Bayley Scales of Infant Development
The Bayley Scales of Infant Development (BSID) measure the mental and motor development and test the behavior of infants from one to 42 months of age.
The BSID are used to describe the current developmental functioning of infants and to assist in diagnosis and treatment planning for infants with developmental delays or disabilities. The test is intended to measure a child's level of development in three domains: cognitive, motor, and behavioral.
Cognition can be defined as a process by which knowledge is gained from perceptions or ideas. Cognitive development refers to how an infant perceives, thinks, and gains an understanding of the world. Within the history of developmental psychology, the work of Jean Piaget (1896–1980), the Swiss psychologist, has had the greatest impact on the study of cognitive development. Piaget's theory is focused on the processes of cognitive development and states that the child is born with an innate curiosity to interact with and understand his/her environment. It is through interaction with others that the child actively constructs his/her development.
During the first two years of life, infants grow and develop in many ways. Two types of motor development occur at this stage. Cephalocaudal development occurs in the following sequence: head before arms and trunk and arms and trunk before legs. Proximodistal development occurs as follows: head, trunk, arms before hands and fingers. Motor development has a powerful impact on the social relationships, thinking, and language of infants. Large motor development allows infants to have more control over actions that help them move around their environment, while small motor development gives them more control over movements that allow them to reach, grasp, and handle objects. The sequence of these developments is similar in most children; however, the rate of growth and development varies by individual.
Temperament is the set of genetically determined traits that organize the child's approach to the world. They are instrumental in the development of the child's distinct personality and behavior. This behavioral style appears very early in life—within the first two months after birth—and undergoes development, centered on features such as intensity, activity, persistence, or emotionality.
Besides measuring normal cognitive, motor, and behavioral developmental levels, the BSID are also used in cases in which there are significant delays in acquiring certain skills or performing key activities in order to qualify a child for special interventions. Specifically, they are also used to do the following:
- identify children who are developmentally delayed
- chart a child's progress after the initiation of an intervention progrlim
- teach parents about their infant's development
- conduct research in developmental psychology
The BSID were first published by Nancy Bayley in The Bayley Scales of Infant Development (1969) and in a second edition (1993). The scales have been used extensively worldwide to assess the development of infants. The test is given on an individual basis and takes 45–60 minutes to complete. It is administered by examiners who are experienced clinicians specifically trained in BSID test procedures. The examiner presents a series of test materials to the child and observes the child's responses and behaviors. The test contains items designed to identify young children at risk for developmental delay. BSID evaluates individuals along three scales:
- Mental scale: This part of the evaluation, which yields a score called the mental development index, evaluates several types of abilities: sensory/perceptual acuities, discriminations, and response; acquisition of object constancy; memory learning and problem solving; vocalization and beginning of verbal communication; basis of abstract thinking; habituation; mental mapping; complex language; and mathematical concept formation.
- Motor scale: This part of the BSID assesses the degree of body control, large muscle coordination, finer manipulatory skills of the hands and fingers, dynamic movement, postural imitation, and the ability to recognize objects by sense of touch (stereognosis).
- Behavior rating scale: This scale provides information that can be used to supplement information gained from the mental and motor scales. This 30-item scale rates the child's relevant behaviors and measures attention/arousal, orientation/engagement, emotional regulation, and motor quality.
The BSID are known to have high reliability and validity. The mental and motor scales have high correlation coefficients (.83 and .77 respectively) for test-retest reliability.
BSID data reflect the U.S. population in terms of race, ethnicity, infant gender, education level of parents, and demographic location of the infant. The BSID was standardized on 1,700 infants, toddlers, and preschoolers between one and 42 months of age. Norms were established using samples that did not include disabled, premature, and other at-risk children. Corrected scores are sometimes used to evaluate these groups, but their use remains controversial.
The BSID has poor predictive value, unless the scores are very low. It is considered a good screening device for identifying children in need of early intervention.
Before giving the BSID test to a child, the examiner explains to the parents what will happen during the test procedure. This is to allow the examiner to establish a focused rapport with the child once the procedure has started and avoid diverting attention from the child to the parents during the test. The parents are also asked not to talk to the child during the BSID test to avoid skewing results.
