Chapter 7
BAYLEY SCALES OF INFANT DEVELOPMENT
7.1 Introduction
The Bayley Scales of Infant Development III (BSID-III) will be administered at the 24 months +/- 2 months (adjusted age) visit. The BSID-III consists of three parts: the Mental Scale, the Motor Scale, and the Behavior Rating Scale, which the examiner completes after the assessment. Estimated time to administer the BSID-III for this age level is 1½ hours.
7.2 Reliability and certification
Examiners must have been previously certified in the use of the Bayley III and have demonstrated proficiency in this exam based on local standards. Examiners must also be familiar with administering the Modified Checklist of Autism in Toddlers (M-CHAT).
7.3 Procedural guidelines
The following is a list of procedural and scoring guidelines. The guidelines are consistent with the BSID-III manual unless noted.
7.3.1 Primary Caregiver
The primary caregiver should accompany the child during the administration of the BSID-III.
If the primary caregiver is not present, the adult who brought the child to the clinic should stay with the child.
7.3.2 Masking of Examiners
Examiners should be given the child’s corrected age prior to testing. They should not review a child's chart prior to the exam in order to stay masked to the neonatal history of the child, including gestational age and birth weight, and to clinically significant family and developmental history, including the results of previous developmental testing.
Observation made during the assessment that the child has had particular medical conditions or knowledge that the child had been referred at a previous clinic visit does not count as unmasking.
7.3.3 Non-English Speaking Children
It is preferable to perform the test in the child's preferred language. Non-English speaking families may require that the examiner arrange translation. If a translator is needed, inform the translator to translate instructions as closely as possible, not rewording or repeating instructions unless permitted by the examiner.
If more than 2 items are spoiled by the translator, the test cannot be scored. Exception: Some children may understand both languages and therefore hear the directions twice the specified number of times; by consensus of examiners, this will not constitute reason to spoil items.
7.3.4 Children with visual, hearing, and/or upper extremity impairments
Visual, hearing, and/or upper extremity impairments may be identified by various means, e.g., upon review of medical information by the research nurse; questioning of parents during scheduling procedures; neurological examiner’s observations, and/or Bayley examiner’s observations, and serve to alert the Bayley examiner to any severe impairments that are likely to affect the child’s BSID-III examination, e.g., severe hearing impairment, severe cerebral palsy.
When a child’s impairments prohibit standardized administration of the Bayley Mental Scale, the examiner will administer the BSID-III Motor Scale and use clinical judgment to decide whether completion of the Behavior Rating Scale is appropriate, i.e., whether or not all of the items are applicable and can be scored.
Note that the Bayley Mental, Motor, and Behavior Rating Scales are independent. Thus, missing data on one does not affect the other.
The Bayley examiner is the final arbiter of assessment protocol.
7.3.5 Priority of the BSID-III during the Clinic Visit
The BSID-III should be administered as early as possible in the visit to obtain the child’s optimal response. Best performance is compromised if the child is tired, hungry, or upset.
7.3.6 Interruption of Administration
If the examiner must stop the test, complete the test and score in the usual way when testing resumes (preferably within 2 weeks). Do not repeat items that the child failed in the first administration, unless you determine the child was not making his best effort at the first visit. If the child did not attend or attempt an item, leave that item blank to indicate that it can be repeated. If at the time of the second testing the child enters into another age set for testing, administer the older age set. The entire test can be repeated, if it is determined that the child was not making his/her best effort at the first visit, such as in the case where the child was too ill.
7.3.7 Scoring
Administer the Mental and Motor Scales adhering to the basal and ceiling rules described in the manual. Score C, NC, RF, RPT, and O as explained in the manual. Record the child's scores on the Record Forms. Tally the raw scores for the Mental and Motor Scales. If more than 2 items on a scale are omitted or spoiled, the exam is invalid and should not be scored.
After testing, obtain the child’s date of birth and calculate the child’s chronological age. Refer to Norm Table A.1, Appendix A of the Bayley Manual to transform the total raw scores for mental and motor items to Index scores: Calculate adjusted and unadjusted Index scores using the norm tables for the child’s gestational and chronological ages. Record the raw and adjusted and unadjusted Index scores on the covers of the Record Forms.
