Bayley III: A Preliminary Overview (2007)

The Bayley Scales of Infant and Toddler Development--Third Edition (Bayley-III; Bayley, 2006) is the latest revision of the Bayley scales (Bayley, 1969, 1993), a widely utilized standardized instrument designed to individually assess the developmental functioning of infants and young children between the ages of 1 month and 42 months. This Bayley revision was conducted to improve the overall quality and utility of the instrument (Bayley, 2006). Specifically, the Bayley-III revision attempts to significantly address previous criticisms of the instrument, including: complicated administration procedures, administration and scoring concerns, inadequate floor and ceiling, limited information for intervention, and limited clinical utility (Alfonso, Russo, Fortugno & Rader, 2005; Gauthier, Bauer, Messinger, & Closius, 1999; Lichtenberger, 2005; Mayes, 1997; Ross & Lawson, 1997). In response to the established literature regarding the poor predictability of cognitive ability assessed in infancy and early childhood on later IQ and academic functioning (Black & Matula, 2000; Lichtenberger, 2005), this revision seems to emphasize more clearly than in previous manuals that the Bayley-III is not an intelligence test, nor should it be used to predict later academic achievement. It is also emphasized that the Bayley-III is not meant to be used as a measure of deficits in a specific skill area, and that referrals for further evaluation with other more narrow-band assessment measures be made for that purpose. Instead, the developers describe the Bayley-III's primary purpose as one of identifying children with developmental delays and providing information for intervention planning (Bayley, 2006). In the development of the Bayley-III, several specific revision goals were identified: 1) to update the normative data; 2) to develop five distinct scales; 3) to strengthen the psychometric quality of the instrument; 4) to improve the clinical utility of the instrument; 5) to simplify administration procedures; 6) to update administration; 7) to update the stimulus materials; and 8) to maintain the basic qualities of the Bayley Scales (Bayley, 2006, p. 11). The purpose of this review is to offer a brief description and preliminary critique of the aforementioned revisions, specifically discussing areas of obvious improvement, delineating areas of potential continued difficulty, and articulating possibilities for future consideration and research. Development of Five Distinct Scales One major change that evaluators will note immediately upon perusal of the instrument is the development of five distinct scales. Whereas the Bayley Scales of Infant Development-II (BSID-II) yield three scores (a Mental Development Index (MDI), a Psychomotor Development Index (PDI), and a Behavior Rating Scale (BRS) Total Score), the Bayley-III yeilds scores for five developmental domains: Cognitive, Language, Physical, Social/Emotional and Adaptive. The five scales included were chosen to correspond to the Individuals with Disabilities Education Improvement Act (IDEA) guidelines (1990, 1997, 2004) for assessment of early childhood. Of the five scales, three (i.e., Cognitive, Language and Motor) are administered individually by the examiner to the child. The language-dependent MDI had been a major source of difficulty and criticism of the BSID-II when used to assess children whose language development is delayed (Lichtenberger, 2005). Often the MDIs of these children were underestimated due to the high language demands of the scale. An attempt has been made to differentiate between the assessment of cognitive and language skills, with a reduction in the language load in the Cognitive Scale, allowing for naturalistic directional cues such as gestures, permitting examiners to accept responses that 'show evidence' of the target response... and provid[ing] graded levels of support during the administration of an item (Bayley, 2006, Administration Manual, p. …