(Wechsler, 1944, p.4)
Intelligence is considered to be global as it characterises the individual's behaviour as a whole; it is a combination of those elements or abilities, which, though not entirely independent, are qualitatively differentiable. "By measurement of these abilities, we ultimately evaluate intelligence. But intelligence is not identical with the mere sum of these abilities, however inclusive". (Wechsler, 1944, p. 6) Wechsler suggests that there are three important reasons, which justify this statement:
(1) The ultimate products of intelligent behaviour are not only a function of the number of abilities or their quality but also of the way in which they are combined, that is, upon their configuration.
(3) Finally, while different orders of intelligent behaviour may require varying degrees of intellectual ability, an excess of any given ability may add relatively little to the effectiveness of the behaviour as a whole. It would seem that, so far as general intelligence is concerned, intellectual ability as such merely enters as a necessary minimum.
"Thus, to act intelligently, one must be able to recall numerous items i.e., have a retentive memory. But beyond a certain point and age in developmental life span, this ability does not help much in coping with life situations successfully". (Wechsler, 1944, p. ...