Establishing a Kinetic Assessment of Reactive Strength

The reactive strength index (RSI) is the current “gold standard” assessment of reactive strength. Traditional measures of reactive strength, including the RSI, are not strength-based and are founded using untested theoretical assumptions. The purpose of this study was to develop two versions of a kinetic-based paradigm of reactive strength (New and AdjNew) and compare them against the Coefficient of Reactivity (CoR) and the RSI. Twenty one NCAA Division I basketball players and 59 young adults from the general population performed two reactive strength protocols: Progressive drop jumping and repetitive countermovement jumping. For every jump, the CoR, RSI, New, and AdjNew were computed. Measure agreeability was assessed using the Bland-Altman approach and linear regressions. Analyses of variance (ANOVA) assessed the effect of sport participation, age, and sex on the four measures of reactive strength. Lastly, effects of self-reported physical activity levels were assessed using stepwise linear regressions. The strongest association was observed between AdjNew and the RSI (R2= 0.636). All NCAA \u3e young adults). The RSI, New, and AdjNew were sensitive to effects of sex and sport participation in repetitive countermovement jumping (males \u3e females; NCAA \u3e young adults). There are theoretical issues with the computation and implementation of the CoR and RSI. For example, the CoR and RSI are non-strength based measures that attempt to measure a strength construct. Further, the CoR, RSI, and New make the theoretical assumption that no biological variability exists in human movement. The AdjNew paradigm addresses and solves the theoretical issues with the CoR, RSI, and New. Therefore it may be argued that the AdjNew paradigm improves the theoretical validity of reactive strength assessment and is preferred over the RSI. The AdjNew is kinetic based, comprised of only measured component variables, and is not founded in assumptions of theory. This dissertation provides objective theoretical evidence to suggest that the AdjNew paradigm is an improvement over the RSI as a model of reactive strength

Is conditioning a useful framework for understanding the development and treatment of phobias?

Despite the prevalence of therapeutic interventions based on conditioning models of fear acquisition, conditioning has been seen by many as a poor explanation of how fears develop: partly because research on conditioning has become less mainstream and models of teaming have become increasingly more complex. This article reviews some of what is now known about conditioning/associative teaming and describes how these findings account for some early criticisms of conditioning models of fear acquisition. It also describes how pathways to fear such as vicarious teaming and fear information can be conceptualised as forms of associative teaming that obey the same teaming rules. Some popular models of conditioning are then described with a view to highlighting the important components in teaming. Finally, suggestions are made about how what we know about conditioning can be applied to improve therapeutic interventions and prevention programs for child anxiety. (c) 2006 Elsevier Ltd. All rights reserved

Information driven self-organization of complex robotic behaviors

Information theory is a powerful tool to express principles to drive autonomous systems because it is domain invariant and allows for an intuitive interpretation. This paper studies the use of the predictive information (PI), also called excess entropy or effective measure complexity, of the sensorimotor process as a driving force to generate behavior. We study nonlinear and nonstationary systems and introduce the time-local predicting information (TiPI) which allows us to derive exact results together with explicit update rules for the parameters of the controller in the dynamical systems framework. In this way the information principle, formulated at the level of behavior, is translated to the dynamics of the synapses. We underpin our results with a number of case studies with high-dimensional robotic systems. We show the spontaneous cooperativity in a complex physical system with decentralized control. Moreover, a jointly controlled humanoid robot develops a high behavioral variety depending on its physics and the environment it is dynamically embedded into. The behavior can be decomposed into a succession of low-dimensional modes that increasingly explore the behavior space. This is a promising way to avoid the curse of dimensionality which hinders learning systems to scale well.Comment: 29 pages, 12 figure

Seeing by exploring

The classical notion of how things are seen is that perception is passive, that the eyes are windows, and in floods reality. Physiological work of the 19th century cast doubt on this view that perception is passive acceptance of reality. Perception is not at the present time a popular topic for philosophers. This must be partly because scientific accounts of perception have now gone a long way away from appearances. They depend on physiological and psycho-physical experiments which require technical investigation and do not fall within traditional concepts of philosophy. Theories of visual perception are examined, both from a physical and psycho-physical standpoint

Development of data base software to facilitate instrument selection in the adapted physical education assessment process

The purpose of the study discussed in this thesis was to compile adapted physical education assessment instrument information into a matrix which matches test categories with parameters appropriate to the selection of a specific assessment instrument. From this matrix, a data base software program was developed. Use of the data base software program and thesis will enable the adapted physical educator to select a proper assessment instrument

