Measuring Intelligence

Abstract

In Chapters 1 and 2, I made the point that the concept of intelligence, or specifically low intelligence, has been part of the construct of intellectual disability for centuries. Since the turn of the twentieth century the definition of intellectual disability has included having an IQ below a specified cut-off point. In the last chapter I looked at how the concept of intelligence and its measurement has developed over the years. In this chapter I want to examine in more detail how accurately intelligence, particularly low intelligence, can be measured with current tests.