A Test of Order-Constrained Hypotheses for Circular Data With Applications to Human Movement Science

Researchers studying the movements of the human body often encounter data measured in angles (e.g., angular displacements of joints). The evaluation of these circular data requires special statistical methods. The authors introduce a new test for the analysis of order-constrained hypotheses for circular data. Through this test, researchers can evaluate their expectations regarding the outcome of an experiment directly by representing their ideas in the form of a hypothesis containing inequality constraints. The resulting data analysis is generally more powerful than one using standard null hypothesis testing. Two examples of circular data from human movement science are presented to illustrate the use of the test. Results from a simulation study show that the test performs well.     

Exploring the Limits of Peripheral Vision for the Control of Movement

The role played by peripheral visual information in the control of aiming movements is not fully understood, as is indicated by the conflicting results reported in the literature. In the present study, the authors tested and confirmed the hypothesis that the source of the conflict lies in the portion of the visual peripheral field that has been under scrutiny in the different studies. Participants (N = 60) moved a computer mouse from a fixed starting position to 1 of 3 targets under varied vision conditions. The portion of the peripheral visual field that best ensured directional accuracy of a sweeping movement was found to be located between 20° and 10° of visual angle, whereas the area found to favor directional accuracy of an aiming movement comprised 30° through 10° of visual angle.     

Testing Hypotheses Distilled from Four Models of the Effects of Health-Related Social Control

This study distilled and tested hypotheses derived from four models of the effects of social control on affect and health behavior among 401 college students involved in heterosexual dating relationships. Each model received at least some support. Consistent with the dual effects model, social control strategies predicted both health behavior change and negative affect. In accord with the domain-specific model, positive social control was related to positive affect and negative social control was related to negative affect. In partial support of the mediational model, positive social control exerted both a direct and an indirect effect via positive affect on health behavior change and negative social control exerted both a direct and an indirect effect via negative affect on hiding unhealthy behavior. As predicted by the contextual model, quality of dating relationship moderated the influence of positive and negative social control on hiding unhealthy behavior.     

A Linked Muscular Activation Model for Movement Generation and Control

A new model for movement control is presented which incorporates characteristics of impulse-variability and mass-spring models. Movements in the model were controlled with phasic torque impulses in agonist and antagonist muscles and a tonic agonist torque.

Characteristics of the phasic agonist and antagonist torque profiles were based on observed properties of movement-related EMGs and muscle isometric torques. Variability of the phasic impulses depended on impulse magnitude as in impulse-variability models. The model therefore predicted a speed-accuracy tradeoff for limb movement. The time of onset and magnitude of the antagonist torque depended on the magnitude of the preceding agonist torque as indicated in studies of movement-related EMGs. This led to the new concept of linkage between the agonist and antagonist muscle forces which was shown to be important for reducing variability of fast movements. Progressive development of linkage during practice could explain the previous findings of decreased movement variability with practice coupled with increased variability of movement-related EMGs.

It was concluded that an inherently variable motor system deals with the variability associated with generation of large muscle forces by linking the forces produced by opposing muscles. In this way, variability in net joint torques and in movements can be decreased without the need for the nervous system to closely regulate the individual torques.     

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55 degrees /s) than those usually used in studies that had proved its existence (over 110 degrees /s) was delineated. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.     

Model Predictive Impedance Control: A Model for Joint Movement

Impedance control has been suggested as the strategy employed by the central nervous system to control human postures and movements. A realization of this strategy is presented that uses a model predictive control algorithm as a higher motor controller. External disturbances are explicitly included in the model. The combination of 3 key factors-joint impedance control, model predictive controller, and external disturbance input-forms the basis for the generality of this model. The model was applied to 3 different types of joint movements: a tracking movement with an unpredicted disturbance, a rhythmic movement, and an unstable biped model of human walking. Computer simulation results showed excellent performance of the model in all 3 cases for optimal values of active joint impedances and an exact match between the musculoskeletal system and the model internal to the model predictive controller. The controller was also able to maintain acceptable performance in the presence of a 25% mismatch between the musculoskeletal system and its internal model.     

