Validating the multimedia activity recall for children and adolescents in a large New Zealand sample     

Ralph Maddison  Louise S. Foley  Tim S. Olds  Kate Ridley  Yannan Jiang 《Journal of sports sciences》2013,31(5):470-478

Abstract

The aim of the study was to validate the self-report Multimedia Activity Recall for Children and Adolescents (MARCA) against accelerometry for the assessment of physical activity in New Zealand children. Participants (n = 716, 10–18 years) recalled 3–4 days of activity using the MARCA and underwent a partially overlapping 7-day accelerometry protocol during a national survey. Spearman correlation coefficients (ρ) assessed the association between accelerometer-derived counts per minute and MARCA-derived physical activity level and time in locomotion. Both data sources estimated time spent in light and moderate–vigorous physical activity. Association and agreement between methods for light physical activity and moderate–vigorous physical activity was assessed using correlations and Bland–Altman plots respectively, and paired t-tests conducted. Accelerometer-derived activity counts were moderately correlated with both MARCA-derived physical activity level and locomotion (ρ = 0.38, P < 0.0001). The correlation between methods was –0.14 for light physical activity and 0.28 for moderate–vigorous physical activity (P < 0.0001). The MARCA overestimated moderate–vigorous physical activity compared with accelerometry (120 min, P < 0.0001), which increased as moderate–vigorous physical activity time increased. Some sex and ethnicity (Māori [indigenous] versus non-Māori) differences were observed. Overall, the MARCA indicated moderate validity for assessment of physical activity level, locomotion and moderate–vigorous physical activity and poor validity for assessment of light physical activity. This was comparable to other self-report tools. The MARCA has utility for future large-scale research.  相似文献   

A Kinetic Analysis of the Ground Leg During Sprint Running     

Ralph Mann  Paul Sprague 《Research quarterly for exercise and sport》2013,84(2):334-348

Abstract

Fifteen highly skilled sprinters were filmed while running at maximum velocity. The results were digitized and computer processed with interest focused on the muscle moments generated about the hip, knee, and ankle of the ground leg. Muscle activity about the hip consisted of extensor (concentric) dominance from foot descent, through foot strike, and into mid-support. Muscle dominance shifted to the hip flexors (eccentric) during mid-support and continued through takeoff. Muscle dominance at the knee demonstrated a pattern of flexor (eccentric, then concentric) dominance from foot descent through foot strike and into mid-support. Knee extensors (eccentric, then concentric) then achieved dominance through takeoff. During the later stages of takeoff, the dominance decreased or reversed briefly to flexor (eccentric) activity prior to a period of minimal activity following the toe-off position. From a period of minimal activity prior and subsequent to ground contact, the plantar flexors (eccentric, then concentric) of the foot were dominant throughout the ground phase. Qualitatively, the unexpected knee flexor dominance during foot strike was generated to limit the braking action created during this portion of ground contact. The unanticipated hip flexor dominance during takeoff served to rotate the upper body forward and into the approaching air phase. In addition, both of these actions allowed efficient use of the two-joint muscles of the leg during the critical phases of ground contact. Finally, the minimizing or reversing of the knee extensor dominance during the later stages of takeoff served to protect the joint from injury. Quantitatively, the magnitude of hip extensor/knee flexor activity during foot strike was significantly related (r = .70, p = .01) to the prior occurrences of related leg injury in the subjects.  相似文献   

Estimating Energy Expenditure With the RT3 Triaxial Accelerometer     

Ralph Maddison  Yannan Jiang  Stephen Vander Hoorn  Cliona Ni Mhurchu  Carlene M.M. Lawes  Anthony Rodgers 《Research quarterly for exercise and sport》2013,84(2):249-256

The RT3 is a relatively new triaxial accelerometer that has replaced the TriTrac. The aim of this study was to validate the RT3 against doubly labeled water (DLW) in a free-living, mixed weight sample of adults. Total energy expenditure (TEE) was measured over a 15-day period using DLW. Activity-related energy expenditure (AEE) was estimated by subtracting resting energy expenditure and thermic effect of feeding from TEE. The RT3 triaxial accelerometer was worn over 14 consecutive days. TEE and AEE were estimated using the RT3 proprietary equation. Thirty-six adults ages 18–56 years (56% women) with an average weight of 75.9 kg (SD = 14.8) completed all measurements. Compared to DLW, the RT3 underestimated TEE by 539 kJ (4%) and AEE by 485 kJ (15%) on average. The RT3 provided a relatively accurate assessment of free-living activity-related energy expenditure at the group level and generally underestimated total and activity-related energy expenditure compared to DLW.  相似文献   

The effect of subadditive pretraining on blocking: limits on generalization     

Wheeler DS  Beckers T  Miller RR 《Learning & behavior》2008,36(4):341-351

Recent evidence indicates that prior learning about a set of cues may determine how new cues are processed. If subjects are taught that two reliable predictors of an outcome do not summate when the cues are presented together (i.e., subadditive pretraining), the subjects will tend to show a less profound blocking effect when trained with different cues. Three experiments investigated the conditions necessary for subadditive pretraining to generalize to new cues. Experiment 1 demonstrated that subadditive pretraining is less effective in reducing blocking when it is experienced in a context other than that in which the blocking training is experienced. In Experiment 2, the effectiveness of subadditive pretraining waned with time. Experiment 3 showed that subadditive pretraining is more effective when the temporal characteristics of pretraining cues are similar to those of the cues used in blocking training. These results provide information concerning the conditions under which learning will generalize from one set of cues to another.  相似文献   

