Biomedical subjects

Alan B Cobo-Lewis

Publications and source records attributed to Alan B Cobo-Lewis.

3 recordsLinked to original sources

PubMed2003

Final Syllable Lengthening (FSL) in infant vocalizations.

Final Syllable Lengthening (FSL) has been extensively examined in infant vocalizations in order to determine whether its basis is biological or learned. Findings suggest there may be a U-shaped developmental trajectory for FSL. The present study sought to verify this pattern and to determine whether vocal maturity and deafness influence FSL. Eight normally hearing infants, aged 0;3 to 1;0, and eight deaf infants, aged 0;8 to 4;0, were examined at three levels of prelinguistic vocal development: precanonical, canonical, and postcanonical. FSL was found at all three levels suggesting a biological basis for this phenomenon. Individual variability was, however, considerable. Reduction in the magnitude of FSL across the three sessions provided some support for a downward trend for FSL in infancy. Findings further indicated that auditory deprivation can significantly affect temporal aspects of infant speech production.

Deafness↗

PubMed2003

The temporal coordination of early infant communication.

The ability to coordinate expressive behaviors is crucial to the development of social and emotional communication. Coordination involves systematic sequencing of behaviors from two different modalities that have some temporal overlap. A bootstrapping procedure was used to determine whether preverbal 3- and 6-month-old infants sequence vocalizations, gazes at their mothers' faces, and facial expressions into pairs of coordinated patterns nonrandomly. Smiles and frowns were highly coordinated with vocalizations. Smiles were also coordinated with gazes at mothers' faces, which became stronger with age. Vocalizations were not coordinated with gazes at mothers' faces. These findings illustrate the manner in which infants temporally coordinate communicative actions and provide new evidence that facial expressions (particularly smiles) are central to early infant communications.

Age Factors↗

PubMed2002

Two-dimensional motion perception without feature tracking.

Feature-tracking explanations of 2D motion perception are fundamentally distinct from motion-energy, correlation, and gradient explanations, all of which can be implemented by applying spatiotemporal filters to raw image data. Filter-based explanations usually suffer from the aperture problem, but 2D motion predictions for moving plaids have been derived from the intersection of constraints (IOC) imposed by the outputs of such filters, and from the vector sum of signals generated by such filters. In most previous experiments, feature-tracking and IOC predictions are indistinguishable. By constructing plaids in apparent motion from missing-fundamental gratings, we set feature-tracking predictions in opposition to both IOC and vector-sum predictions. The perceived directions that result are inconsistent with feature tracking. Furthermore, we show that increasing size and spatial frequency in Type 2 missing-fundamental plaids drives perceived direction from vector-sum toward IOC directions. This reproduces results that have been used to support feature-tracking, but under experimental conditions that rule it out. We discuss our data in the context of a Bayesian model with a gradient-based likelihood and a prior favoring slow speeds. We conclude that filter-based explanations alone can explain both veridical and non-veridical 2D motion perception in such stimuli.

Adult↗