Effects of different acquisition procedures on response variability     

Patricia D. Stokes  Francis Mechner  Peter D. Balsam 《Learning & behavior》1999,27(1):28-41

In three experiments with college students, the effects of different acquisition procedures on response variability were studied. The computer keypressing task involved learning a sequence with a minimum number of presses on a subset of the keyboard. Procedures differed in type of training and in the number, size, and sequence of training steps. Experiment 1 showed that instructions and shaping in three steps generated less variability in the number of responses made in each keypress sequence than shaping in six steps. Subsequent experiments showed that a large increase in the response requirement early in shaping increased variability. Postacquisition variability remained unchanged in the number of responses per sequence—the aspect of responding on which reinforcement was contingent—but declined in location and timing of keypressing. The results are discussed in terms of the implicit reinforcement of variability and how the acquisition of qualitatively different response strategies could influence variability.  相似文献   

Document clustering of scientific texts using citation contexts   总被引：3，自引：0，他引：3  

Bader Aljaber  Nicola Stokes  James Bailey  Jian Pei 《Information Retrieval》2010,13(2):101-131

Document clustering has many important applications in the area of data mining and information retrieval. Many existing document clustering techniques use the “bag-of-words” model to represent the content of a document. However, this representation is only effective for grouping related documents when these documents share a large proportion of lexically equivalent terms. In other words, instances of synonymy between related documents are ignored, which can reduce the effectiveness of applications using a standard full-text document representation. To address this problem, we present a new approach for clustering scientific documents, based on the utilization of citation contexts. A citation context is essentially the text surrounding the reference markers used to refer to other scientific works. We hypothesize that citation contexts will provide relevant synonymous and related vocabulary which will help increase the effectiveness of the bag-of-words representation. In this paper, we investigate the power of these citation-specific word features, and compare them with the original document’s textual representation in a document clustering task on two collections of labeled scientific journal papers from two distinct domains: High Energy Physics and Genomics. We also compare these text-based clustering techniques with a link-based clustering algorithm which determines the similarity between documents based on the number of co-citations, that is in-links represented by citing documents and out-links represented by cited documents. Our experimental results indicate that the use of citation contexts, when combined with the vocabulary in the full-text of the document, is a promising alternative means of capturing critical topics covered by journal articles. More specifically, this document representation strategy when used by the clustering algorithm investigated in this paper, outperforms both the full-text clustering approach and the link-based clustering technique on both scientific journal datasets.  相似文献   

Initial hydration status, fluid balance, and psychological affect during recreational exercise in adults     

Peacock OJ  Stokes K  Thompson D 《Journal of sports sciences》2011,29(9):897-904

There is little information on the impact of hydration status on the psychological response to exercise despite potential implications for adherence to an exercise programme and for overall health and fitness. We investigated initial hydration status, fluid balance, and psychological responses associated with a typical recreational exercise session in healthy adults. Fifty-two participants performed a freely chosen gymnasium-based exercise session at a fitness centre, with ad libitum access to fluids. Urine samples were collected on arrival for analysis of osmolality. Sweat loss was estimated from the change in body mass after correction for fluid intake and urinary losses. Subjective psychological ratings were recorded before and after exercise. Pre-exercise urine osmolality was above 900 mOsmol · kg(-1) (used as a threshold for hypohydration) in 37% of participants. Fluid intake during exercise was 390 ± 298 mL, while estimated sweat loss was 794 ± 391 mL. The percentage change from pre-exercise body mass was -0.62 ± 0.20%. Physically active adults who arrived to take part in exercise hypohydrated reported more negative changes in psychological affect in response to their subsequent freely chosen recreational exercise session than those classified as euhydrated prior to exercise (-0.2 ± 0.7 vs. 0.8 ± 0.7; P < 0.005).  相似文献   

Hanging in with kids in tough times: engagement in contexts of educational disadvantage in the relational school     

Helen Stokes  Malcolm Turnbull 《教育政策杂志》2013,28(6):857-858

  相似文献   

Doing the plastic fantastic: ‘artificial’ adventure and older adult climbers     

Mark Hickman  Peter Stokes  Colin Beard  Allison Inkster 《Journal of Adventure Education & Outdoor Learning》2019,19(2):172-182

ABSTRACT

The aim of this article is to determine the perceptions and experiences of climbing at artificial climbing walls (ACWs) as undertaken by a cohort of ‘young-old’ people (approximately 65–75 years). The engagement of older people in outdoor activities and adventure is an evolving topic; however, as part of this development, little has been written on the use of ACWs. Methodologically, the research employed in-depth semi-structured focus groups and interviews with a purposive convenience sample of six recreational climbers, subsequently expanded to ten through snowball technique. Both sexes were equally represented. Manual thematic analysis identified two key motifs: ACWs and the notion of adventure, and ACWs and the potential for learning. The findings point at what constitutes ‘real’ adventure for this group of older adults; the shifting nature of ‘old age’; the significance of self-awareness; and the role of reflexivity and physical activity in the construction of a ‘successful’ old age.  相似文献   

Pedagogies of Possibility     

William T. Stokes 《Review of Education, Pedagogy & Cultural Studies》2013,35(3):327-341

  相似文献   

Short‐term policy support for long‐term school change: a dilemma for reform‐minded practitioners     

Laura Stokes 《教育政策杂志》2013,28(5):371-384

This paper questions the ability of a reform policy of five years’ duration to create the conditions necessary for practitioners to sustain change. California's school restructuring initiative challenged schools to transfer authority to teachers and to demonstrate that every student could succeed in learning. Analysis of this progressive policy is based upon the ‘best‐case’ experiences of an exemplary elementary school staff. After five years, the teachers are just developing the ability to confront the volatile issues of race and social class that surfaced in their inquiries into persistent disparities in student achievement. Using theories from institutional analysis of organizations, the paper argues that withdrawal of policy support means weakening of the regulative, cognitive and normative legitimacy for the goals and processes of change. Fixed‐term policies which invite radical reform thus leave schools vulnerable to the tradition‐reinforcing institutions that remain after the initiative has ended.  相似文献   

Science and rugby union     

Mellalieu S  Trewartha G  Stokes K 《Journal of sports sciences》2008,26(8):791-794

  相似文献   

Federal publications cutbacks: Implications for libraries     

Judith E. Stokes 《Government Information Quarterly》1984,1(1):49-57

Since President Reagan's April 1981 moratorium on new government publications and audiovisual products, the restrictions this administration has imposed on executive agency data collection and publishing activities have provoked considerable controversy both in Congress and in the media. This article attempts to characterize the impact on libraries of the restrictions. An examination of the Office of Management and Budget's List of Government Publications Terminated and Consolidated by Agency as compared with depository distribution patterns, agency publication policies established by the President's Task Force on Management Reform, and reductions in data collection activities directed by the Office of Information and Regulatory Affairs are reported. A pattern of neglect in federal information collection and dissemination is shown to increase libraries' dependence on private sector publishing of government information, and to reduce the availability and comparability of certain federal statistical documentation collected by libraries.  相似文献   

Corporate author authority list: Springfield,Virginia: National Technical Information Service, 1983, 1446 pages. $175.00. NTIS Order Number: PB83-156034     

Judith E. Stokes 《Government Information Quarterly》1985,2(1):118

  相似文献