Ask the caregiver questions 1 and 2 of the Behavior Rating Scale (BRS) directly after the exam. Complete the BRS as soon as possible after the caregiver and child leave. Do not complete items 3 and 4. Transfer the item scores to the cover of the BRS and sum the appropriate items within each factor and across all items to obtain 3 factor scores. (Total Orientation/Engagement Factor, Total Emotional/Regulation Factor, Total Motor Quality Factor). Add the 3 factor scores, plus the Total Additional Items to obtain the Total Raw Score.
Note that items 19 and 29 are part of 2 factors. They are added into each factor score but one entry of each must be backed out of the total score (see manual). Examiners do not need to obtain the percentile ranks for the factors or total score. Record each of the raw factor scores and the total score on the cover of the Behavior Rating Scale Record Form.
The examiners or site coordinator will enter the summary data onto the Summary Sheet (SUM) for data entry.
7.3.8 Incomplete Exams
The Mental, Motor, and Behavior Rating Scales are independent; thus missing data on one scale does not affect the other. If the examiner omits an item by mistake, the item is given "no credit”. If more than 2 items are omitted, spoiled, or judged to be 'not applicable', the exam is invalid. If the basal and ceiling are not achieved, the exam is invalid. Invalid data should be discarded.
7.3.9 Administration guidelines
Examiners should typically use the child's corrected age to select initial item set, usually the 23-25 months set. However, they should use clinical judgment in selecting the initial item set when a child presents with impairments that are likely to adversely affect the child’s abilities to perform at corrected age.
Administer the mental and motor scales adhering to the basal and ceiling rules in the Bayley manual (p. 44)
Record the child's scores on the BSID-III protocols. Score C, NC, RF, RPT, and O as explained in the manual.
Use the following scripts to control caregiver input into the assessment:
"Thanks for coming in today. I want to explain what I will be doing with ______(child's name). I am going to show him/her different toys and see how he/she responds to them. I will be giving him/her items at his/her age level and above, so I don't expect him/her to know how to do every item today.
I have to present the items in a certain way, with certain instructions, so I will ask that you not repeat the instructions or show him/her what to do. Just make him/her comfortable on your lap. It's O.K. to encourage him/her by saying "Go ahead, you do it".
Also, all the toys are washed and are a safe size (except the red beads) so it's O.K. if things go to the mouth."
It also helps to give reminders to parents before bringing out certain items.
For picture book items and toys that you want child to label say, "I don't want to say the names of these".
For crayon and pencil items, "I don't want to tell him/her what to do with these --" "let's see what he/she does" or "Please don't hold the paper for him/her".
Give gentle reminders as necessary to an over-involved parent.
Encourage the child without over-repetition of instructions prescribed by the manual (e.g. “You’re trying hard”, "Good job", "OK"), rather than comments linked to success.
Examiners may use a flexible order of item administration.
Reference the manual as needed during the administration, but the examiner should know the items well enough not to break the flow if the exam.
Organize test materials to be nearby but out of sight of the child.
Keep test materials and stop watch off the table to avoid distracting the child.
Time appropriate items with a stop watch.
Use the "Bayley" stairs. If Bayley stairs cannot be accommodated due to lack of storage space, other stairs may be used if they are within 1 inch of the description of the Bayley manual.
7.4 Additional guidelines
Refer to the manual regarding all instructions related to equipment, timing, presentation (pegs, boards), teaching, demonstrating, helping, eliciting responses, and interpretation.
7.5 Behavior Observation Inventory
The examiner should respond to each statement that best describes how often the behavior was observed during testing. For the caregiver ratings, the examiner should read the description of each behavior to the caregiver and ask him or her to rate the degree to which each statement is typical of everyday behavior.
7.6 The Modified Checklist for Autism in Toddlers (M-CHAT)
The M-CHAT is a 23-question, parent-report questionnaire designed to identify children at age 24 who are at increased risk of autism spectrum disorders.
For consistency, we would like for the M-CHAT to be completed by the mother, unless the mother is not the primary caregiver.
This Checklist follows the Bayley exam and is administered by the Bayley examiner. The mother is instructed to respond based on “how your child USUALLY is”. If the behavior is rare (i.e., only seen it once or twice), they should be instructed to answer as if the child does NOT do it."
The idea is that there will be no "maybes.” If a parent asks you how to interpret or answer a particular question, remind him/her that what the child USUALLY does deserves a "yes." Do not try to explain a question or expand on it.
All questions should be completed.
CHAPTER 7: Bayley Scales of Infant Development 5/23/07 Page 7 - 2