Influence of instruction on velocity and accuracy of overarm throwing

This study investigated the influence of instruction on the ball velocity and accuracy of a goal-directed overarm throw. 9 experienced Norwegian male team handball players executed a throwing task randomly seven times under 5 different instructions varying from emphasizing speed to accuracy. When instructions increasingly emphasized accuracy, velocity decreased. However, accuracy did not improve when subjects were instructed to focus on it. A possible explanation for this finding could lie in the specific subject group. The subjects were highly experienced team handball players with an average of 12 years in the sport. Thus, the accuracy they demonstrated at high velocity might actually be already extremely high and difficult to improve upon when reducing throwing velocity. Further, the velocity of throwing when instruction emphasized accuracy was approximately 85% of the maximal velocity, indicating that experienced team handball players are trained to throw accurately at relatively high velocity.     

The relation between problem categorization and problem solving among experts and novices

These investigations were conducted to examine the relationship between problem-solving ability and the criteria used to decide that two classical mechanics problems would be solved similarly. We began by comparing experts and novices on a similarity judgment task and found that the experts predominantly relied on the problems' deep structures in deciding on similarity of solution, although the presence of surface-feature similarity had a clear adverse effect on performance. The novices relied predominantly on surface features, but were capable of using the problems' deep structures under certain conditions. In a second experiment, we compared groups of novices, at the same level of experience, who tended to employ different types of reasoning in making similarity judgments. Compared to novices who relied predominantly on surface features, novices who made greater use of principles tended to categorize problems similarly to how experts categorized them, as well as score higher in problem solving. These results suggest that principles play a fundamental role in the organization of conceptual and procedural knowledge for good problem solvers at all levels.     

Diagnostic classification by experts and novices.

The present study examines differences between experts and novices in classifying symptoms and the effect of the nature of the task on classifying. The study involved three groups of subjects, two expert groups (n = 12, n = 10) and one novice group (n = 12). Thinking-aloud protocols were collected for two classification tasks: sorting of behavioural symptoms into predefined categories and intuitive clustering of behavioural symptoms. In a third task, experts and novices were asked to make typicality ratings of behavioural symptoms. The protocols were analyzed with respect to seven cognitive operations: (a) asking or giving information, (b) associating, (c) abstracting or labelling, (d) explaining, (e) neutral matching, (f) identifying, and (g) differentiating. Results showed an effect of experience and an effect of the task on the relative frequencies of these operations. No differences were found in typicality rating of experts versus novices. These contradictory findings are discussed in relation to Kolodner's model about the evolution of expertise.     

Categorization and representation of physics problems by experts and novices

The representation of physics problems in relation to the organization of physics knowledge is investigated in experts and novices. Four experiments examine (a) the existence of problem categories as a basis for representation; (b) differences in the categories used by experts and novices; (c) differences in the knowledge associated with the categories; and (d) features in the problems that contribute to problem categorization and representation. Results from sorting tasks and protocols reveal that experts and novices begin their problem representations with specifiably different problem categories, and completion of the representations depends on the knowledge associated with the categories. For, the experts initially abstract physics principles to approach and solve a problem representation, whereas novices base their representation and approaches on the problem's literal features.     

Formal and informal referent groups: an exploration of novices and experts in maternity services

Different social groups place varying emphasis on the importance of referent input. While referent groups are recognised as having a significant influence on purchase behaviour, attitude formation and information processing, the extent to which referent groups are a determinant in decision making is yet to be fully explored. Considering novice and expert users of the maternity services, this paper focuses on the significance of referent groups for women during the maternity process. This research produced interesting results, not least that novice and expert users, resident in lower ACORN areas are dependent on informal referent groups while novice users, resident in higher ACORN areas, are influenced by formal referent groups when making decisions regarding their care. Copyright © 2001 Henry Stewart Publications.     

Holistic processing of musical notation: Dissociating failures of selective attention in experts and novices

Holistic processing (i.e., the tendency to process objects as wholes) is associated with face perception and also with expertise individuating novel objects. Surprisingly, recent work also reveals holistic effects in novice observers. It is unclear whether the same mechanisms support holistic effects in experts and in novices. In the present study, we measured holistic processing of music sequences using a selective attention task in participants who vary in music-reading expertise. We found that holistic effects were strategic in novices but were relatively automatic in experts. Correlational analyses revealed that individual holistic effects were predicted by both individual music-reading ability and neural responses for musical notation in the right fusiform face area (rFFA), but in opposite directions for experts and novices, suggesting that holistic effects in the two groups may be of different natures. To characterize expert perception, it is important not only to measure the tendency to process objects as wholes, but also to test whether this effect is dependent on task constraints.     

