Maximum effort may not be required for valid intelligence test score interpretations

Intelligence tests are assumed to require maximal effort on the part of the examinee. However, the degree to which undergraduate first-year psychology volunteers, a commonly used source of participants in low-stakes research, may be motivated to complete a battery of intelligence tests has not yet been tested. Furthermore, the assumption implies that the association between test-taking motivation and intelligence test performance is linear – an assumption untested, to date. Consequently, we administered a battery of five intelligence subtests to a sample of 219 undergraduate volunteers within the first 30 min of a low-stakes research setting. We also administered a reading comprehension test near the end of the testing session (55 min). Self-reported test-taking motivation was measured on three occasions: at the beginning (as a trait), immediately after the battery of five intelligence tests (state 1), and immediately after the reading comprehension test (state 2). Six percent of the sample was considered potentially insufficiently motivated to complete the intelligence testing, and 13% insufficiently motivated to complete the later administered reading comprehension test. Furthermore, test-taking motivation correlated positively with general intelligence test performance (r ≈ 0.20). However, the effect was non-linear such that the positive association resided entirely between the low to moderate levels of test-taking motivation. While simultaneously acknowledging the exploratory nature of this investigation, it was concluded that a moderate level of test-taking effort may be all that is necessary to produce intelligence test scores that are valid. However, in low-stakes research settings, cognitive ability testing that exceeds 25 to 30 min may be inadvisable, as test-taking motivational levels decrease to a degree that may be concerning for a non-negligible portion of the sample.