Bayley II

Understanding Physical Therapy Outcome Measurements: The Bayley Scales of Infant Development

The Bayley Scales of Infant Development was revised in 1993 and is now known as The Bayley II. This assessment measures not just fine and gross motor skills (such as the PDMS-II), but also monitors mental and cognitive performance as well. The Bayley II is a comprehensive and reliable tool used to measure skills and behavior in children from 0 to 3 years.

The motor portion of the test looks at both fine and gross motor skills, including manipulatory skills, large muscle Bayley IIcoordination, dynamic movement, postural imitation, and stereognosis. The test is used to detect developmental delay and to monitor a child’s developmental progress. The items are arranged by degree of difficulty and uses a pass/fail system for scoring. So how is this test different from the other exams we use to monitor children birth to 3 years old?

Advantages and Limitations of the Bayley II:

Advantages of the Bayley II:

  • Most widely used tool to determine developmental level of infants
  • Most widely utilized assessment in infant research
  • Comprehensive psychometric properties
  • Standardized on a nationally representative sample
  • Takes 20-60 minutes to complete

Limitations of the Bayley II:

  • No sub-scores for individual tests to quantify specific strengths and needs
  • A credit/no credit binary scoring system does not allow a child to be credited for emerging tasks
  • Cognitive items depend on fine motor performance
  • Quality of movement is hard to assess
  • Limited reliability and validity

Physical therapists mostly use the motor subset of the Bayley Scale, assessing gross and fine motor development, and skill acquisition. The Bayley II has been norm-referenced, and proven to be reliable and valid. It is relatively easy to administer and has been helpful in research and physical monitoring related to children with suspected delay.

Does your infant or toddler have special needs? Or do you have more questions about the physical development of your preschooler? Come to see one of our specialists!