Use of Bayley Scales in Individuals with Profound Mental Retardation: Comparison of the First and Second Editions

Assessment of individuals with profound mental retardation is complicated by the limited number of instruments available. Our experience has been to use the Bayley Scales of Infant Development to obtain an estimate of developmental level. When comparing the first and second editions, we have found a decline in functioning for residents in instances where there has been no medical or neurological reason to account for such decline. Our results show that raw scores and age equivalents are lower with administration of the second edition of the scale. Clinicians should report a range of scores and functioning, rather than following a strict basal and ceiling rule for administration.