Question

in estimating the intelligence of a person weschler used

Answer 1

In estimating the intelligence of a person Weschler used the concept of performance and not capacity. His scales are not purported to measure one's quantity of intelligence, but instead, measures one's intellectual performance. The reason for conceptualizing intelligence as a performance variable is that it does not really matter how much intelligence one has, in order to adapt to the environment. What matters is how well one uses his/her intelligence. Since intellectual capacity cannot be seen nor its existence concretely verified, it cannot be reliably measured. Performance can be measured and, thus, should be the focus of the test. Most major intelligence tests are grounded in the view of intelligence tests as performance measure, on the concept explained by Weschler.