The inner world of school principals: Reflections on career life stages   总被引：2，自引：0，他引：2  

Lya Kremer-Hayon  Ralph Fessler 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1992,38(1):35-45

The study is aimed at disclosing the reflections of school principals on their careers and investigating whether these reflections point to any distinct career stages. Ten school principals were interviewed using the think aloud technique. This process was protocolled verbatim. The protocol content analysis yielded two developmental trends: From management to leadership, and from idealism to realism. These trends started in a distinct induction stage and continued to develop throughout a relatively long period of growth. Principals' career stages were compared with teachers' career stages that had been identified in the literature. In addition to the career stages that were identified two topics of references emerged: Environmental influences and time perspectives. Practical as well as theoretical implications of the findings are discussed.

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Zusammenfassung In diesem Artikel sollen Überlegungen der Schulleiter hinsichtlich ihrer Karriere näher beleuchtet, und es soll herausgefunden werden, ob diese Überlegungen auf bestimmte Stufen der Karriere hinweisen. Zehn Schulleiter wurden mit Hilfe der Technik des lauten Denkens interviewt. Dieser Prozess wurde wortgetreu protokolliert. Die Inhaltsanalyse des Protokolls ergab zwei Entwicklungstrends: von der Verwaltung zur Leitung und von Idealismus zu Realismus. Diese Trends begannen in einer bestimmten Einführungsphase und entwickelten sich während einer relativ langen Wachstumsphase weiter. Karrierestufen der Schulleiter wurden mit den in der Fachliteratur festgelegten Karriere stufen der Lehrer verglichen. Zusätzlich zu den identifizierten Karrierestufen ergaben sich zwei damit zusammenhängende Themen: Einflüsse durch die Umgebung und Zeitaspekte. Die praktischen und theoretischen Auswirkungen dieser Analyse werden erörtert.

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Résumé L'intention de cette étude est de révéler les réflexions de directeurs d'école sur leur carrière, et de déterminer si ces réflexions indiquent des étapes professionnelles discrètes. Un procès-verbal des entretiens avec dix directeurs fut rédigé, en utilisant une technique de penser à haute voix. L'analyse du contenu du procèsverbal montre deux tendances de développement: de la gestion vers le pilotage, et de l'idéalisme vers le réalisme. Ces tendances se manifestent à partir de l'étape distincte de l'admission et continuent à se développer durant une période de croissance relativement longue. Les chéminements professionnels des directeurs sont comparés avec ceux d'enseignants qui ont été identifiés dans la littérature. A part les étapes professionnelles ainsi déterminées, on a dégagé deux points de référence: les influences environnementales et les perspectives liées au temps. Les implications pratiques et théoriques des résultats sont discutées.

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Inflation of comparator stimuli following CS training     

Ralph R. Miller  Steve C. Hallam  Nicholas J. Grahame 《Learning & behavior》1990,18(4):434-443

Water-deprived rats served in seven conditioned lick suppression experiments designed to assess the effects on responding to a target CS of a series of unsignaled USs given in the training context following completion of CS training. Such treatment has been hypothesized to increase (inflate) the associative strength of the background cues from training (putatively, the CS’s comparator stimuli), thereby reducing responding to excitatory CSs and increasing the inhibitory potential of inhibitory CSs. Although posttraining extinction (deflation) of the CS’s comparator stimuli usually decreases inhibitory potential and increases excitatory potential of the target CS, posttraining inflation of the comparator stimuli had no effect on either excitatory responding to the target CS or summation test performance indicative of conditioned inhibition. This outcome was consistently obtained across a number of training, inflation, and test conditions selected to maximize sensitivity to any possible effects of comparator inflation. Implications of these null results for the comparator hypothesis of conditionedresponse generationare discussed.  相似文献   

Spontaneous recovery and ABC renewal from retroactive cue interference     

Miguez G  Cham HX  Miller RR 《Learning & behavior》2012,40(1):42-53

Two conditioned suppression experiments with rats were conducted to determine whether the spontaneous recovery and renewal that are commonly observed in retroactive outcome interference (e.g., extinction) also occur in retroactive cue interference. Experiment 1 showed that a long delay between Phase 2 (the interfering phase) and testing produces a recovery from the cue interference (i.e., the delay enhanced responding to the target cue trained in Phase 1), which is analogous to the spontaneous recovery effect observed in extinction and other retroactive outcome interference procedures. Experiment 2 showed that, when target and interfering cues are trained in separate contexts and testing occurs in a different but familiar context, a recovery from the cue interference is also observed (i.e., the context shift enhanced responding to the target), which is analogous to ABC renewal from extinction. The results are discussed in terms of the possibility that similar associative mechanisms underlie cue and outcome interference.  相似文献   

