Re: The Bell Curve : Reaction time and IQ

Rod Hagen (
Tue, 04 Apr 1995 10:33:20 +1000

In article <>, (Arun
Gupta) wrote:

> People may remember the claim that reaction time experiments (which
> have no built-in bias, by their very nature) show that there is a
> significant black/white difference. Furthermore, it is claimed that
> these tests correlate significantly with IQ. [see for example page
> 282-283 of Murray and Herrnstein's TBC ].

I see no reason to accept that reaction time is actually free of bias.
Anybody who has played a computer game with a reaction time component
knows that there is a substantial amount of improvement with practice, and
that this improvement continues for a substantial period of time after
first exposure to the task (perhaps even weeks or months).

The simple fact that a primarily "sensori-motor" task is involved doesn't
remove the importance of "learning", and therefore depends, at least in
part, on socio-environmental factors. I would have thought that diet,
motivation, health (both past and present) and other environmental factors
would also be likely to play a significant part in performance.

Its interesting the way that the testers like to find measuring devices
that mirror technical process, and then assume they are looking at
something "pure". If they want to see the fallacy of their assumptions,
all they need to do is line up a group of "experienced" (i.e previously
used for various tasks) computers of the same brand and run some reaction
time tests on them. They will find that the performance of the computers
varies according to their previous "life histories". Fragmented hard disks
etc will prduce a substantial difference in their operating speeds.

If they want to take this very simple model a little further, have the
same computers running a variety of other software while undertaking the
"reaction time" tests (to approximate the intervening variables that go on
in peoples minds, like worrying about the mortgage or the rent , or their
kid in gaol, or how they are going to scrape together enough food for
dinner tonight). Try varying the line voltage a little too (to emulate
ill-health). They will find the results illuminating.

I have very little time for the current trend towards "information
processing" models of intelligence which come close to equating human
differences to those of the "Intel" versus "PPC" variety. They fall down
for a host of reasons beyond those expressed here. But even within the
confines of the electro-mechanical world, a little bit of "environment"
can make a huge difference in test results!

Rod Hagen