The specificity of behaviors and measurements

This essay examines the fundamental fact of specificity in behaviors both outside and inside the testing room. Two tests of the same construct typically have a moderate to low correlation between them, the level of relationship depending on whether the mode, the situation, the task, and the stimuli for one test are similar to or different from those for the other. The great majority of psychological tests have considerable specificity. Their scores tend to correlate far less than perfectly with other tests of the same variable. Even when an ability is defined within a model such as Guilford's Structure-of-Intellect, each test of that ability will usually have some specific determinants not shared by other tests of that aspect of intelligence. Moreover, such a test is likely to correlate almost as well with tests of other similar abilities as with tests of its particular one.