Classic experiment by Held and Hein

The well-known experiment on vision performed by Held and Hein: They harnessed a pair of kittens to a carousel (see the figure). One of the kittens was harnessed but stood on the ground and was able to rotate around by itself, while the other, being placed in the gondola, was only moved passively. As the one kitten walked, both moved in the circle.

[Held, R. and Hein A. (1963). Movement-produced stimulation in the development of visually guided behavior. Jouranal of Comparative and Physiological Psychology
56(5): 872-876.]

None of them have received light before the experiment, as they both were reared in darkness from birth. The point of this experiment is that both kittens were made to learn to see the world, receiving the same visual stimulation. The difference was that the one could move actively, the other was moved passively.

According to Held and Hein, only the self-moving kitten developed the normal visual perception. The other one, which was deprived of self-actuated movement, could not develop the depth perception. For example, it doesn't blink to an approaching object. In its visual field, I think, something looks 'bigger' when approaching, but never looks 'nearer'. The change of patterns in the visual field does not have the spatial meaning for the kitten.

The self-actuated movement is necessary in order to develop the normal visual perception with depth. Our movement in the world, the movement from here to there or there to here, gives the dimension of depth to mere visual sensations. Movement is the key to understanding the vision.

The primary function of mirror neurons

Mirror neurons were first discovered in monkeys but the relevant brain activity has also been found in the premotor cortex, the somatosensory cortex and the other areas in humans. As is well known, mirror neurons are active when one performs a specific movement, and when one observes someone else doing the same motion. Neurons in our brain “mirror” the action of the other, as if the observer himself were acting in the same way.

Giacomo Rizzolatti, one of the discoverers of the mirror neuron, says that the mirror neurons "are primarily involved in the understanding of the meaning of 'motor events', i.e. of the actions performed by others". That is, the monkey "sees the experimenter shaping his hand into a precision grip and moving it towards the food, it immediately perceives the meaning of these 'motor events' and interprets them in terms of an intentional act".
[Rizzolatti, G. and Sinigaglia, C. (2008) Mirrors in the Brain. Oxford University Press. p.97-98]

Thus, the primary function of mirror neurons is to perceive another person’s movement as an intentional action. In other words, the other person’s movement provokes the same potential movement, the same potential action, the same intention in us, through mirror neurons. In the fundamental level, we do not need to infer the other’s intention from the objective point of view, nor to project our own intention to another from the subjective point of view. (Here is the point to remember the theory of mind debate).

The other’s movement appears to us as a meaningful action, from the very beginning.

Simulation Theory vs Theory Theory

Another simulation theorist Alvin Goldman supports the ideas proposed by Gordon. Goldman summarizes more clearly what the simulation theory is.

[W]e do not use mathematical decision theory (i.e. expected utility theory) to make predictions; rather, we consider what we should do if we had the relevant beliefs and desires....they [*we] ascribe mental states to others by pretending or imagining themselves to be in the other's shoes, constructing or generating the (further) state that they [*we} would be in, and ascribing that state to the other. In short, we simulate the situation of others, and interpret them accordingly.
[Goldman, A. I. (1989/1995). Interpretation Psychologized. in M. Davies and T. Stone (Eds.), Folk Psychology: The Theory of Mind Debate. Oxford: Blackwell. p.81]

According to the simulation theory, in order to understand the others, we first put ourselves in the situation of others. We imagine what we would feel, think, and do in that situation. And then, we attribute the simulation result to the others.

Now we can contrast the theory theory and the simulation theory. Theory theory is based on the observation of others from third person's perspective (as is seen in the false-belief test), and stresses the role of folk psychological theory to predict the behaviors of the others. Simulation theory is based on the subjective simulation of others from virtual first person's perspective, and stresses 'what I would do' in order to predict the behaviors of the others.

The point of disagreement between these two theories is clear.

Objective, third-person's view on the other vs. Subjective, first-person's view on the other

Which side do you take?

false-belief test

A talk on the theory of mind (ToM) continues.

Wimmer and Perner (1983) proposed the so-called 'false-belief test', which examines human children's ToM. (The need for testing the 'false-belief' was originally claimed by the philosopher Dan Dennet, as a comment on the 1978 paper by Premach and Woodruff. About their chimpanzee experiments, see the previous post on this blog). The test should have the following formal paradigm.

[T]he subject is aware that he/she and another person observe a certain state of affairs x. Then, in the absense of the other person the subject witnesses an unexpected change in the state of affairs from x to y. The subject now knows that y is the case and also knows the other person still believes that x is the case.
[Wimmer, H. & Perner, J. (1983) Beliefs about Beliefs: Representation and constraining function of wrong beliefs in young children's understanding of deception. Cognition, 13:103-128, p.106]

Based on this paradigm, Wimmer and Perner constructed the well-known 'chocolate task';

[A] story character, Maxi, puts chocolate into a cupboard x. In his absence his mother displaces the chocolate from x into cupboard y. Subjects have to indicate the box where Maxi will look for the chocolate when he returns. Only when they are able to represent Maxi's wrong belief ('Chocolate is in x') apart from what they themselves know to be the case ('Chocolate is in y') will they be able to point correctly to box x. This procedure tests whether subjects have an explicit and definite representation of the other's wrong belief.
[op.cit., p.106.]

The result is enough interesting (and also well-known) that none of the 3 to 4 years old children pointed 'correctly' to the cupboard x. 57% of 4 to 6 years old, and 86% of 6 to 9 years old children pointed 'correctly' to the cupboard x.

They conclude;

[i}t seems, therefore, that the emergence of children's ability to understand another person's beliefs and how this person will react on the basis of these beliefs...seems to emerge within the period of 4 to 6 years.
[op.cit., p.126.]

I agree with their conclusion. The theory of mind is formed in children after (or around) being 4 years. This fact is well examined in many other experiments.

But now, we come to one simple question. If the children under 4 years of age don't have the theory of mind, can't they understand the other person or predict her/his behavior at all? After being 4 years old, they suddenly start to understand the others? If the theory of mind is the only way to understand the others, none of us can understand the others before the birthday party of 4 years old. It sounds so funny, doesn't it?