M van den Hof | PubMed Health

PubMed1991

What has happened to Prägnanz? Coding, stability, or resonance.

Three theoretical measures of Prägnanz were compared with four data sets. The theoretical measures were a stimulus-coding one (structural information load, SIL), a measure related to within memory processes (stability), and one based on the interaction of perception and memory (resonance). The four data sets were obtained in two experiments and involved goodness rating, grouping, and immediate and delayed recall. A complete set of seven-element binary serial patterns was used in each experiment. Both SIL and resonance were shown to correlate reliably with the data sets across tasks. The resonance measure, however, performed best. Prägnanz thus appears to be explained better by resonance than by stimulus coding or memory storage. Resonance explained all systematic variance in the recall tasks, but not in the other tasks. Regarding these, partial-correlation analyses showed that the effect of stability could be fully reduced to resonance. SIL could not be similarly reduced. Therefore, additional perceptual constraints, other than resonance, would be needed for a complete account of goodness in the judging or grouping tasks.

Adult↗

PubMedDate not supplied

Semi-Fowler's positioning, lateral tilts, and their effects on nonstress tests.

OBJECTIVE: To determine whether a lateral tilt for women in semi-Fowler's position for antepartum nonstress tests (NSTs) (a) promotes NST reactivity or (b) shortens testing time required to obtain a reactive tracing. SETTING: An antepartum fetal assessment unit of a tertiary care facility in eastern Canada. DESIGN: In this prospective, randomized study, a computer analysis of the NSTs was used to obtain an objective, standardized interpretation of fetal heart rate reactivity. Participants were randomly assigned to two experimental groups using semi-Fowler's position with a 45-degree tilt to either the left or right, or to a control group using semi-Fowler's position with no lateral tilt. PARTICIPANTS: A convenience sample of 823 nonstress tests was obtained from women with singleton pregnancies, intact amniotic membranes, and gestations between 32 and 42 weeks. The final sample available for analysis totaled 738 nonstress tests from 573 pregnancies. MAIN OUTCOME MEASURES: Percentage of reactive nonstress tests and the number of minutes required for tests to be reactive. RESULTS: The rate of reactive NSTs and the time to achieve a reactive NST did not differ statistically for any of the three study groups. Likewise, NST outcomes were similar when the left-tilt group was compared with the right-tilt group. Although no significant differences were found between study groups, less than 2% of the women in the control group (semi-Fowler's position without a lateral tilt) experienced symptoms consistent with supine hypotensive syndrome. CONCLUSIONS: No statistically or clinically significant differences were found in nonstress tests between the three groups. Lateral tilting did not shorten test time. Results do suggest that hemodynamic changes can occur in 3rd trimester women who are in semi-Fowler's position without a lateral tilt. Lateral tilting of gravidas in semi-Fowler's position during nonstress testing is thus supported to avoid hypotensive symptoms.

Adolescent↗