Longitudinal observations of individual infant's vocalizations.

Twice a week observation of five infants' vocalizations during the first 30 weeks of life showed that hearing impaired infants displayed different language patterns than normally hearing infants. Developmental differences in vocal activity were observed by six weeks of age, suggesting that hearing impaired infants may differ from unimpaired infants earlier than has been believed.

The within-list distributed practice effect: Tests of the varied context and varied encoding hypotheses.

The present studies provided separate tests of the varied context and varied encoding hypotheses of the MP-DP effect. The investigation of varied encoding used an incidental learning procedure in which the nature of the orienting task was manipulated such that the subject attended to different attributes of words (varied encoding) or only one attribute (same encoding). While the prediction that the recall of MP-DP items should be comparable under comparable levels of encoding was not supported, differences were obtained in recall of items under same and variable orienting task conditions. An MP-DP effect was obtained under the incidental learning procedure. Tests of varied context involved the presentation of target items in list contexts which were the same or different from list contexts on previous occurrences of the item. The prediction that recall of items surrounded by different context should exceed that of items surrounded by the same context was not supported.