Biomedical subjects

S Wiens

Publications and source records attributed to S Wiens.

9 recordsLinked to original sources

PubMed2001

Quadratic trend analysis and heartbeat detection.

In heartbeat detection tasks based on the Method of Constant Stimuli (MCS), subjects judge the simultaneity between their heartbeats and stimuli presented at six intervals ranging from 0 to 500 ms after the R-waves on an electrocardiogram. Because research suggests that subjects do not perceive stimuli at 0 or 500 ms as simultaneous, individual performance was indexed with quadratic trend analysis to test for distributions of simultaneity judgments across intervals that peak between 0 and 500 ms. Further, because some tasks use only two intervals, performance was also indexed using intervals of either 0 and 200 ms or 200 and 500 ms. Continuous performance scores from quadratic trend and two-interval analysis tended to correlate more highly with variables previously shown to correlate with heartbeat detection than scores from the commonly-used chi(2) analysis. These findings support the use of both quadratic trend analysis and two-interval tasks for assessing heartbeat detection ability.

Adolescent↗

PubMed2001

Nonconscious fear conditioning, visceral perception, and the development of gut feelings.

When people are presented with backward-masked images of fear-relevant stimuli and only some of these images are paired consistently with electric shocks, they can predict the occurrence of shocks even though they do not consciously know which images they have seen. We postulated that they may use the perception of visceral cues from the conditional fear response to facilitate the prediction of shocks. In this study, ability to detect heartbeats was used to index sensitivity to visceral cues. The results showed that subjects who could detect their heartbeats performed better than chance in predicting whether or not they would receive a shock during the conditioning task. The findings support the notion that hunches, or "gut feelings," are based in part on the perception of visceral cues.

Adolescent↗

PubMed2000

Cardiovascular reactivity and adaptation to recurrent psychological stress: the moderating effects of evaluative observation.

The impact of evaluative observation on cardiovascular reactivity and adaptation to recurrent psychological stress was evaluated in 162 undergraduate men and women. All participants performed three mental arithmetic tasks with or without evaluative observation. Impedance cardiographic, blood pressure, task performance, and stress appraisal measures were recorded for each task. Evaluative observation moderated the effects of task repetition on cardiac reactivity but not vascular reactivity. The introduction of evaluative observation disrupted cardiac adaptation, resulting in a resurgence of beta-adrenergic cardiac reactivity (p < .005), whereas the removal of evaluative observation promoted cardiac adaptation. Evaluative observation also increased stress appraisals and slowed task performance. The results support the dual process theory of habituation, rather than stimulus comparator theory, but only partially support cognitive appraisal theory.

Adaptation, Psychological↗

PubMed1999

Synthetic stimuli attenuate the effect of attention on the dichotic right-ear advantage.

This study assessed attentional effects on the right-ear advantage (REA) for a dichoticlistening task that used synthetic-speech syllables. Presenting subjects with monaural tone cues at various intervals prior to dichotic pairs of natural-speech syllables, T. A. Mondor and M. P. Bryden 1991 (The influence of attention on the dichotic REA. Neuropsychologia, 29, 1179-1190) found a reduced REA with longer intervals. This suggested that tone cues at longer intervals helped overcome a right-ear attentional bias. Despite sufficient statistical power, in the present study no reduction in the REA was found with longer intervals between tones and synthetic-speech syllables. As synthetic-speech stimuli tend to fuse better into the percept of a single stimulus than do natural-speech stimuli, attentional effects on the REA may be reduced with dichotic stimuli that fuse.

Adult↗

PubMed1999

Cardiovascular reactivity and adaptation to recurrent psychological stress: effects of prior task exposure.

