Infant visual acuity as a function of viewing distance.     

P Salapatek  A G Bechtold  E W Bushnell 《Child development》1976,47(3):860-863

Dynamic retinoscopy has suggested that near vision may be more acute than far vision during early infancy. To test this, acuity thresholds were determined by presenting square wave gratings in a preference paradigm to 1- and 2-month-old human infants at 4 viewing distances. Gratings were paired with unpatterned fields; direction of first fixation was the dependent measure. Infants exhibited the same acuity at each of the distances at which gratings were presented. The results were interpreted as compatible with the fact that considerable optical defocusing does not seriously affect a visual system, such as the infant's, that is sensitive only to low spatial frequencies.  相似文献   

Reflective and impulsive observing behavior     

E Siegelman 《Child development》1969,40(4):1213-1222

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Trial-by-trial analysis or averaging: implications for electromyographic models of rapid limb control     

Sherwood DE  Enebo BA 《Research quarterly for exercise and sport》2007,78(4):307-317

The control of human limb movement has been the focus of research for more than a century. A major issue to emerge from this work is the manner in which the central nervous system regulates electromyographic (EMG) activity to produce movements that differ in distance, velocity, and movement time. However the different methods of analysis often used to analyze EMG data could result in different kinematic-EMG relationships. In this study, participants performed an elbow flexion task to one of five distance goals (between 5 degrees and 50 degrees) using three movement speeds. EMG data from the right elbow flexors were compared using a trial-by-trial analysis and one based on averaged data. Averaging across trials underestimated biceps EMG amplitude at all movement distances and speeds compared to a trial-by-trial analysis. Averaging overestimated EMG burst duration compared to the trial-by-trial analysis. Peak agonist EMG amplitude was positively related to distance and inversely related to movement time. Agonist EMG duration was constant for movement distances less than 30 degrees but increased in the 50 degrees condition. The results support the view that peak EMG amplitude and duration can be controlled independently, but EMG duration changes only for longer distance movements when additional force is required.  相似文献   

Loving a Virtual Pet: Steps Toward the Technological Erosion of Emotion     

David W. Kritt 《Journal of American culture (Malden, Mass. : 2003)》2000,23(4):81-87

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Besprechungen     

K. Mertens  D. Kuhlmann  K. Roth  E. J. Hossner  H. Bernett  S. Güldenpfennig  J. Funke 《Sportwissenschaft》1990,20(2):200-218

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Equalizing connections for compound. Wound dynamos coupled in multiple     

E.R. Keller 《Journal of The Franklin Institute》1897,143(3):200-210

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Participant perceptions of exercise programs for overweight women   总被引：1，自引：0，他引：1  

L L Bain  T Wilson  E Chaikind 《Research quarterly for exercise and sport》1989,60(2):134-143

Eighteen women participated in a research project involving two phases: (a) an interview regarding weight history and exercise patterns, and (b) a series of exercise sessions followed by discussions of participants' reactions to them. The data were analyzed using inductive analysis techniques, and results of the analysis were discussed with participants for collaborative validation of the interpretation. Profiles of selected participants and themes that emerged are described. The participants varied in age and body size and had diverse backgrounds, interests, and abilities, but their shared experience of social disapproval based on body size was shown to affect their perceptions of exercise programs and their decisions about participation.  相似文献   

Computer-aided searching of bibliographic data bases: Online estimation of the value of information     

David R. Morehead  William B. Rouse 《Information processing & management》1985,21(5):387-399

The study presents and synthesizes the results of a series of five experiments on human information-seeking behavior in three different information-seeking environments. The first three experiments utilized a highly-controlled, simulated information-seeking task developed to study human search strategies in citation networks. Emphasis in the fourth and fifth experiments was placed on assessing the value of information for humans in realistic search environments. Subjects search on a topic of their own choice in a data base of fiction in Experiment Four and a data base of technical literature in Experiment Five. After summarizing the experimental results, a conceptual model of how humans value information is presented. The model is then used as a basis for a broad interpretation of the empirical results. Implications of both the empirical and modeling results are considered for the areas of information retrieval logic, system flexibility, retrieval methods, types of aiding, online estimation of information value, and computerizing versus computer-aiding.  相似文献   

Medical student, resident, and faculty use of a computerized literature searching system     

R J Markert  A J Parisi  H V Barnes  S Cohen  K Goldenberg  L E Mieczkowski  M Dunn  R M Siervogel 《Bulletin of the Medical Library Association》1989,77(2):133-138

The experiences of medical students, residents, and faculty with a computerized literature searching system were evaluated. Third-year medical students, internal medicine and family practice residents, and full-time and voluntary faculty at one medical school had the opportunity to use a full-text and bibliographic medical literature retrieval system free of charge for an eleven-month period. Subjects conducted nearly nine thousand literature searches over a period of 942 system hours. Questionnaire data showed that participants could learn to use and would use an electronic information system, felt capable of using the system, utilized the system for a variety of purposes and in a number of different ways, and viewed the system as a valuable tool in searching the medical literature. The results are discussed in the context of the educational needs of the four user-groups and medical education planning by institutions.  相似文献   

Letters     

P. K. W. DIGBY  JOHN E. FREUND 《Teaching Statistics》1985,7(3):90-90

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