Development of categorization and reasoning in the natural world: novices to experts,naive similarity to ecological knowledge

Two experiments investigate the role of similarity and causal-ecological knowledge in expert and novice categorization and reasoning. In Experiment 1, university undergraduates and commercial fishermen sorted marine creatures into groups; although there was substantial agreement, novices sorted largely on the basis of appearance, whereas experts often cited commercial, ecological, or behavioral factors, and systematically subdivided fish on the basis of ecological niche. In Experiment 2, experts and novices were asked to generalize a blank property or novel disease from a pair of marine creatures. Novices relied on similarity to guide generalizations. Experts used similarity to reason about blank properties but ecological relations to reason about diseases. Expertise appears to involve knowledge of multiple relations among entities and context-sensitive application of those relations.     

Tall is typical: Central tendency, ideal dimensions, and graded category structure among tree experts and novices

Many accounts of categorization equate goodness-of-example with central tendency for common taxonomic categories; the best examples of a category are average members--those that are most similar to most other category members. In the present study, we asked 24 tree experts and 20 novices to rate goodness-of-example for a sample of 48 trees and found (1) that the internal structure of the category tree differed between novices and experts and (2) that central tendency did not determine goodness-of-example ratings for either group. For novices, familiarity determined goodness-of-example ratings. For experts, the "ideal" dimensions of height and weediness, rather than average similarity to other trees, were the primary predictors of goodness-of-example ratings for experts. The best examples of tree were not species of average height, but of extreme height. The worst examples were the weediest trees. We also found systematic differences in predictors of goodness-of-example as a function of type of expertise. We argue that the internal structure of taxonomic categories can be shaped by goal-related experience and is not necessarily a reflection of the attributional structure of the environment. Implications for models of category structure and category learning are discussed.     

Lateral asymmetries in the development of the overarm throw

Lateral asymmetries of manual, pedal, and ocular preferences, and motor asymmetry in the performance of the forceful overarm throw were analyzed in 71 children aged 4 to 10 years old. Performance with each side of the body was assessed on the basis of qualitative analysis, as proposed by M. A. Roberton and L. Halverson (1984) for identification of developmental stages by components of the task. Lateral preference was indicated by the frequency the children used the right or the left side of their body to carry out different manual, pedal, and ocular tasks. The overarm throw movement pattern was developed with both sides of the body but at different levels. Development of the nondominant side lagged behind that of the dominant side at all ages; a significant asymmetry in performance detected in the 4-year-olds was stable up to the age of 10 years. Indices of asymmetry for lateral preference and performance were found to be specific because no consistent correlations were observed among them throughout the age periods studied. Those results show the multidimensional character of human laterality and imply a property of motor development that prevents asymmetry of performance from increasing because of unilateral practice.     

Differences between experts and non-experts in photographic perception and assessment

How professional skills and schemata do affect cognition, evaluative dimensions and aesthetic perception of pictures? And what about the effect of social elements like a smiling or serious subject pictured? The present study investigates the differences between Experts (photo professionals) and inexperienced individuals in perception and evaluation of photographs. Furthermore, it approaches the influence of different facial expressions (Reis et al. in Euro J Soc Psychol 20(3):259-267, 1990). People with well-developed schemes in photography should evaluate pictures through assessment, while inexperienced people should evaluate pictures through appraisal? N = 118, 60 Experts and 58 inexperienced people were asked to evaluate a set of stimulus pictures throughout: (a) 'The Circumplex Model of Affect' (PAQs) to measure 4 affective dimensions; and (b) a Semantic Differential made of 9 couples of bipolar adjectives to measure 2 evaluative dimensions (Aesthetics and Distinctive Features). Results partially confirmed the hypotheses: Experts differ significantly from Non-experts in picture evaluations. Smile arouses more positive evaluations, but only in the inexperienced group. No subject position effects were found. These results are in concordance with previous research about Expert and Non-expert evaluation, and they open new questions about facial expressions studies.     

A testosterone-mediated trade-off between parental and sexual effort in male mongolian gerbils (Meriones unguiculatus)

Effects of testosterone (T) on parental behavior of male Mongolian gerbils (Meriones unguiculatus) were examined. After undergoing gonadectomy, castrated males were implanted with empty capsules or capsules containing T; sham-operated males were implanted with empty Silastic capsules. Subsequently, each male was paired with a pregnant female, and after delivery, families were observed 15 min/day for 20 days. Gonadectomized males without T spent more time in contact with, huddling over, and licking pups than did either sham-operated males or gonadectomized males with T. When given a choice between nest sites and displaced pups, females and males with low T preferred pups, whereas intact males and castrated males with T preferred nest sites. The findings are consistent with E. D. Ketterson and V. Nolan's (1994) hypothesis implicating T in mediating trade-offs between parental and sexual effort.     

