| Instrument | General description | Reliability data | Validity data |
| Booklet Category Test (DeFilippis, McCampbell, & Rogers, 1979) | Assess the ability to conceptualize qualities such as size, shape, number, position, and color. Consists of 7 sets of items, totally 208, and each is organized based on a different principle. Subjects must use feedback they receive from the correct and incorrect guesses in each series to infer the underlying principle. Requires the deduction of principles based on response-contingent feedback and then be able to abandon it when it is no longer effective. | High internal reliability coefficients for the total score of >.95 | While the Category Test is sensitive to variety of brain disturbances |
| Wisconsin Card Sorting Test (WCST; | Assesses abstraction ability and the ability to shift cognitive strategies in response to changing environmental contingencies. It requires strategic planning, organization and the ability to use feedback to shift cognitive set. Goal-orienting behavior and the ability to modulate impulsive responding are also measured. The test consists of presenting 4 stimulus cards to the subject. The subject receives 128 response cards that vary in color, form and number. The subject is told to match the response cards to the stimulus cards and given feedback each time on the correctness of the response. No warning is given that the sorting rule changed. Indices include preservative responses, failure to maintain set, and number of categories achieved. | Test-retest reliability difficult to measure in normal individuals. On retesting, it is no longer measuring problem solving abilities in the same manner as the subject are now aware of the category sorts and shifting principle | Convergent validity as a measure of executive function was demonstrated by regression analysis, with perseverative errors on the WCST loading on to a factor defined by the measure of Piagetian formal operations |