Implicit memory in aging adults with mental retardation with and without Down syndrome

Effects of age and IQ on implicit memory in adults with mild or moderate mental retardation with and without Down syndrome were examined. When the etiologically defined groups were equated on age (and IQ), an age-associated difference in implicit memory performance was not evident. When data were reanalyzed, including only participants with unspecified mental retardation from a broader age range, we found a significant but small age-related difference and a significant but small IQ-related effect on implicit memory. In summary, although implicit memory showed an age-associated difference and IQ-associated variation in adults with mental retardation, these effects were relatively small. Data support existing theories proposing the relative invariance of implicit processes across a range of individual differences in age and intelligence.