Action production influences 12-month-old infants' attention to others' actions

Recent work implicates a link between action control systems and action understanding. In this study, we investigated the role of the motor system in the development of visual anticipation of others' actions. Twelve-month-olds engaged in behavioral and observation tasks. Containment activity, infants' spontaneous engagement in producing containment actions; and gaze latency, how quickly they shifted gaze to the goal object of another's containment actions, were measured. Findings revealed a positive relationship: infants who received the behavior task first evidenced a strong correlation between their own actions and their subsequent gaze latency of another's actions. Learning over the course of trials was not evident. These findings demonstrate a direct influence of the motor system on online visual attention to others' actions early in development.     

Effects of atropine on the repeated acquisition and performance of response sequences in humans.

The present study assessed a 24-hr time course for the acute effects of intramuscular injections of atropine sulfate (0, 1.5, 3.0, and 6.0 mg/70 kg) in healthy adult humans responding under a two-component multiple schedule of repeated acquisition and performance of response sequences. Subjects resided in an inpatient research ward for the duration of the study. In each component of the multiple schedule, subjects completed a different sequence of 10 responses in a predetermined order using three keys of a numeric keypad. In the acquisition component, the subjects' task was to acquire a new sequence each session. Eight sessions were conducted daily: one immediately before administration of the drug and then 0.5, 1.5, 3.0, 5.0, 7.0, 9.0, and 24.0 hr after administration. In the performance component, the response sequence always remained the same. Overall percentage of errors increased and overall response rates decreased in the acquisition and performance components as an orderly function of drug dose. However, these effects were selective in that behavior in the acquisition component generally was affected at lower doses than in the performance component. When behavior was affected in both the acquisition and performance components, the time courses of effects were similar. Drug effects began at 0.5 or 1.5 hr, reached peak effects between 3.0 and 5.0 hr, and returned to placebo levels between 7.0 and 9.0 hr postdrug in both schedule components. None of the drug doses produced reliable effects the day after drug administration (24-hr postdrug) in either schedule component. The present study provides the first within-subject assessment of the magnitude and duration of the effects of an anticholinergic on repeated acquisition and performance baselines and extends to atropine the selective effects on these two baselines demonstrated previously with other compounds in humans and nonhumans.     

Medicine as a career: Choices and consequences

Medicine has traditionally been regarded as a rewarding career both financially and socially. How true, however, is that tradition in today's world of rising costs and decreasing revenues? The educational debt of the physician-in-training is steadily increasing, and currently does not affect specialty choice. As the cost of medical education continues to rise, the applicant pool begins to shrink, thereby possibly affecting the quality of future physicians. Once the physician has completed training however, the majority enjoy a positive return on investment. Their incomes generally fail to remain ahead of inflation, and therefore, have remained within a narrow band of $40,000 in 1970 dollars. Finally, the demand for physician services cannot be attributed solely to either the consumer (patient) or to the supplier (physician). Rather, the demand for medical services appears to be a unique combination of the two. In conclusion, medicine still is an attractive career path, but the choices and consequences are becoming much more demanding.     

On the greatest lower bound to reliability

Certain ambiguities in a recent paper on the computation and statistics of the greatest lower bound are clarified.     

Age and health care beliefs: self-efficacy as a mediator of low desire for control

The relation between individuals' age, desire for control, information, and perceived self-efficacy was examined using a cross-sectional comparison of 116 noninstitutionalized adults, ages 20 to 99. We found that individuals over 60 years of age desired less health-related control than did younger adults, and preferred that health professionals make decisions for them. Differences in desire for health-related information were in the same direction but were not significant. Older adults also desired less control in general day-to-day living. Perceived self-efficacy was also lower for individuals over 60 years of age. Results suggested that perceived self-efficacy mediated the age differences in health-related desire for control. Mediation of general desire for control, however, was not strong. Cohort and developmental explanations are provided for these findings. It is suggested that those individuals most at risk for chronic illnesses and hospitalization are also those who are most likely to fail to take an active role in their health care.     

Some developments in multivariate generalizability

This article is concerned with estimation of components of maximum generalizability in multifacet experimental designs involving multiple dependent measures. Within a Type II multivariate analysis of variance framework, components of maximum generalizability are defined as those composites of the dependent measures that maximize universe score variance for persons relative to observed score variance. The coefficient of maximum generalizability, expressed as a function of variance component matrices, is shown to equal the squared canonical correlation between true and observed scores. Emphasis is placed on estimation of variance component matrices, on the distinction between generalizability- and decision-studies, and on extension to multifacet designs involving crossed and nested facets. An example of a two-facet partially nested design is provided.Appreciation is expressed to the Office of Research in Medical Education, University of Texas Medical Branch, for permitting use of their data.     

A simple test for heterogeneity of variance in complex factorial designs

A simple procedure for testing heterogeneity of variance is developed which generalizes readily to complex, multi-factor experimental designs. Monte Carlo Studies indicate that the Z-variance test statistic presented here yields results equivalent to other familiar tests for heterogeneity of variance in simple one-way designs where comparisons are feasible. The primary advantage of the Z-variance test is in the analysis of factorial effects on sample variances in more complex designs. An example involving a three-way factorial design is presented.     

Factors Related to Career Aspirations of New Entrants into a Stratified Occupational System

A transactional model of career aspirations is presented. Selected variables from the model were measured with a postal questionnaire completed by 346 new entrants into a stratified occupational system. Factors found to be strongly related to initial career aspiration levels included sex and educational qualifications. These variables were found to mediate other factor relationships with career aspirations.     

Perception of acoustic correlates of major phrasal units by young infants.

How might young learners parse speech into linguistically relevant units? Sensitivity to prosodic markers of these segments is one possibility. Seven experiments examined infants' sensitivity to acoustic correlates of phrasal units in English. The results suggest that: (a) 9 month olds, but not 6 month olds, are attuned to cues that differentially mark speech that is artificially segmented at linguistically COINCIDENT as opposed to NONCOINCIDENT boundaries (Experiments 1 and 2); (b) the pattern holds across both subject phrases and predicate phrases and across samples of both Child- and Adult-directed speech (Experiments 3, 4, and 7); and (c) both 9 month olds and adults show the sensitivity even when most phonetic information is removed by low-pass filtering (Experiments 5 and (6). Acoustic analyses suggest that pitch changes and in some cases durational changes are potential cues that infants might be using to make their discriminations. These findings are discussed with respect to their implications for theories of language acquisition.     

A tactile stimulation device for measuring two-point and gap discrimination thresholds in humans

A device to measure two-point-discrimination and gap-discrimination thresholds is described. The apparatus is capable of controlled and reliable delivery of forces up to 42.50 g while determining point of skin contact and subsequent depth of skin indentation during threshold determination. Stimulus delivery is controlled by computer software that deactivates a solenoid, allowing a counterbalanced beam with one of two stimulus wheels mounted on its end to rise and stimulate the skin. Depth of skin indentation is recorded by hardware that monitors the output of a photocell reflecting the position of the beam. The apparatus allows complete computer control of all data acquisition and recording.