What is the Bayley-4?
The Bayley Scales of Infant and Toddler Development, now in their fourth edition, are widely regarded as the clinical reference standard for assessing development in the first three-and-a-half years of life. Administered by a trained clinician, the Bayley-4 produces detailed scores against a norming sample of 1,700 US children.
How it is structured
It spans seven subscales — Cognitive, Receptive and Expressive Communication, Fine and Gross Motor, Social-Emotional, and Adaptive Behavior. Together they give one of the most complete pictures of early development in clinical use.
How Learning Curve represents it
The Bayley-4 is a proprietary instrument, so Learning Curve holds none of its actual test items. What appears here is a representative set of paraphrased behavioural constructs across all seven subscales — plain-language descriptions grounded in published validation studies and widely-reported developmental norms, with attribution. It is a coverage sample, not the full test, and it serves as a normative reference point rather than a reproduction of the instrument.