Re: Cognitive architecture

From: Harnad, Stevan (
Date: Fri Feb 21 1997 - 17:43:13 GMT

> From: Josephine Seale <>
> in basic terms,computations such as decision-making are cognitively
> penetrable (i.e they can be affected by expectations, beliefs etc.) and
> that reflexes are cognitively inpenetrable (i.e they cannot be affected
> by beliefs etc.) The question I have is in relation to the role of
> perceptual processes. The book claimed that these processes are both
> computations and reflexes, but that they are, according to Fodor,
> cognitively inpenetrable. This was shown with relation to the idea that
> if you are sitting on a train and see the train adjacent to you moving,
> despite sitting still and knowing that you are not going to move for
> quite a while, you still get the illusion and feeling of moving.
> However, as shown by 'Devil's advocate box' (page 60) various
> situations in which perceptual processes are used can be cognitively
> penetrable, as the individual adapts to the situation. This idea can
> also be seen in reference to the illusion of the train above as, having
> been on a train a lot, I no longer get that illusion of feeling that I
> am moving. Ths, could it be that with practise or a high amount of
> exposure to a particular situation that a person's perceptual processes
> can, eventally, be affected by one's experiences. With this view in
> mind couldit therefore be possible that the majority of perceptual
> processes are, basically, cognitively penetrable ?

Perception can change with experience: If you look at a red spot for a
while, and then look at a white page, you see the green afterimage. But
this is not COGNITIVE penetration, it is a physiological adaptation
effect. Same is true with the apparent motion effects and after-effects
on a train. They may adapt out from repeated exposure, but they are not
altered by your knowledge or your beliefs. If they were, then all you
would have to say with the green afterimage is "I know this paper is
white, so I will see it as white." But that doesn't work. Same with the
train: KNOWING it is or is not moving doesn't alter the experience. Only
exposure and adaptation alter the experience, but that is not
cognitive penetration.

In contrast, when you first hear the Monty Hall problem, you are
sure that the right strategy can't be to switch. As you think about
it more (and get a few kid-sib explanations), you start to realise that
the right strategy is to switch after all.

Here's an important distinction, though: If it is by reasoning and
reflection that you come to realise that switching is the right
strategy, that's cognitive penetrability. But if you come to realise it
only by playing the game over and over (as I said some teachers have
you do when they are trying to show which strategy works best), then
that second way of changing your view of the game is a bit more like
perceptual adaptation than the cognitive change that comes with
purely theoretical discussion and reflection about the problem.

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