is not. Children were trained to point to one of two opaque containers one of which contained a sweet. If it contained the sweet the opponent consumed it. If the container was empty the child got to eat the sweet. This taught the child to point to the empty container. After 15 such trials containers with windows on the child's side were introduced, so that the child (but not the opponent) could see which container was baited. Most 3 year olds pointed to the full container. Most of them kept pointing there for up to 20 test trials. They do better if they’re asked to mislead the other person (autists don’t), or use an arrow.

Children’s understanding of if-if-then conditionals correlates with performance on the false belief tasks. By the age of 2½ years children can sort according to a single criterion, e.g., put things that look the same together. However, they have problems sorting according to two rules, e.g., "put the car in group A and the flowers in group B". By about 3 years children can do this, but not until about 4 can they switch sorting rules, e.g.

Sort by colour: the blue flower goes with the blue car and the green car goes with the green flower

Sort by shape: the blue flower goes with the green flower, and the green car goes with the blue car

This task also qualifies as an executive function task since the antecedent sort-by-colour response interferes with the sort-by-shape response.

It’s been suggested that the false belief task itself is an executive function task requiring the inhibition of a predominant response, namely to answer with the object's real location. This however is unlikely, because in the explanation version of the false belief task the child observes Sally look in the wrong cupboard and is asked to explain why she did so. Children who do not understand false belief tend to say nothing, which means there is no interfering answer that needs to be inhibited.

This begs the question, is theory-of-mind necessary for executive function? Or is executive function necessary for theory-of-mind? 3½ years or 4½ years children with autism are not particularly executive function impaired in relation to an age and IQ matched control group. Over the next years the control group gets better at executive function while the children with autism do not improve so that by 5½ years there is a clearly identifiable executive function gap between controls and autists. Other disorders associated with executive dysfunction (obsessive-compulsive disorder, Tourette's syndrome, attention deficit with hyperactivity disorder…) do not necessarily result in autism. There are also cases where children did better on executive function than on false belief. This data speaks against executive components in theory-of-mind tests and doubly embedded conditionals as accounts for the observed developmental relationship between theory-of-mind and executive function performance. This implies theory of mind is either necessary for executive control or common brain regions.

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