Low-level lead exposure and contingency-based responding in preschoolers: an exploratory study.

Two reversal paradigm tasks (spatial reversal and spatial reversal with irrelevant color cues) originally designed to assess contingency-based responding in primates were adapted for use with 139 preschool children with a mean peak blood lead level (BLL) of 4.2 microg/dl (SD = 2.2). Sixty-nine children with BLL > or =5 microg/dl and 70 children with BLL of <5 microg/dl were included. Results indicated that preschool children with low-level lead exposure take longer to learn associations than preschool children with very low levels of lead exposure, and this difference cannot be attributed to increased distractibility or perseverative responding. These results support the use of these measures to assess specific cognitive functions in preschool children.