186 Discussion 



Dr. Lorge, you emphasized the difficulty in finding a yardstick for 

 intellectual capacity in older ages since you don't have schooling as the 

 criterion. You implied that such things as social intelligence must be 

 taken into account, also the intelligence shown in one's job or in one's 

 use of leisure. This is the sort of problem that has arisen in several other 

 contexts and that has been dealt with effectively by starting with cri- 

 terion groups made up of people who show to an extreme degree the 

 qualities which you are interested in, and then you use factorial analysis 

 or similar statistical procedure, for determining what tests will serve 

 your purpose best and yield a measure of the dimension or dimensions in 

 question. Here we are dealing with several factors which contribute to 

 the general notion of intelligence and we need statistical devices to 

 overcome at various ages the difficulty of not having a satisfactory single 

 criterion. 



Lorge: I have done factorial analysis on cross-sectional samples, using 

 Balinsky's data on the Wechsler. The percentage contribution of the 

 first principal component changes with age. In the age-9 group, the first 

 factor accounts for about 44 per cent of the total variance ; in the 12-year 

 group, 41 per cent; in the 15-year group, 31 per cent; in the 25- to 29-year 

 group, 27 per cent; in the 35- to 44-year group, 38 per cent; and in the 

 50- to 59-year group, 50 per cent. This is the complication that is intro- 

 duced, so that while your suggestion, Prof. Lewis, is meritorious, what we 

 have here is that the principal component is based on a very limited 

 array of tests, and what we would have needed is of the order of 40, 

 rather than of 10, different kinds of tests. Jones and Conrad assert that 

 a youngster gets 25 per cent of his score from both the vocabulary and 

 information test, but an adult gets approximately 40 per cent of his 

 total performance from those two tests. It is the same thing, the 

 principal component is variable and it seems to be smallest around 30 

 years, which is the age at which reaction time begins to affect perform- 

 ance. 



The other issue is whether we have a cultural phenomenon related to 

 the concepts of accuracy: the data on older people seem to indicate that 

 accuracy is something that these people work for and work at. They like 

 to be accurate, they are not always so. In our work with the Western 

 Electric Company in the United States during the war, they re-hired — 

 at my suggestion— a number of people who had been retired. The total 

 performance over the year in terms of useable products was greater for 

 the re-hired people than for the regular younger staff. The reason was 

 that the youngsters did not mind taking a day off to go fishing, whereas 

 none of the oldsters did that. The only occasion on which they would take 

 time off was when they were really ill. It seems as if the older people 

 have devotion to task, commitment to accuracy and maintenance of 

 material. Now is that cultural? Will our next generation be less that 

 way ? I cannot say, but it is an important phenomenon. We have to be 

 aware of it; 50 years hence we may have a different kind of behaviour. 



Welford: My comment to Prof. Lewis is that I think the possible 

 inequalities of motivation in subjects of different ages are of a kind such 

 that one has to limit the inference that one makes from any experimental 



