Effect of a terminal constraint on control of balance during sit-to-stand

The speed at which sit-to-stand (STS) motions are performed and the subsequent terminal constraint upon upright stance can present subjects with contradictory goals. Previous findings suggested that subjects might adopt a strategy of limiting the peak horizontal momentum of the center of mass (CM), and perhaps of body segments as well, regardless of the speed of ascent. The primary purpose of this study was to test the hypothesis that the limitation in CM momentum is related to the constraint on upright stance at the termination of the task. The secondary purpose was to describe the contribution of the shank, thigh, and upper body (head-arm-trunk) to the peak horizontal momentum of the CM under each test condition. Nine healthy adult males rose from a seated position under the following three conditions: (a) at natural speeds (natural STS); (b) as fast as possible (fast STS); and (c) as fast as possible, followed by falling forward while keeping the feet fixed and using the arms on a support bar to stop the fall (fast STS+fall). The results showed that the peak horizontal momentum of the CM did not change substantially from the natural to fast STS, but increased significantly from the fast STS to the fast STS+fall. These findings are consistent with the hypothesis that limiting peak horizontal momentum of the CM may reflect a movement control strategy related to maintaining equilibrium at the termination of the voluntary task of rising from a chair. The momentum profile of the upper body, but not of the thigh or shank, remained constant across all experimental conditions, suggesting that the motion of the upper body may be tightly controlled in STS, regardless of the altered constraint on balance.     

Education and testing strategy for large-scale cystic fibrosis carrier screening

Population-based screening for cystic fibrosis carrier mutations presents a number of challenges for genetic counselors, owing primarily to the inability of current DNA testing technology to identify all possible mutations and the difficulty involved in conveying the concept of residual risk to those patients who test negative. To address these issues, we are conducting a pilot study, as part of a consortium established by the National Center for Human Genome Research, to explore the efficacy, acceptance, and psychosocial impact of various approaches to carrier screening in an ethnically diverse Southern California population. This article reports the patient instructional and screening strategies we developed in the initial phase of the project in order to optimize our chances of answering these questions and delivering this service on a large scale.     

Measuring behavioral, biosocial, and attitudinal correlates of fertility regulation

A theoretical base consisting of 17 hypotheses was constructed to identify attitudinal, behavioral, and biosocial characteristics of families successful in fertility control. A multiple-choice instrument entitled Rating of Self Status International (ROSSI) was devised to measure attitudinal and behavioral characteristics postulated by the hypotheses. Factor analysis of ROSSI, based on the responses of 297 undergraduates (192 women and 105 men) at a Midwestern university, identified 12 factors that corresponded with one or more of the nondemographic constructs embodying the hypotheses. A quasi-experimental design was outlined that could be used to conduct a crucial test of both the theory and the instrument offered for measuring the theoretical constructs pertinent to fertility control and regulation.     

Attributional style and the generality of learned helplessness

According to the logic of the attribution reformulation of learned helplessness, the interaction of two factors influences whether helplessness experienced in one situation will transfer to a new situation. The model predicts that people who exhibit a style of attributing negative outcomes to global factors will show helplessness deficits in new situations that are either similar or dissimilar to the original situation in which they were helpless. In contrast, people who exhibit a style of attributing negative outcomes to only specific factors will show helplessness deficits in situations that are similar, but not dissimilar, to the original situation in which they were helpless. To test these predictions, we conducted two studies in which undergraduates with either a global or specific attributional style for negative outcomes were given one of three pretreatments in the typical helplessness triadic design: controllable bursts of noise, uncontrollable bursts of noise, or no noise. In Experiment 1, students were tested for helplessness deficits in a test situation similar to the pretreatment setting, whereas in Experiment 2, they were tested in a test situation dissimilar to the pretreatment setting. The findings were consistent with predictions of the reformulated helplessness theory.     

