Used to assess infant and toddler mental and motor development through a series of standardized tasks. From performance on the tasks, a normed developmental quotient is derived for each scale. The Mental Scale is designed to assess a range of responses involving, for example, object permanence, memory, problem solving, and language-related abilities. The Motor Scale assesses both fine and gross motor abilities (including postural control). A third, 30 item, scale, referred to as the Behavior Rating Scale, provides additional information concerning attention, emotional regulation and the quality of movements. More recently, the Bayley-III Cognitive and Language Scales were made available as a means of assessing infants at risk for subsequent developmental problems. There are two other Bayley-II Scales that incorporate parental reports about social responsiveness, imitation, self-control and interactions with other children. All told, the Scales have been validated for children from 1 to 42 months, with the Mental and Motor Scales having high test-retest reliabilities (..83 and .77, respectively). The Scales were originally devised by Nancy Bayley (1899-1994), and first published in 1969.
See Ages and Stages Questionnaire (ASQ), Developmental screening, Developmental readiness, Diagnosis (or diacrisis), Gesell’s Developmental Schedules (or Scales), MacArthur-Bates Child Development Index (CDI), Motor development, Mullen Scales of Early Learning, Object permanence