Object Permanence and the Relationship to Sitting Development in Infants With Motor Delays.
Mihee An, Emily C Marcinowski, Lin-Ya Hsu and 8 others
PMID 35653237WHAT IT FOUND
Infants with motor delays showed delayed object permanence, matching typical peers in skill but occurring about 5 months later.
Object permanence improved as sitting skills developed, with strong correlations between the two. The new Object Permanence Scale reliably tracked this progression using simple toys.
Key findings
01Object permanence scores correlated strongly with sitting skills in infants with motor delays across all four visits (r = 0.584 to 0.715).
02Infants with motor delays were approximately 5 months older than typically developing peers when reaching similar object permanence scores at the onset of sitting.
03The Object Permanence Scale demonstrated excellent interrater reliability (ICC 0.92) and moderate to good validity against the Bayley-III cognitive scale (r = 0.554).
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
Typically developing infants were recruited from only one site, while infants with motor delays came from five geographic areas. Families had higher incomes than the general population, limiting generalizability. Concurrent validity was only tested in the motor delay group due to missing Bayley-III data for the typical group. Interrater reliability may be overestimated because raters scored videos rather than live assessments. The OPS is an ordinal scale, so score differences do not represent equal increments of skill.
Declared interests
The authors declare no conflicts of interest.
The easy way to misread this
Do not interpret OPS scores as age-equivalent or normative data. The scale is ordinal and was developed for this specific population, so a score of 6 does not mean the infant performs like a typical 6-month-old. Use it to track individual progress over time, not to compare against typical developmental milestones.