What was observed about Hopi infants placed on cradleboards until their first birthday?

Infants in the Hopi culture placed on cradleboards until their first birthday have been observed to develop motor skills in the typical sequence expected for infants. This finding suggests that the use of cradleboards does not negatively impact the developmental progression of motor skills. Such traditional practices allow infants to be securely positioned while still facilitating sensory experiences and social interactions, which are critical for motor development.

The standard pattern of motor skill acquisition reflects that these infants are engaging with their environment appropriately, despite being in a restrained position. This observation highlights the importance of specific cultural practices on development and reinforces that variations in child-rearing can coexist with normative developmental milestones.