Performance factors in associative learning: Assessment of the sometimes competing retrieval model     

JE Witnauer  BM Wojick  CW Polack  RR Miller 《Learning & behavior》2012,40(3):347-366

Previous simulations revealed that the sometimes competing retrieval model (SOCR; Stout & Miller, Psychological Review, 114, 759-783, 2007), which assumes local error reduction, can explain many cue interaction phenomena that elude traditional associative theories based on total error reduction. Here, we applied SOCR to a new set of Pavlovian phenomena. Simulations used a single set of fixed parameters to simulate each basic effect (e.g., blocking) and, for specific experiments using different procedures, used fitted parameters discovered through hill climbing. In simulation 1, SOCR was successfully applied to basic acquisition, including the overtraining effect, which is context dependent. In simulation 2, we applied SOCR to basic extinction and renewal. SOCR anticipated these effects with both fixed parameters and best-fitting parameters, although the renewal effects were weaker than those observed in some experiments. In simulation 3a, feature-negative training was simulated, including the often observed transition from second-order conditioning to conditioned inhibition. In simulation 3b, SOCR predicted the observation that conditioned inhibition after feature-negative and differential conditioning depends on intertrial interval. In simulation 3c, SOCR successfully predicted failure of conditioned inhibition to extinguish with presentations of the inhibitor alone under most circumstances. In simulation 4, cue competition, including blocking (4a), recovery from relative validity (4b), and unblocking (4c), was simulated. In simulation 5, SOCR correctly predicted that inhibitors gain more behavioral control than do excitors when they are trained in compound. Simulation 6 demonstrated that SOCR explains the slower acquisition observed following CS-weak shock pairings.  相似文献   

The dual role of the context in postpeak performance decrements resulting from extended training     

Gonzalo P. Urcelay  James E. Witnauer  Ralph R. Miller 《Learning & behavior》2012,40(4):476-493

The context??s role in Pavlovian conditioning depends on the trial spacing during training, with massed trials revealing a function akin to that of discrete stimuli, and spaced trials revealing a modulatory function (Urcelay & Miller, Journal of Experimental Psychology. Animal Behavior Processes, 36, 268?C280, 2010). Here we examined the contextual determinants of a common but largely ignored effect: attenuated conditioned responding with extended reinforced training (i.e., a postpeak performance deficit [PPD]). Contextual sources of PPDs were investigated in four fear-conditioning experiments with rats. In Experiment 1, as the number of reinforced trials increased, conditioned responding decreased, even when testing occurred outside the training context. Experiment 2 revealed opposing influences of context on the PPD based on trial spacing, which interacted with whether testing occurred in the training context. This finding reconciles Experiment 1??s results with previous data (Bouton, Frohardt, Sunsay, Waddell, & Morris, Journal of Experimental Psychology. Animal Behavior Processes, 34, 223?C236, 2008). Experiment 3 suggested that extended training with these parameters did not lead to habituation to conditioned or unconditioned stimuli. In Experiment 4, few or many massed training trials were followed orthogonally by context extinction or no context extinction. After many pairings, context extinction reduced the PPD (i.e., enhanced responding), suggesting a competitive role of the context. These results, together with prior data suggesting that context modulates expressions of the PPD, are consistent with the view that contexts can play two distinctly different roles.  相似文献   

Ein Vorgehensmodell für die Multimedia-Entwicklung mit Autorensystemen     

Ralph Depke  Gregor Engels  Katharina Mehner  Stefan Sauer  Annika Wagner 《Informatik - Forschung und Entwicklung》1999,2(3):83-94

Multimedia-Anwendungen sind interaktive Softwaresysteme und verlangen als solche, mit softwaretechnischen Methoden erstellt zu werden. Sie werden heutzutage in der Regel mit Hilfe von Autorensystemen entwickelt, die eine Ad-hoc-Entwicklung auf Implementierungsniveau unterstützen. Hierdurch und wegen des Fehlens etablierter Vorgehensmodelle für die Multimedia-Softwareentwicklung reduziert sich der Multimedia-Entwicklungsproze? auf die Implementierungsphase. Dies führt zu den in der Softwaretechnik bekannten Problemen wie mangelnder Konzeption und fehlender Dokumentation. Wir stellen in diesem Beitrag ein Vorgehensmodell für die Entwicklung von Multimedia-Anwendungen vor, in dessen Mittelpunkt eine Analyse- und Entwurfsphase im Hinblick auf eine Implementierung der Multimedia-Anwendung mit einem Autorensystem stehen. Ausgehend von einem frameworkbasierten Analysemodell der Anwendung und einem Modell der Realisierungsm?glichkeiten mit einem konkreten Autorensystem wird systematisch ein Implementierungsmodell auf Instanzebene abgeleitet, das als Eingabe für das Autorensystem verwendet wird. Das postulierte Vorgehensmodell wird exemplarisch für das Autorensystem Director am Beispiel der Dom?ne multimedialer Lehr-/Lernanwendungen erl?utert.  相似文献