Each item on the Cognitive subtest has explicit administra- tion and scoring criteria that are best practiced and learned before testing a child. The manual suggests examiners should become sufficiently familiar with the administration directions so as to not need to read from the manual during the assess- ment. Although the Bayley-III subtests may be administered in any order, examiners may choose to administer the Cognitive subtest first because the tasks are engaging and do not require a verbal response. Test entry point is determined based upon the child’s age and this helps ensure the child’s initial success.
In the case of infants born before the 37th week of gestation, the manual allows for age adjustment through 24 months of chronological age. The intention of age adjustment, also known as ‘‘corrected age’’ in the medical literature, is to take prematurity into account in assessing neurocognitive development, growth, and medical outcomes in preterm children (American Academy of Pediatrics (AAP), 2009). In order to make the adjustment, the prematurity is calculated in weeks and months, and is then subtracted from the chronological age. The resulting number of months and days are then recorded in the row labeled ‘‘Adjusted Age.’’ Several calculators for determining age adjustments may be found online (March of Dimes, 2009), or may be downloaded as i-Phone applications. Best practices would include deriving summary scores for both adjusted and chronological ages.
The basal level is determined by obtaining a score of 1 on three consecutive items. Testing should continue until the ceiling is reached – namely, five consecutive scores of zero. Qualitative information (e.g., on the child’s language and test behavior) ought to be recorded on the record form, as this information may help later when scoring and interpreting results.
Items that comprise a series are conveniently identified as such, and may be administered and scored at the same time. For example, theBlue Board Seriesbegins with Item 51 (1 piece in 150 seconds), continues to Item 58 (4 pieces in 150 seconds) and finally to Item 66 (9 pieces in 75 seconds). Otherwise, items should be administered in order, as they are grouped by diffi- culty. Rules for scoring multiple responses are specified in the
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manual. As a rule of thumb, the best response is credited, but one should always consult with the manual. Timed items are cued by a clock symbol on the protocol, with the number of seconds specified – information that is helpful to the examiner.
Seating and positioning is not specified in the manual for the Cognitive subtest. We have found that supported sitting at a table across from one another works best for very young babies or for those children needing more stability. Toddlers may enjoy sitting on the floor with the examiner and parent, while older children may be most attentive when seated at a sturdy table and on a chair of a comfortable height. If evalu- ated in a playroom, the examiner should consider limiting distractions by removing other toys in order to engage the child in the testing. The examiner should be aware of signs of fatigue, and allow for breaks as needed.
As with the Bayley-III subtests, the total number of passes together with the number of unadministered items below the basal level are summed, resulting in a raw score. This raw score then is converted to a scaled score, using Table A.1 in the manual.
The scaled score has a mean of 10 and a standard deviation of 3.
A composite score that combines the cognitive and the social- emotional subtests is determined by using Table A.5. This composite score has a mean of 100 and standard deviation of 15.
All scores are recorded on the front page of the Bayley-III Record Form. The profile may be charted on page 2 of the Record Form. We have found the recording and profiling of scores to provide a useful visual aid when interpreting scores to care- givers. Discrepancies between scores also may be determined through using Table B.2 and then documenting them on page 2.
Growth scores are a novel concept included in the Bayley-III, and may be used to document growth towards outcomes.
Similar to height and weight charts used by pediatricians to document growth velocity, and educational assessment tools used for progress monitoring, Bayley-III cognitive growth scores provide an opportunity to chart and observe cognitive growth over time (Centers for Disease Control and Prevention (CDC), 2000;Ostrosky & Horn, 2002). Table B.6 is used to plot Bayley-III growth scores; this converts the raw score to the growth score equivalent. Then, the scores are plotted on a copy of the growth chart in Appendix H. There are growth charts available for ages
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1–18 months, 18–36 months, and 24–42 months. Figure 2.1 provides an example of the Bayley-III Growth Chart utilized in the case study described below.
Finally, while developmental age equivalents may be obtained and are perhaps more understandable for caregivers
FIGURE 2.1 Case study: Cognitive Growth Chart for Katie Doe.
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than standard scores, caution should be used in their applica- tion and interpretation. Developmental age scores are based upon the average age in months in which a given total raw score is obtained – for example, if the average raw score of 2-year-old children is 62, any child obtaining a score of 62 receives an age equivalent of 2 years. Thus, one cannot compare the child’s performance to the peer group. Furthermore, the distribution of age scores does not represent equal units, and small raw-score changes may result in large changes in resulting developmental age equivalents. Percentile scores may offer a more straight- forward explanation to parents of their child’s position relative to the standardization sample; for example, a child who scores at the 50th percentile has performed better than 50 percent of similar age children in the norm sample (Sattler, 2008). We find age scores most useful in describing performance within the context of development for severely delayed children, who may exceed the age range for the Bayley-III.