Human Judgment and Estimation of Premorbid Intellectual Function

David A. Kareken, J. Michael Williams

Research output: Contribution to journalArticle

20 Scopus citations


The following experiments examined clinical judgment in estimating premorbid intellectual function (IQ). In two experiments, clinical neuropsychologists were asked to (a) specify their beliefs about the interrelationships between IQ and demographic predictors, and (b) estimate IQ scores for hypothetical individuals. The clinicians believed that the relationships between the variables were stronger than previous research has established. On the judgment tasks, the clinicians provided narrower confidence intervals than those derived from their beliefs about the correlations, although this effect was primarily limited to estimates of Performance IQ. There were also discrepancies between clinicans' beliefs about the IQ-predictor correlations and the correlations between the clinicans' IQ estimates and the same predictors, suggesting inability to appropriately regress estimates. Although the clinicians' IQ estimates were close to those of an actuarial formula using the same information, their confidence was considerably higher. Constraints on human reasoning and memory disable clinical reasoners from making estimates of premorbid IQ that reflect the predictive power of demographic variables.

Original languageEnglish (US)
Pages (from-to)83-91
Number of pages9
JournalPsychological Assessment
Issue number2
StatePublished - Jun 1994
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Psychology
  • Psychiatry and Mental health

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