Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

324 Educability and Group Differences
variable, the less likely we ought to expect relationship to school
success. . . . As it is, there is good reason to think that school
achievement is a result of a host of variables in addition to cognitive
variables’ (p. 51). It seems likely, however, that Bosco
underestimates the relevance of his measure of scholastic performance.
This could be tested by determining correlations at
the first grade, and by increasing the information load of the task
at sixth grade in order to yield sufficient variance to permit
significant correlations to show up.
REACTION TIME
Reaction time (RT) to a stimulus situation increases as the amount
of information transmitted by the stimulus increases. RT increases
as a linear function of ‘bits’ of information, and thus the rate of
increase in RT can be taken as a measure of information processing
capacity. (It has been reported also that the slope of this function
is negatively correlated with IQ [Roth, 1964, cited in Eysenck,
1967].) A description of one experimental procedure for demonstrating
this measure will help to make it clear. The subject sits
in front of a panel on which there is a single light bulb; directly
beneath the bulb is a pushbutton. When the light flashes ‘on’, the
subject pushes the button to turn the light ‘off’. In this condition,
the subject’s response time is a measure of simple RT. There is
zero information conveyed when there is only one light/button
combination. But the subject is required to respond to an increasing
number of light/button combinations, simply by having one
light go on among an increasing number of potential alternatives.
This is called ‘choice RT’. The amount of information conveyed
increases logarithmically as the number of lights increases.
Fox and Taylor (1967) compared two groups of army recruits
on simple RT and choice RT. One group (low AFQT) was selected
from recruits having scores between 10 and 21 on the Armed
Forces Qualification Test (a composite measure of general
intelligence and basic scholastic attainments); the other group
(high AFQT) were recruits with scores from 90 to 99. The groups
differed significantly in choice RT, but not in simple RT. (A
more detailed description of the apparatus, procedure and results
of this experiment is presented in Jensen, 1970b, pp. 149-51.)
Also, Oswald (1971) found a correlation (r = —0-41) between