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55°/s) than those usually used in studies that had proved its existence (over 110°/s) was determined. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.     

Seeking Confirmation Is Rational for Deterministic Hypotheses

The tendency to test outcomes that are predicted by our current theory (the confirmation bias) is one of the best‐known biases of human decision making. We prove that the confirmation bias is an optimal strategy for testing hypotheses when those hypotheses are deterministic, each making a single prediction about the next event in a sequence. Our proof applies for two normative standards commonly used for evaluating hypothesis testing: maximizing expected information gain and maximizing the probability of falsifying the current hypothesis. This analysis rests on two assumptions: (a) that people predict the next event in a sequence in a way that is consistent with Bayesian inference; and (b) when testing hypotheses, people test the hypothesis to which they assign highest posterior probability. We present four behavioral experiments that support these assumptions, showing that a simple Bayesian model can capture people's predictions about numerical sequences (Experiments 1 and 2), and that we can alter the hypotheses that people choose to test by manipulating the prior probability of those hypotheses (Experiments 3 and 4).     

Monocular and Binocular Vision in the Control of Goal-Directed Movement

In the present research the authors examined the time course of binocular integration in goal-directed aiming and grasping. With liquid-crystal goggles, the authors manipulated vision independently to the right and left eyes of 10 students during movement preparation and movement execution. Contrary to earlier findings reported in catching experiments (I. Olivier, D. J. Weeks, K. L. Ricker, J. Lyons, & D. Elliott, 1998), neither a temporal nor a spatial binocular advantage was obtained in 1 grasping and 2 aiming studies. That result suggests that, at least in some circumstances, monocular vision is sufficient for the precise control of limb movements. In a final aiming experiment involving 3-dimen- sional spatial variability and no trial-to-trial visual feedback about performance, binocular vision was associated with greater spatial accuracy. Binocular superiority appeared to be most pronounced when participants were unable to adjust their limb control strategy or procedure on the basis of terminal feedback about performance.     

A Note on the Speed-Amplitude Function in Movement Control

An experiment is reported that documents the maximum average speed-amplitude relationship across the full range of motion for elbow flexion. Minimum movement time increased as a negative exponential within the movement range up to 94-97% of the maximum range of motion. At this point a discontinuity occurred with movement time increasing at an increasing rate probably due to anatomical and morphological constraints. These results suggest that the maximum average velocity-amplitude boundary to the movement speed-accuracy relationship is curvilinear. Kinematic analysis of the movements as a function of range of motion suggests that a simple pulse-step model of movement control cannot account for the present findings.     

Movement Control in a Reciprocal Tapping Task

A cross-sectional approach was used to replicate and examine developmental flexibility in eye-hand relationships during alternate tapping performance. A group of 68 male subjects, 34 younger (mean 75.6 months) and 34 older (mean 128.9 months) practiced 12 5-sec trials of alternate tapping in one of three accuracy conditions. Trials 2 and 11 were filmed to determine the eye movement index (EMI), a fraction relating eye movements (numerator) to alternate taps (denominator). Fractional EMI values close to 1 were labelled discontinuity and values closer to 0 (1/N) continuity. Accuracy variation tested the flexibility of EMI. for developmental change, revealing that EMIs for older subjects were more continuous than for younger subjects at trial 11, but not at trial 2. Level of EMI was related to age and condition, while change in EMI due to practice was related to age. The data showed EMI strategy flexibility increased with age, and that faster tapping was afforded by less direct visual monitoring of the hand.     