The effects of prior task exposure on cardiovascular reactivity to stress were examined in two experiments by randomly assigning participants to repeated exposure groups that performed mental arithmetic pretest and test tasks versus delayed exposure groups that performed only the test task after prolonged rest. Impedance cardiographic and blood pressure measures were recorded continuously from 60 undergraduate men in Experiment 1 and 112 undergraduate men and women in Experiment 2. Task repetition attenuated cardiovascular reactivity and improved task performance in repeated exposure groups (p < .001), suggesting an integrated process of behavioral adaptation. During the test task, delayed exposure groups showed greater cardiac reactivity (p < .01), but not vascular reactivity, than repeated exposure groups. Thus, cardiac reactivity varied as a specific function of prior task exposure, whereas vascular reactivity varied as a general function of time.

Adaptation, Psychological↗

PubMed1998

Stability of total respiratory resistance under multiple baseline conditions, isometric arm exercise and voluntary deep breathing.

Little is known about total respiratory resistance (TRR) as a psychophysiological parameter in normal subjects. Therefore, we investigated TRR in 45 healthy students under multiple baseline conditions, isometric arm muscle tension and voluntary deep breathing (VDB). TRR was measured by the forced oscillation technique. In addition, heart rate (HR) as well as volume and time components of the respiratory cycle, respiratory timing and respiratory drive were monitored. Subjects repeated the protocol 14 days later. Coefficients of stability and dependability were calculated for 20 s measurement epochs within and between both sessions. Increases of HR and shortening of time components of the respiratory cycle were found during muscle tension, prolongation of time components and increases in volume were found for deep breathing. During both experimental tasks TRR increased significantly. Short-term as well as long-term stability of absolute TRR scores proved to be comparable or even better than reliability of other physiological parameters, however, difference scores from baseline revealed only low coefficients.

Adult↗

PubMed1998

The ensemble-averaged impedance cardiogram: an evaluation of scoring methods and interrater reliability.

The interrater reliability and concurrent validity of two methods of scoring the ensemble-averaged impedance cardiogram were evaluated. Impedance cardiographic and electrocardiographic signals were recorded from 40 undergraduate men and women during a baseline rest period and a vocal mental arithmetic task period. Recordings were scored by four rates using a conventional method, involving ensemble averaging after careful editing of beat-to-beat waveforms, and a streamlined method, involving ensemble averaging without beat-to-beat editing. Intraclass correlations for interrater reliability exceeded .92, whereas intraclass correlations for concurrent validity exceeded .97, indicating excellent agreement between rates and scoring methods for all cardiac measures. The streamlined method was significantly faster than the conventional method. The results indicate that variations in beat-to-beat editing do not constitute a serious source of error in the ensemble-averaged impedance cardiogram and support the interrater reliability and concurrent validity of the two scoring methods.

Adult↗

PubMed1997

Response bias affects perceptual asymmetry scores and performance measures on a dichotic listening task.

A dichotic listening paradigm discussed by Sidtis and Bryden (Neuropsychologia, 1978, 16, 627-632) allows one to present non-verbal as well as verbal material. This paradigm also permits signal-detection analyses to separate response biases from discrimination abilities. The present study used Sidtis' (Neuropsychologia, 1981, 19, 103-112) Complex Tone Task as an example of the paradigm. Employing signal-detection analyses, we demonstrated that commonly used performance and asymmetry indices are confounded by response bias. Several indices based on signal-detection measures are suggested to replace current widely used measures. As pointed out by Bryden and Sprott (Neuropsychologia, 1981, 19, 571-581), currently the usefulness of a perceptual asymmetry score is mainly determined by mathematical and statistical properties rather than by a theoretical framework. Thus, the choice of a particular index based on signal-detection theory is arbitrary. The present results and those of Katsuki et al. (Journal of Speech and Hearing Research, 1984, 27, 444-448) suggest that the confounding effect of response bias may be present in a variety of experiments investigating lateral processing.

Adolescent↗

PubMed1990

[Postoperative analgesics consumption].

Prescription habits, dose and form of application of analgesics were investigated in a retrospective study of postoperative pain alleviation involving 250 patients. On the basis of clinical and pharmacological criteria, a prescription regime is presented for Paracetamol as used singly and in combination with Codeine. The prescription regime has been tested in a prospective study involving 50 patients and found to be effective.

Acetaminophen↗