George Miller [Magical Number 7 +/-2] Part 1

Date: Fri Feb 27 1998 - 14:51:59 GMT


Part one of Miller article:


In the introduction, Miller's first reference is to "this number" which
he states can come in many different disguises in the way it can be
either bigger or smaller depending on the individual, but not to the
extreme that it becomes "unrecognizable". I presume that he is
referring to this "magical number + or - two that everyone seems to
rant and rave about... and so they should coz' I believe it has an
important significance and useful implications to the phenomena of
memory and how we recall information ( a cognitive process that I
believe is vital to everyday life... but I bet somewhere that there's a
bloke who cannot recall particular events or specific types of
information but still leads an ok life!)

Anyway... the way he tested this number was through the use of
"absolute judgement experiments" where they test how well participants
can "assign numbers to the magnitudes of various aspects of a
stimulus". In real English, they are testing the extent of people's
abilities to transmit information. It is also evident that the use of
the information theory has been widely applied to his own proposals.

Now that I've established the basics of this article, I'll get onto the
nitty-gritty stuff by attempting to review my part of Miller in basic
everyday comprehension!!

The issue of information measurement is commonly understood in the
light of "VARIANCE" which simply refers to the "amount of information".
The main principle here is that if you increase the variance, then you
will cause an increase in the amount of information too. Psychologists
like this way of talking as they believe it is easier to measure. And
at the end of the day, everyone likes to have an easy life! Actually,
it's understanding really coz' if you think about it, they are dealing
with a complex system of the human mind. He also says that a large
variance causes ignorance in people in our beliefs about what is going
to happen. To make this point easier to understand, I'll include an
example that Miller uses in the article;

> "If the variance is very small, we know in advance how our observation
> must come out, so we get little information from making the
> observation".

This concept is then discussed with reference to a communication
system, which obviously involves both an input and an output. Everyone
knows this already, but the hard bit comes when you think about the
variance between the two stages, how it determines the whole
communication process, and also what actually happens between these two
stages. The in between bit he calls the "covariance of the input and
the output". Or in other words he calls the covariance the "amount of
transmitted information".

Information measurement becomes more apparent when they perform these
absolute judgement experiments, where the aim is to gradually enhance
the amount of input information and then measure the amount of
transmitted information. The transmitted info is the part that they are
interested in as it shows the capacity of the subject's recall
abilities. The theory is that if the participant's absolute judgements
are fairly accurate, then the majority of the information will be
transmitted, thus retrievable from the person's responses. The way
they actually measure the level of absolute judgement is by observing
the amount of mistakes they make during the tasts.

The results generally show that at first, their recall abilities are
quite good and will gradually increase, buy after a while, the recall
capacity will "level off" so to speak, and it is this leveled bit that
they believe to be "the greatest amount of information that he can give
us about the stimulus on the basis of an absolute judgement". So, is
this whre he got this magical number from then? A final point to add is
that the fun and games of these experiments involve giving the
participant an increasing amount of alternative stimuli to observe,
instead of just increasing the amount of stimuli they produce.

This point is known as the "channel capacity" and is the point at which
confusion occur......

End of intellectual comment!

The last thing I wanna say is that at first, I found this bit of the
article confusing, but now that I have re-gurgitated it in my own
words, I actually think that I know what a cognitive psychologist is
going on about for a change!!!!

See you lot on Monday!


P.S. That was not a sarcastic comment by the way, before I get chucked out of

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