CreaTable Content and Tangible Interaction in Aphasia

Multimedia digital content (combining pictures, text and music) is ubiquitous. The process of creating such content using existing tools typically requires complex, language-laden interactions which pose a challenge for users with aphasia (a language impairment following brain injury). Tangible interactions offer a potential means to address this challenge, however, there has been little work exploring their potential for this purpose. In this paper, we present CreaTable – a platform that enables us to explore tangible interaction as a means of supporting digital content creation for people with aphasia. We report details of the co-design of CreaTable and findings from a digital creativity workshop. Workshop findings indicated that CreaTable enabled people with aphasia to create something they would not otherwise have been able to. We report how users’ aphasia profiles affected their experience, describe tensions in collaborative content creation and provide insight into more accessible content creation using tangibles

Online Tracking of the Contents of Conscious Perception Using Real-Time fMRI

Perception is an active process that interprets and structures the stimulus input based on assumptions about its possible causes. We use real-time functional magnetic resonance imaging (rtfMRI) to investigate a particularly powerful demonstration of dynamic object integration in which the same physical stimulus intermittently elicits categorically different conscious object percepts. In this study, we simulated an outline object that is moving behind a narrow slit. With such displays, the physically identical stimulus can elicit categorically different percepts that either correspond closely to the physical stimulus (vertically moving line segments) or represent a hypothesis about the underlying cause of the physical stimulus (a horizontally moving object that is partly occluded). In the latter case, the brain must construct an object from the input sequence. Combining rtfMRI with machine learning techniques we show that it is possible to determine online the momentary state of a subject’s conscious percept from time resolved BOLD-activity. In addition, we found that feedback about the currently decoded percept increased the decoding rates compared to prior fMRI recordings of the same stimulus without feedback presentation. The analysis of the trained classifier revealed a brain network that discriminates contents of conscious perception with antagonistic interactions between early sensory areas that represent physical stimulus properties and higher-tier brain areas. During integrated object percepts, brain activity decreases in early sensory areas and increases in higher-tier areas. We conclude that it is possible to use BOLD responses to reliably track the contents of conscious visual perception with a relatively high temporal resolution. We suggest that our approach can also be used to investigate the neural basis of auditory object formation and discuss the results in the context of predictive coding theory

Do Actions Speak Louder Than Knowledge? Action Manipulation, Parent-Child Discourse And Children’S Mental State Understanding In Pretense

In the current study children 3-5 years of age (N = 75) participated in a mental state task to investigate the effect of action saliency on young children\u27s appreciation of mental states during pretend play activities. They also engaged in a parent-child interaction period, including storybook reading and pretend play activities, in order to examine the relation between mental state term utterances and performance on the mental state task. Two actors appeared side-by-side on a television screen, either in motion or as static images; one actor had knowledge of the animal he was pretending to be; the other actor did not have the same knowledge. The actors\u27 behaviors were identical and related to the behavior of the animal, identical and unrelated, or the knowledgeable actor behaved contradictory to the animal\u27s behavior while the unknowledgeable actor behaved appropriately for that animal. Children were asked to select the actor who was pretending to be the animal. Children selected the appropriate knowledgeable actor significantly more often than a non-knowledgeable actor. Older children performed better than younger children. Children\u27s performance was unaffected by whether actors were shown in motion as compared to simply a static image. Children performed most successfully on trials where actors were both engaged in behaviors unrelated to the animal\u27s behavior and poorest when the actor\u27s behavior was contradictory to his knowledge. The mental state utterances of parents and children were correlated with the children\u27s performance on the mental state task. Hierarchical regression analyses revealed parent\u27s mental state utterances used during the parent-child interactions - specifically cognitive terms and modulations of assertion - were predictive of their children\u27s performance on the mental state task. The current study\u27s results support an understanding of the mind in pretend play activities by some children younger than five years of age and this understanding may be influenced by their parents\u27 use of mental state language. Children who do not do well in appreciating that the mind is essential during pretense activities may have difficulty inhibiting responding to action, thus interfering with their ability to maintain focus on the mental state of the pretender

An Analysis of Eye Movements With Helmet Mounted Displays

Helmet or Head-Mounted Displays (HMD) applications have expanded to include a range from advanced military cockpits to consumer glasses. However, users have documented loss of legibility while undergoing vibration. Recent research indicates that undesirable eye movement is related to the vibration frequency a user experiences. In vibrating environments, two competing eye reflexes likely contribute to eye movements. The Vestibulo-ocular Reflex responds to motion sensed in the otoliths while the pursuit reflex is driven by the visual system to maintain the desired image on the fovea. This study attempts to isolate undesirable eye motions that occur while using a HMD by participants completing simple visual tasks while experiencing vertical vibration at frequencies between 0 and 10 Hz. Data collected on participants\u27 head and helmet movements, vibration frequency, acceleration level, and visual task are compared to eye movements to develop a method to understand the source of the unintended eye movements. Through the use of Electro- Oculography (EOG) eye movements were largest when a 4 Hz vibration frequency was applied, and are significantly different from the EOG signal at 2, 8 and 10 Hz. Stepwise regression indicated that head pitch acceleration and helmet slippage pitch acceleration were correlated with EOG values