酒精对视觉加工和眼动行为控制的影响(中文)

Although moderate alcohol consumption is known to degrade performance in a variety of tasks, the exact nature and extent of such impairments is not well understood. We examined alcohol effects on different levels of visual processing and oculomotor control. On the lowest level(automatic), reflexive responses were tested using the prosaccade task. The‘automated’level, incorporating routine behavior based on implicit learning, was studied using the double step paradigm, while the highest level, representing voluntary control, was examined with antisaccade and memory guided tasks. In addition, sentence reading was included as a prototypical complex task with high ecological validity. Participant′s baseline performance was compared to alcohol conditions with intoxication levels around 70mg% of breath alcohol concentration. Functioning on the automatic level was intact, except for a substantial slowing in saccade latencies. On the automated level, deficits in the ability to adaptively reprogram saccades on the basis of new information were found. Impairments in voluntary control were apparent in hypermetric saccade amplitudes whenever a reprogramming of the initial saccade target was necessary. There was also a small but significant detrimental effect on visuospatial short term memory. Somewhat surprisingly, no alcohol related deficits emerged with regard to inhibitory functions. ‘Reading under the influence’resulted in substantially prolonged fixation durations with only a modest increase in total viewing time per word. A trade-off between increased duration and decreased number of fixations pointed to the possibility that the extra time available under alcohol can be used for linguistic processing, which in itself did not appear to be impaired. This idea is supported by the fact that there was no interaction between alcohol and word frequency. Contrary to expectation, the processing of parafoveal information during reading was not impeded. Overall, results provide a largely coherent pattern of selective effects that begin to form a comprehensive picture of alcohol related deficits.     

泰文和中文阅读过程中的眼动控制(中文)

This paper analyses some aspects of the eye movement behaviour of readers of Thai and Chinese. The main focus is on readers′landing site distributions on words and how these are affected by the lack of clear word boundary information due to the absence of inter-word spaces. Empirical evidence from Thai and Chinese readers suggest that readers can relatively accurately target word centres. We make the case that this accuracy can be accounted for by a default targetting model(effectively, the prior landing site distribution, in Bayesian terms)modulated by statistical cues about word beginnings available from word-initial character frequencies.     

阅读中关于眼动控制的研究进展

简要介绍阅读中眼动控制的研究进展,具体探讨了阅读过程中关于注视点停留位置、跳读、回视和注视时间等方面的研究,并对Morrison的眼动理论模型、O'Regan的战略战术模型和Reichle最新提出的E—Z读者模型进行了评述。最后,提出在吸收国外的这些研究成果的同时,要注意考虑中文与西文阅读的差异性。     

消失文本条件下认知控制的眼动研究

通过考察消失文本条件下的词频效应来探讨影响中文阅读眼动模式的控制因素。实验1发现当读者所注视的双字词在80ms后消失不会影响其正常阅读。实验2在实验1的基础上将材料的呈现时间设置为80ms,结果发现不论是正常阅读还是消失文本条件下均出现了显著的词频效应,结果支持眼动的认知控制模型。     

Afferent Information for Motor Control: The Role of Visual Information in Different Portions of the Movement

The question addressed in the present study was whether subjects (N = 24) can use visual information about their hand, in the first half of an aiming movement, to ensure optimal directional accuracy of their aiming movements. Four groups of subjects practiced an aiming task in either a complete vision condition, a no-vision condition, or in a condition in which their hand was visible for the first half [initial vision condition (IV)] or the second half of the movement [final vision condition (FV)]. Following 240 trials of acquisition, all subjects were submitted to a transfer test that consisted of 40 trials performed in a no-vision condition. The results indicated that seeing the hand early in movement did not help subjects to optimize either directional or amplitude accuracy. On the other hand, when subjects viewed their hand closer to the target, movements resulted that were as accurate as those performed under a complete vision condition. In transfer, withdrawing vision did not cause any increase in aiming error for the IV or the no-vision conditions. These results replicated those of Carlton (1981) and extended those of Bard and colleagues (Bard, Hay, & Fleury, 1985) in that they indicated that the kinetic visual channel hypothesized by Paillard (1980; Paillard & Amblard, 1985) appeared to be inoperative beyond 40deg of visual angle.