Answer to Question 1
An integrative approach would combine models of various kinds of cognitive functioning as bases for intelligence. In such an approach, four sources of individual differences in intelligence might be detected. These are (1) breadth of declarative knowledge, (2) breadth of procedural skills, (3) capacity of working memory, and (4) speed of processing. The advantage of this approach is that it does not try to localize individual differences in intelligence as coming from one source. Rather, multiple sources are involved.
Answer to Question 2
Working memory is a critical component of intelligence. Indeed, some investigators have argued that intelligence may be little more than working memory. In one study, participants read sets of passages and, after they had read the passages, tried to remember the last word of each passage. Recall was highly correlated with verbal ability. In another study, participants performed a variety of working memory tasks. In one task, for example, the participants saw a set of simple arithmetic problems, each of which was followed by a word or a digit. An example would be Is (3 5) 6 = 7? TABLE.. The participants were given sets of two to six such problems and solved each one. After solving the problems in the set, they tried to recall the words that followed the problems. The number of words recalled was highly correlated with measured intelligence. Working memory measurements may closely predict scores on tests of general ability. Other researchers have demonstrated a significant but smaller relationship between working memory and general intelligence. Thus, it appears that the ability to store and manipulate information in working memory may be an important aspect of intelligence. This is probably not all there is to intelligence, however.