Guilford rejects the idea of a general intelligence factor and also broad factor groups like Thurstone’s primary abilities. He believes that many aspects of intelligence tend to be ignored when items are lumped together to form tests. An item used as a test of verbal ability is distinguished from one that is nonverbal on the basis of its content-words as opposed to pictorial material.
But, what one does with the content of the test item (e.g., memorizes it or uses it to engage in a reasoning process) will depend upon the nature of the task and may be relatively independent of the content. Suppose that you are shown a picture of a dozen different objects and told that you will be asked to recall the names of the objects at some later time.
Does this task involve verbal or pictorial ability? To be sure, a picture is presented, but, most subjects will name the objects and then rehearse the names rather than try to memorize the picture itself.
Guilford maintains that intelligence test items should not be distinguished in terms of content alone, but, also in terms of the operations performed upon the content and the product those results. His structure-of-intellect model shows the way in which 4 contents, 5 operations, and 6 products combine to yield 120 unique intellectual factors. The definitions of each type of content, and operation are too lengthy to present here.
Each of the small cubes in the slid represents a unique intellectual ability. An intelligence test item can be distinguished in terms of its content, the kind of operation the subject must perform on the item, and the product resulting from the particular operation applied to a specific content. According to Guilford, there are 4 types of content, 5 possible operations, and 6 products-yielding 120 identifiable abilities.