The trade-off between accuracy and precision in latent variable models of mediation processes

Social psychologists place high importance on understanding mechanisms and frequently employ mediation analyses to shed light on the process underlying an effect. Such analyses can be conducted with observed variables (e.g., a typical regression approach) or latent variables (e.g., a structural equation modeling approach), and choosing between these methods can be a more complex and consequential decision than researchers often realize. The present article adds to the literature on mediation by examining the relative trade-off between accuracy and precision in latent versus observed variable modeling. Whereas past work has shown that latent variable models tend to produce more accurate estimates, we demonstrate that this increase in accuracy comes at the cost of increased standard errors and reduced power, and examine this relative trade-off both theoretically and empirically in a typical 3-variable mediation model across varying levels of effect size and reliability. We discuss implications for social psychologists seeking to uncover mediating variables and provide 3 practical recommendations for maximizing both accuracy and precision in mediation analyses.     

Individual differences and segment interactions in throwing

Arm segment velocities of 12 athletes throwing three differently weighted balls were analyzed by three-mode principal component analysis. Individual differences were characterized in terms of the combined influences of the phases of the throwing motion and the arm segment velocity relationships established in those phases. Using three individual differences components, three velocity measures components and four time phase components, 75% of the variance was described. The arm segment velocity relationships were described by two main components identified as directional velocity and proximal versus distal velocity. The time periods components distinguished between relationships among the arm segment velocities that occur in the windup versus those of the release phase. Three individual differences components are identified and appeared to be related to a general throwing style, the influence of skill level on technique, and the differential effect of the varying ball weights, respectively. Each athlete's throws are weighted combinations of these three components. The timing of segment involvement is investigated and the results indicate sequential patterns from proximal to distal as the throw unfolds. However, the results also suggest that different principles may apply to different throwers and that the summation of speed principle should not be applied universally to explain segment motion and interaction.     

Bias and runs in dice throwing and recording: A few million throws

An experimenter threw individually 219 different dice of four different brands and recorded even and odd outcomes for one block of 20,000 trials for each die—4,380,000 throws in all. The resulting data on runs offer a basis for comparing the observed properties of such a physical randomizing process with theory and with simulations based on pseudo-random numbers and RAND Corporation random numbers. Although generally the results are close to those forecast by theory, some notable exceptions raise questions about the surprise value that should be associated with occurrences two standard deviations from the mean. These data suggest that the usual significance level may well actually be running from 7 to 15 percent instead of the theoretical 5 percent.The data base is the largest of its kind. A set generated by one brand of dice contains 2,000,000 bits and is the first handmade empirical data of such size to fail to show a significant departure from ideal theory in either location or scale.The analysis was facilitated by a National Science Foundation grant GS-341 and and its continuation GS-2044X. It forms part of a larger study of data analysis.Mr. Longcor is from Waukegan, Illinois; the other authors are from Harvard University. Dr. Iversen has moved to the University of Michigan.     

佛教与婆罗门教善恶观念比较

佛教与婆罗门教是古代印度的两个主要宗教派别。它们的善恶观念是各自理论体系中的重要组成部分。两教的此类观念虽然有明显不同,但都与古代印度圣典吠陀和奥义书有渊源关系。佛教和婆罗门教各自的善恶观念都有不同层次的划分。在后来的发展中,两教的善恶观念有很大的趋同性,它们相互影响,彼此吸收对方思想。两教中的一些基本层次的善恶观念的内容有大量是相同的,较高层次的善恶观念虽有不同,但同样强调智慧解脱。这方面的思想对古代印度系统宗教哲学的形成起了促进作用,在世界文化发展史上占有重要地位。     

Navigation assistance: a trade-off between wayfinding support and configural learning support

Current GPS-based mobile navigation assistance systems support wayfinding, but they do not support learning about the spatial configuration of an environment. The present study examined effects of visual presentation modes for navigation assistance on wayfinding accuracy, route learning, and configural learning. Participants (high-school students) visited a university campus for the first time and took a predefined assisted tour. In Experiment 1 (n = 84, 42 females), a presentation mode showing wayfinding information from eye-level was contrasted with presentation modes showing wayfinding information included in views that provided comprehensive configural information. In Experiment 2 (n = 48, 24 females), wayfinding information was included in map fragments. A presentation mode which always showed north on top of the device was compared with a mode which rotated according to the orientation of the user. Wayfinding accuracy (deviations from the route), route learning, and configural learning (direction estimates, sketch maps) were assessed. Results indicated a trade-off between wayfinding and configural learning: Presentation modes providing comprehensive configural information supported the acquisition of configural knowledge at the cost of accurate wayfinding. The route presentation mode supported wayfinding at the cost of configural knowledge acquisition. Both presentation modes based on map fragments supported wayfinding. Individual differences in visual-spatial working memory capacity explained a considerable portion of the variance in wayfinding accuracy, route learning, and configural learning. It is concluded that learning about an unknown environment during assisted navigation is based on the integration of spatial information from multiple sources and can be supported by appropriate visualization.