A longitudinal sample of 226 infants were tested monthly on habituation and novelty preference tasks, augmented with simultaneous heart rate recording from 3 to 9 months of age. Infants were then administered the Bayley Scales of Infant Development II (BSID) and MacArthur Communicative Development Inventory (MCDI) at 12, 18, and 24 months. Prior findings regarding the decline in look duration with age were replicated. Age‐based factors were extracted from the monthly assessments, an early attention factor from 3 to 6 months and a late attention factor from 7 to 9 months. A novelty preference factor, which grouped recognition performance at 4 and 6 months of age, was also derived. The late attention factor correlated negatively with a factor score derived from the BSID mental index, and the novelty preference aggregate was correlated positively with a factor score derived from the MCDI production scores. Two clusters of infants were derived based on the developmental course of change from the early attention to late attention look duration aggregates: One cluster (n= 150) decreased strongly, and another (n= 50) increased. Infants belonging to these clusters subsequently differed on both the BSID and MCDI outcomes, with the former cluster showing distinct advantages that increased as the outcome assessments progressed from 12 to 24 months of age. This finding was bolstered by subsequent analyses of data from infants who completed all tests run from 3 to 9 months. The results of this study suggest that the developmental course of attention during infancy is an important clue to cognitive and language outcomes in early childhood.

The relationship between children's language acquisition and their nonverbal intelligence has a long tradition of scientific inquiry. Current attention focuses on the use of nonverbal IQ level as an exclusionary criterion in the definition of specific language impairment (SLI). Grammatical tense deficits are known as a clinical marker of SLI, but the relationship with nonverbal intelligence below the normal range has not previously been systematically studied. This study documents the levels of grammatical tense acquisition (for third-person singular -s, regular and irregular past tense morphology) in a large, epidemiologically ascertained sample of kindergarten children that comprises 4 groups: 130 children with SLI, 100 children with nonspecific language impairments (NLI), 73 children with low cognitive levels but language within normal limits (LC), and 117 unaffected control children. The study also documents the longitudinal course of acquisition for the SLI and NLI children between the ages of 6 and 10 years. The LC group did not differ from the unaffected controls at kindergarten, showing a dissociation of nonverbal intelligence and grammatical tense marking, so that low levels of nonverbal intelligence did not necessarily yield low levels of grammatical tense. The NLI group's level of performance was lower than that of the SLI group and showed a greater delay in resolution of the overgeneralization phase of irregular past tense mastery, indicating qualitative differences in growth. Implications for clinical groupings for research and clinical purposes are discussed.

Four-month-old infants (N = 68) were tested in a paired-comparison familiarization-novelty recognition task in which the length of choice trials was systematically manipulated. Peak look duration during pretest and familiarization periods significantly predicted a dichotomous measure of recognition performance, but recognition was unaffected by choice-trial length. Heart rate (HR) was simultaneously assessed during the task, and the amount of time infants spent in various HR-defined phases of attention was assessed. Longer durations of looking during pretest and familiarization were significantly associated with more time spent in both sustained attention (SA) and attention termination (AT). Of these two variables, only individual differences in AT accounted for significant variance in recognition memory performance. A final analysis addressed the possibility that individual differences in AT mediated the relation between look duration and recognition performance. These findings provide support for the hypothesis that individual differences in the disengagement of attention underlie the relation between look duration and cognitive performance in early to midinfancy.

Four-month-old infants were exposed to sequences in which a 2-s light stimulus alternated with dark interstimulus periods whose length was manipulated to be 3 or 5 s. A predictable on-off pattern occurred for eight trials, but the light stimulus was omitted on the ninth trial. Infants showed heart rate responses on the omission trial that were closely synchronized with the expected recurrence of the stimulus. In addition, these heart rate patterns were observed predominantly in infants who had previously shown high levels of sustained attention in pretests with visual stimuli. These findings indicate remarkable precision in infants' estimation of time intervals, and suggest that the link between time estimation and attentional processes is present in early infancy.

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