Development and initial validation of a new procedure for evaluating adequacy of effort given during neuropsychological testing: The letter memory test.

The authors report on results from a new procedure for evaluating adequacy of effort given during neuropsychological testing. The letter memory test (LMT) is a computer-administered, 45-item, forced-choice recognition task that uses consonant letters as stimuli and manipulates face difficulty level along 2 dimensions: number of letters to be remembered and number of choices amongst which the target stimulus must be identified. In 3 studies that included either analogue or known groups designs, the LMT discriminated poorly motivated from well-motivated groups at a moderately high level of accuracy, which was comparable to that of the Digit Memory Test and superior to that of the 21-Item Test. The internal consistency reliability of the LMT was also high.