An instrument for the measurement of infant-adult synchrony.

The Dyadic Mini Code (DMC) is designed to measure levels of synchrony in early infant-adult interaction. Based on important components of synchronous interaction reported in the literature, the instrument consists of six items, a total score, and a summary rating. Videotapes of 38 term and preterm mother-infant pairs were studied to establish reliability and validity of the tool. Interrater reliability was determined using Cohen's kappa and percent of agreement; kappa was .86 for the total score and ranged from .63 to .92 for each of the six items. A discrimination index, applied to each item, indicated that four items are good predictors of the final rating and two require further testing. Dyadic Mini Code summary ratings compared to mean coherence values computed from Monadic Phase Scale (Tronick, Als, & Brazelton, 1980) scores on the same data yielded moderate concurrent validity; point bi-serial analysis, rpb = .488, p less than .01; and chi 2 = 4.878, df = 1, Fisher's exact test (1-tail) = p less than .05. Construct validity was demonstrated by finding that the instrument discriminated between preterm and term dyads according to expected differences, chi 2 = 4.071, df = 1, Fisher's exact test (1-tail) = p less than .05. Further refinement of the DMC is indicated.