On the nature of the probe reaction-time task to uncover the attentional demands of movement

McLeod (1980) reported some findings which showed that no phase of a movement was more attention-demanding than the other phases, contrary to all the results previously reported (e.g., Ells, 1973; Glencross, 1980). However, McLeod used a paradigm in which the two tasks were serial. Each task consisted of a series of 50 reaction time (RT) trials and/or 50 aiming movement trials. In addition to this, the interval of time between a response and the following signal within each series was constant. In order to try to replicated McLeod's findings, two experiments were conducted in which the response-signal interval was manipulated. The hypothesis was that time certainty associated with a constant interval would facilitate the allocation of time and would thus artificially reduce the interference between tasks. In Experiment 1, manual responses were used for the RT task; in Experiment II, they were vocal. Manipulation of the response-signal interval does not change one of the conclusions reached by McLeod: when the RT task involves vocal responses and the results on the RT task are analyzed in terms of response rather than stimulus arrival during the movement, then there is no phase of the movement which is more attention-demanding than the other phases. However, the results of Experiment II in which both the vocal RT task and the movement task significantly deteriorated in the dual-task condition were taken as an indication that the movement studied involved central attentional demands.     

Maternal interactive behaviour towards children with and children without cleft lip and palate

The present study examined qualitative and quantitative differences in maternal interactive behaviour towards infants with and without cleft lip and palate (CLP). Thirty-three mother-child pairs with CLP and 34 pairs without CLP were videotaped at 3, 6, 9, and 12 months of age in two sorts of play situations at home. In addition, the mothers were questioned by letter about their ability to recognize and interpret the child's signals; their willingness to respond to such signals; and the duration of shared daily activities in the context of feeding and play. The results showed that mothers of CLP children are somewhat less sensitive than other mothers. In addition, it appeared that CLP children play less with other people. Longer feeding times for CLP children appeared to be restricted to the age of 3 months. It is suggested that mothers of CLP children may be comparatively directive and stimulating because of uncertainty about additional deficiencies. Furthermore, they may be inclined to keep their children away from the outside world.     

Counting knowledge and skill in cognitive addition: a comparison of normal and mathematically disabled children.

The relationship between counting knowledge and computational skills (i.e., skill at counting to solve addition problems) was assessed for groups of first-grade normal and mathematically disabled (MD) children. Twenty-four normal and 13 MD children were administered a series of counting tasks and solved 40 computer-administered addition problems. For the addition task, problem-solving strategies were recorded on a trial-by-trial basis. Performance on the counting tasks suggested that the MD children were developmentally delayed in the understanding of essential and unessential features of counting and were relatively unskilled in the detection of certain forms of counting error. On the addition task, the MD children committed many more computational errors and tended to use developmentally immature counting procedures. The immature counting knowledge of the MD children, combined with their relatively poor skills at detecting counting errors, appeared to underlie their poor computational skills on the addition task. Suggestions for future research are presented.     

New measures for assessing alcohol and drug abuse with the MMPI-2: The APS and AAS.

We introduce two new scales for assessing substance abuse problems with the Minnesota Multiphasic Personality Inventory-2 (MMPI-2): the Addiction Potential Scale (APS), a 39-item empirically derived scale, developed by contrasting the responses of a large residential substance abuse sample with responses from both normative and psychiatric control groups; and the Addiction Acknowledgement Scale (AAS), a 13-item face-valid scale, constructed rationally and with attention to internal consistency. Both new scales are shown to discriminate well between groups and substantially better than other selected substance abuse scales. Covariation between the scales and joint effectiveness are examined. Finally, limitations for their practical utility are expressed, and considerations for future research are identified.     

Visual scanning with or without spatial uncertainty and divided and selective attention.

An experiment was conducted to address the relation between theories of selective attention and theories of divided attention by examining the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding their possible differential effects on interference with other concurrent processes. The experiment required the subjects to perform a primary tracking task, which was concurrently performed with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks was displayed with or without spatial uncertainty. The results provide evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with verbal tasks. Furthermore, spatial uncertainty in scanning is identified to be the crucial factor in producing this differential effect.