Relation of the Trail Making Test to Mental Retardation

Abstract

This study investigated the relationship between IQ and performance on the Trail Making Test (TMT) and attempted to determine the discriminatory power of the test at various IQ levels. There was a significant correlation between IQ and TMT performance, but this relationship was the result of very high correlations at the lower IQ levels and low or nonexistent correlations at the upper IQ levels investigated. The TMT did not differentiate between brain-damaged patients and functionally retarded patients at low level ranges (IQ < 70), but did discriminate between these groups at the higher IQ level investigated (IQ = 70–89). These findings were discussed in relation to earlier research indicating the influence of psychotic symptomatology on TMT performance, and it was concluded that the TMT may be a useful addition to a screening battery for identification of patients with organic brain pathology, providing that the patient is free of serious intellectual impairment and psychotic symptoms.