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W Hager

Publications and source records attributed to W Hager.

87 records · Page 5Linked to original sources
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Different determination of sinoatrial conduction time (SACT) in man.

Using intracardiac recordings of electrical activity and programmed electrical right atrial stimulation of the human heart, the sinoatrial conduction time (SACT) in the method of Strauss et al. 1973 (SACTc) was calculated in 80 patients with and without disturbances of rhythm and compared to the modified measurement of the SACT in the method reported by Narula et al. in 1978 (SACTN). The number of continuously stimuli varied from 4, 8 and 16 stimuli with a frequency of 10% just above the averaged spontaneous frequency. The best correlation was found between the SACTc and the SACTN16 (r = 0.74; p less than 0.001) with a regression line of: SACTN16 = 1.04 SACTc + 28.6. Under these conditions, as opposed to SACTN4 or SACTN8, the most favourable reproducibility and relative coefficient of variation (rVk) could be observed: SACTN16: rVk = 9.5%; r = 0.91; SACTN8: rVK = 12.3%; r = 0.89; SACTN4: rvK = 24.3%; r = 0.53. Higher individual values for SACTN16 were found by continuous atrial stimulation as compared to other methods of determination indicating mainly a higher depression of sinus node automaticity due to overdrive suppression. Under parasympathicolysis (1 mg atropine) the lowest values of SACT were found for SACTN4 (45.9 +/- 20.7 ms) coming closest the "true" SACT, since these conditions neither an increase of the refractory period nor an overdrive suppression exert an influence.

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[Recall and reproduction of words: age-dependent activation of context information in recalling episodic memory contents].

Older people tend to have more problems with the retrieval of episodic memory contents than younger people. One hypothesis to explain this phenomenon refers to age deficits in activating specific pieces of contextual information concerning the learning episode. This hypothesis was submitted to an experimental test for 60 old (about 70 years) and 60 young (about 25 years) adults using the recognition failure paradigm. In this paradigm memory performance is assessed by a cued recall test as well as by an unexpected recognition test. The amount of recognition failure served as the central dependent variable; the length of the retention interval and a strategy instruction (given vs not given) were manipulated as independent variables. Various predictions were derived from the central hypothesis and from typical findings in the literature. They are tested by means of statistical hypotheses on planned a priori contrasts. On the whole, the results confirm the hypothesis concerning age deficits in activating context information during retrieval. Implications for models of gerontological changes in episodic memory are discussed within the framework of Tulving's Synergistic Ecphory model.

Adult↗
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[Cognitive training and strategy behavior: comparative evaluation of 2 cognitive training programs].

Combining a non-comparative with a comparative evaluation, two modern programs for fostering inductive reasoning, namely the German version of the "Cognitive training for children" by Klauer and Phye (1994; Klauer 1989), and the "DenkMit" by Sydow and Meincke (1994), are compared to each other and to a control program which intends to enhance aspects of memory instead of inductive reasoning. The programs were performed with N = 49 children between six and eight years who had been postponed from regular school because of various reasons or who had been selected as especially in need for particular interventions from first classes. Besides the psychometric test often used for assessing inductive reasoning, i.e. three subtests of the German form of the Culture Fair Test by Cattell (Weiss a. Osterland 1980), tasks of concept formation were applied for assessing changes in strategic behavior of children--a type of task which has been used in connection with inductive reasoning since many years. Counter to expectations, the children whose memory was trained, showed changes in performance in the psychometric test in a similar size as the children whose inductive reasoning was trained. These effects are interpreted in terms of special attention directed to the children during the intervention situation. Moreover, it was found that despite the authors claim to the opposite the DenkMit did not cause any changes in visual perception. In contrast to the author's intentions, the "Cognitive Training for Children" did cause some substantive changes in the area of visual perception. The pattern of results with the concept formation tasks, however, overall indicates that the reasoning programs caused some changes in strategic behaviors of the children. Although these changes are not very impressive, they cannot be attributed to extraneous factors such as special attention.

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