There are no risks associated with the BSID test.
As of 2004 it was recognized that parental involvement in the developmental assessment of their children is very important. First, because parents are more familiar with their child's behavior, their assessment may indeed be more indicative of the child's developmental status than an assessment that is based on limited observation in an unfamiliar clinical setting. The involvement of parents in their child's development testing also improves their knowledge of child development issues and their subsequent participation in required intervention programs, if any. In cases of developmental problems, parents should bear in mind that the scoring and interpretation of the test results is a highly technical matter that requires years of training and experience. Besides the BSID, parents should be aware that three other infant development scales are commonly used:
- Brazelton Neonatal Behavioral Assessment Scale: This scale tests an infant's neurological development, interactive behavior, and responsiveness to the examiner, and need for stimulation. This test is administered during the newborn period only.
- Gesell Developmental Schedules: These schedules test for fine and gross motor skills, language behavior, adaptive behavior including eye-hand coordination, imitation, object recovery, personal-social behavior such as reaction to persons, initiative, independence, and play response.
- Denver Developmental Screening Test: This test is used to identify problems or delays that should be more carefully evaluated. It measures four types of development: personal/social, fine-motor/adaptive, language, and gross motor skills.
Behavior—A stereotyped motor response to an internal or external stimulus.
Cephalocaudal development—Motor development which occurs in the first two years of life: head before arms and trunk, arms and trunk before legs.
Cognition—The act or process of knowing or perceiving.
Cognitive—The ability (or lack of) to think, learn, and memorize.
Motor skills—Controlled movements of muscle groups. Fine motor skills involve tasks that require dexterity of small muscles, such as buttoning a shirt. Tasks such as walking or throwing a ball involve the use of gross motor skills.
Proximodistal development—Motor development which occurs in the first two years of life: head, trunk, arms before hands and fingers.
Stereognosis—The ability to recognize objects by sense of touch.
Temperament—A person's natural disposition or inborn combination of mental and emotional traits.
Amiel-Tison, Claudine, et al. Neurological Development from Birth to Six Years: Guide for Examination and Evaluation. Baltimore, MD: Johns Hopkins University Press, 2001.
Sattker, Jerome M. Assessment of Children: Behavioral and Clinical Applications, 4th ed. Lutz, FL: Psychological Assessment Resources Inc., 2001.
——. Assessment of Children: Cognitive Applications, 4th ed. Lutz, FL: Psychological Assessment Resources Inc., 2001.
Glenn, S. M., et al. "Comparison of the 1969 and 1993 standardizations of the Bayley Mental Scales of Infant Development for infants with Down's syndrome." Journal of Intellectual Disability Research 45, no. 1 (February 2001): 55–62.
Provost, B., et al. "Concurrent validity of the Bayley Scales of Infant Development II Motor Scale and the Peabody Developmental Motor Scales in two-year-old children." Physical and Occupational Therapy in Pediatrics 20, no. 1 (2000): 5–18.
Voigt, R. G., et al. "Concurrent and predictive validity of the cognitive adaptive test/clinical linguistic and auditory milestone scale (CAT/CLAMS) and the Mental Developmental Index of the Bayley Scales of Infant Development." Clinical Pediatrics (Philadelphia) 42, no. 5 (June 2003): 427–32.
American Academy of Child & Adolescent Psychiatry (AACAP). 3615 Wisconsin Ave., N.W., Washington, DC. 20016–3007. Web site: <www.aacap.org>.
American Academy of Pediatrics (AAP). 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: <www.aap.org>.
American Psychological Association (APA). 750 First Street, NE, Washington, DC 20002–4242. Web site: <www.apa.org>.
Child Development Institute (CDI). 3528 E. Ridgeway Road, Orange, CA 92867. Web site: <www.childdevelopmentinfo.com>.
"Assessments for Young Children." LD Online. Available online at <www.ldonline.org/ld_indepth/early_identification/assessment_devareas.html> (accessed November 23, 2004).
Monique Laberge, Ph.D.