J.—PSYCHOLOGY 163 
become sufficiently serious to handicap the individual in occupations 
where visual requirements are exacting. In industry, of course, there 
are other factors which affect the issue, such as the efforts of an employer 
to get cheaper, that is, younger, labour, or the effort of the employee him- 
self to acquire a more responsible position. The more striking fact, 
according to Miles, is the relatively small, although steady, decrement 
shown throughout the life-span in tests such as reaction speed or rotary 
motility. “Guessed on the basis of what industry has popularly said of 
the old and also in terms of the derogatory reports made by old people 
about themselves, the situation has appeared far harsher than the objective 
data warrant.’ 
INTELLECTUAL ABILITIES. 
Under this heading may be considered tests of memory, manipulations 
of symbols and of space areas, interpretations of meaning in verbal form 
and all the so-called higher mental functions which figure in tests of 
intelligence. Here again the deterioration due to age as such is relatively 
small. The differences between individuals at the older ages are often 
quite marked, so that other factors are probably at least as weighty as age 
in accounting for an individual’s actual score. ‘Thus Sorenson found that 
the mental abilities of adults who participate in schemes of adult education 
are maintained at a high level over a long span of adult years. 
Miles also points out that when speed is the stressed element in an 
intelligence test for adults, then the decrement due to age is greater than 
it is when power in unlimited time is stressed. ‘The fact that intelligence 
tests are usually standardised for children also points to the need of 
further research when dealing with adults. 
INTERESTS. 
Here we turn to one of the Stanford Later Maturity Publications— 
namely, Change of Interesis with Age, by Prof. Edward K. Strong. 
It is based on examination of more than two thousand men between the 
ages of twenty and sixty representing eight occupations. The following 
quotation gives the author’s standpoint: ‘If “ vocational interest’ is 
defined as “‘ the occupation an individual likes best now,” then the con- 
clusion must be reached that vocational interests are very unstable. 
There are ample data to prove that boys and girls and also older persons 
change their “‘ first choices” very frequently, and in most cases without 
apparent rhyme or reason. But if “‘ vocational interest’’ is defined as 
“the sum total of all interests that bear in any way upon an occupational 
career,” then we find surprising stability, certainly among adults, and, as 
far as we have been able to judge, also among young men of college age 
and presumably among still younger people.’ 
That is to say, just as we do not probe an individual’s intelligence by 
one test but by as many as we can afford time for, so it should be with 
interest. 
The slight differences found between men of twenty-five and fifty-five 
years of age seem to indicate that interests are not particularly affected 
