Aside from being an age-old philosophical problem, the question of our knowledge of the outside world is one that has interested developmental psychologists since Jean Piaget (1896 – 1980, one of the fathers of developmental psychology). Piaget thought that at birth infants are profoundly egocentric, not realising that anything exists beyond their own experiences and actions. It takes some time for them to understand that there exists an independent realm of objects – things that are "permanent, substantial, external to the self and in firm existence even though they do not directly affect perception".
So how do psychologists decide when a child has knowledge of the outside world?
The classic experimental paradigm for studying “object permanence” involves a search task. In this task the child has to search for an interesting object, such as a toy car, that he has watched being hidden. At the age of about seven months, children begin to start 'passing' this task, picking up the cup to reveal the toy car.
But this seems quite late. Don't children realise that the external world exists before this age?
Results gained by using a different experimental paradigm seem to suggest that object permanence develops far earlier. This second technique uses a similar task, but rather than having the child physically search for the object, they simply watch a scene unfolding in front of them whilst their reactions are observed. If they are surprised (which is judged by how long they look for) when the cup is lifted up and the toy car is not there (it has been removed through a trap door), it is inferred that they expected the car to be there and thus knew that it continued to exist when it disappeared from their sight.
But these results seem to create a paradox – the “paradox of object permanence”. Why do infants who have the motor capacity to search for objects, and who seem to know that objects continue to exist when they are hidden, fail to search for objects until they are seven months old?
One attempt to resolve this paradox claims that the infants in question do not know, in the relevant sense of the word, about the permanence of objects. The idea here is that their “surprise” at physically impossible events happening (such as a cup being lifted up and the toy car not being there) can be accounted for by their possessing some sort of perceptual residue, or after-image, of the toy car, rather than a full-blown representation of it.
An alternative attempt to resolve the paradox claims that whilst the infants do know that the toy car continues to exist, they do not actually have the necessary motor capacity to be able to search for it. Certainly, infants of 4-7 months can grab and pull and lift things, but they struggle to put sequences of these actions together in order to fulfil their goals. For example, infants of this age will not pull a blanket towards them in order to retrieve a visible toy at the other end of the rug. Furthermore, they will search for “invisible” objects in the dark when such searching does not involve complicated sequences of actions.
So?
It seems that by four months of age infants possess some idea that objects continue to exist when they cannot be seen. But are they correct in thinking this??? That's a question for the philosophers.
Well, the common sense view is that of course objects exist when we don't see them. The universe is 15 billion years old mankind about 30,000 years. Did the universe only come into existence 30,000 years ago when homo sapiens was around to see it. I think not.
ReplyDeleteBut did it even exist before you were born??? Wittgenstein says that this sort of background belief is, in a way, something that we assume without compelling evidence; it forms part of our 'background' for getting along in the world. We couldn't get by without assuming that the world existed before our birth, but when it comes down to it we wouldn't even know how to test this assumption.
ReplyDeleteInterestingly, some theorists argue that in schizophrenia this 'background' of core assumptions is disrupted, such that some rational belief structures lose their underpinnings..
Of course the universe existed before we were born.There are fossils 500 million years old, there is 13 billion year old light from distant galaxies. Why is this not'compelling evidence' ? It's sophistry to argue that before we existed there was nothing: our ancestors must have existed otherwise we wouldn't be here. When did the great chain of being start though? Wittgenstein talked a load of old twaddle which wouldn't have had an airing outside Cambridge.
ReplyDelete