MODULAR HYPOTHESIS AS TO THE DEVELOPMENT OF CHILDREN’S REPRESENTATIONS OF THE PROPOSITIONAL ATTITUDES OF AGENTS

Theory of mind is the ability to infer mental states in others from behaviour and to predict behaviour from these mental states. Such a theory enables the child to explain observable events (people’s actions) by postulating unobservable mental states.

According to modular theory, we represent mental states as attitudes that agents have towards propositions [1], e.g. consider the proposition, “it’s raining”. I could, hope that… believe that…+proposition. We exploit such about mental state-representations (or metarepresentations) when we say,

Maxi believes that the chocolate is in the box

or that

Maxi's brother wants the chocolate

or that

Mommy is pretending that the banana is a telephone.

Modularity theorists believe that young children acquire through neurological maturation innate, domain-specific systems, Theory of mind mechanisms, which are functional specialisms for making explicit information about (1) agents and the goal directed actions they produce, and (2) "about mental states-representations", which represent only propositional attitudes of agents and their role in producing behaviour. These modules are not strictly modular in terms of being like the fast sensory systems relatively resistant to conceptual interference. Elements of the information processing are accessible to conscious awareness and intentions, knowledge and desire can moderate the results. They do, however, operate through conceptual primitives and inference algorithms. Although experience may be necessary to trigger the operation of these mechanisms, it does not necessarily determine their nature. 

In Leslie’s model three cognitive mechanisms help the child’s developing concepts of agency.

First to develop is the infant’s ability to distinguish agency. Infants respond differently to people than they do to objects and seem to expect people to behave differently than objects do. 5-8-week-old babies imitate mouth openings and tongue protrusions produced by an adult but not similar-looking behaviours produced by an object. From 2-4 month-old infants will seek face-to-face interaction and evidence turn taking. From 4-8 months an infant will show an interest in objects; primary intersubjectivity. At around 6 months infants detect eye direction. Infants look longer at a face that’s looking at them. From 6 months there’s physiological arousal when eyes look at you. Infants try to retrieve a just-disappeared object by reaching toward its place of disappearance but try to retrieve a just-disappeared person by vocalizing to the person. They act more surprised when an inanimate object seems to move entirely on its own, with nothing pushing it, than when a person does.

According to Leslie this occurs because a “Theory of Bodies mechanism” that looks for agency develops early in the first year. The infant is predisposed to expect certain types of movement characteristic of agents, e.g. the more an object changes motion state by itself and not as a result of external impact, the more likely it is that it is an agent. In Baron-Cohen’s model, the crucial perceptual feature used by the infant to distinguish agents is the presence of eyes. The "Eye Direction Detector" computes the direction of the agent’s gaze.

Infants do a variety of things that reflect a dawning awareness of intentionality, using communicative gestures to get you to do something and checking to see whether their attempts have succeeded, e.g. looking at, pointing to, holding up, or vocalizing about an object, following another person's direction of gaze. At 5 months infants who were habituated to a person grasping a particular object dishabituated more strongly to a change in goal object than to a change in the grasping movement. Between 9 and 12 months children expect a person looking at an object to manipulate that object and not another object. 12-month-olds expect a person to reach for an object that the person is looking at with positive affect rather than for another one to which the person is not attending. From 8-16 months we see the infant engaging in and then initiating acts of joint visual attention with an adult (secondary intersubjectivity) and social referencing. Fairly sharply around 18 months some drastic changes occur in children's understanding of goals and desires. Children observing a failed action, e.g., trying to pull one of the balls off a small dumbbell, then imitate the intended successful action, not the actually observed action. They must have inferred the intended goal.

Leslie explains that the first Theory of Mind mechanism system –an Intentionality Detector- comes into play later in the first year and distinguishes goal-directed actions. It allows the infant to construe people and other agents as perceiving the environment and as pursuing goals. In Baron-Cohen’s model, the "Shared Attention Mechanism" serves to direct the infant’s attention to the object of the agent’s intentions and provides the means by which the child can develop representations of the agent’s mental contents. It makes information from the intentionality detector available to the eye-direction detector, and takes dyadic representations from the eye-direction detector as input to build triadic representations.

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.

Leslie explains this with a final Theory of Mind mechanism, which begins to develop during the second year of life, which distinguishes propositional attitudes. This third mechanism allows children to represent agents as holding attitudes toward the truth of propositions. Equipped with this mechanism, children are able to compute propositional attitudes such as Jane is pretending that this empty cup is filled with tea, Peter thinks that this candy box contains candy. Children do not have a problem with representation, as shown by pretend play…a type of propositional attitude.

Leslie's decoupling explanation argues that pretence and mentalising abilities require the functioning of the same innate module. The maturation of Theory of Mind mechanism system 2 distinguishes propositional attitudes and mediates the ability to understand pretence and the ability to understand false-belief and other mental states. Pretend-play skills develop during early childhood. This modular theory-of-mind mechanism permits the 18-24 month old to engage in pretend play and to understand as pretence the pretend actions of others. This metarepresentational capacity prevents the child from being confused when someone pretends that a banana is a telephone. It does so by decoupling the temporary pretend identity of the banana (telephone) from its permanent real identity (banana). The child can then compute the relation: "This person is pretending that this banana is a telephone." Evidence for this includes the fact that social flexibility in pretend play correlates with theory-of-mind task performance.

Autistics have beliefs and desires but can’t understand anothers’ beliefs are different from their own. They fail to decouple a representation from its seemingly fixed characteristics. The root of autist’s problem may be an inability to use meta-representations. If this were true, it would explain autists’ difficulty with pretend play.

If understanding of pretence and understanding of false belief are both mediated by Leslie's theory of mind mechanisms, then why does the former appear so much earlier in childhood than the latter? Why is there a roughly two-year age gap between children's comprehension of pretence and their comprehension of false-belief, deception, appearance v/s reality, and different perceptual perspectives? Leslie claims we’re born with a theory of mind module, and coupled with it is a selection processor. When there are tasks with two response options you’ve got to select the right one. As adults we suppress where the object actually is in the Maxi-task and say where Maxi thinks it is. Children can’t ignore what’s staring them in the face. But if the photo task (children have problems with non-mental representations too. Children see a Polaroid being taken of big bird on a bed. While it’s developing big bird moves to a chair. 3 year olds say big bird will be in the chair in the photo) and the false belief task both share the selection processor, shouldn’t they correlate more? In fact it’s quite common for a child to fail either of the tasks and pass the other.

There is evidence that young children’s understanding of pretence is not a propositional attitude. 2-year-olds and even older children lack a fully mentalistic conception of pretence as well as belief. Children were presented with a doll named Moe who knows nothing at all about rabbits but happens to be hopping like one. The children were then asked if Moe was or was not pretending to be a rabbit. Before the age of 4 or 5 years they say that Moe is pretending to be a rabbit, despite having agreed that she did not know how rabbits hop. Young children conceive of pretence in a non-representational way, as “acting like”. Having said that, if a character that had a boot on his fishing line was pretending that he had caught a fish, the children agreed (pointed to the relevant think bubble) that he was thinking of a fish rather than thinking of a boot. So the Moe finding may not be due to children’s problems with pretence so much as with their understanding of mental states. 3-4 year olds classify pretence with physical activities, such as clapping one's hands, rather than with mental activities, such as thinking. By the age of 7 or 8 most children respond like adult subjects to such tasks, insisting that someone who has a mental state about something (e.g. pretending to be or wanting a kangaroo) has to know what it (kangaroo) is.

A big problem with this account is, the story is consistent with the findings, but isn’t it just redescribing the findings?

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