Sensitivity of Smoothness Measures to Movement Duration,Amplitude, and Arrests

ABSTRACT

Studies of sensory-motor performance, including those concerned with changes because of age, disease, or therapeutic intervention, often use measures based on jerk, the time derivative of acceleration, to quantify smoothness and coordination. However, results have been mixed: some researchers report sensitive discrimination of subtle differences, whereas others fail to find significant differences even when they are obviously present. One reason for this is that different measures have been used with different scaling factors. These measures are sensitive to movement amplitude or duration to different degrees. The authors show that jerk-based measures with dimensions vary counterintuitively with movement smoothness, whereas a dimensionless jerk-based measure properly quantifies common deviations from smooth, coordinated movement.     

Bimanual and Unimanual Convergent Goal-Directed Movement Times

Three experiments are reported, investigating the effects of using 1 or 2 hands when making convergent low index of difficulty (ID) and visually controlled movements (2 hands meeting together). The experiments involved movements in four different cases—a probe held in the right hand and moved to a target held in the stationary left hand, vice versa of this arrangement, both hands moving with the probe in the right hand and target in the left hand, and vice-versa of this arrangement. Experiments were the standard Fitts’ paradigm, moving a pin into a hole and a low-ID task. In Fitts’ task, 2-hand movements were faster than 1 hand only at higher IDs; this was also the case in the pin-to-hole transfer task and the movement times were lower when the pin was held in the preferred hand. Movements made with low ID showed a small effect of 1- or 2-handed movements, with the effective amplitude of the movement being reduced by about 20% when 2 hands were used.     

A Dual Process Account of Coarticulation in Motor Skill Acquisition

Many tasks, such as typing a password, are decomposed into a sequence of subtasks that can be accomplished in many ways. Behavior that accomplishes subtasks in ways that are influenced by the overall task is often described as “skilled” and exhibits coarticulation. Many accounts of coarticulation use search methods that are informed by representations of objectives that define skilled. While they aid in describing the strategies the nervous system may follow, they are computationally complex and may be difficult to attribute to brain structures. Here, the authors present a biologically- inspired account whereby skilled behavior is developed through 2 simple processes: (a) a corrective process that ensures that each subtask is accomplished, but does not do so skillfully and (b) a reinforcement learning process that finds better movements using trial and error search that is not informed by representations of any objectives. We implement our account as a computational model controlling a simulated two-armed kinematic “robot” that must hit a sequence of goals with its hands. Behavior displays coarticulation in terms of which hand was chosen, how the corresponding arm was used, and how the other arm was used, suggesting that the account can participate in the development of skilled behavior.     

Formative Versus Reflective Measurement: An Illustration Using Work–Family Balance

The aim of this article is to propose the formative measurement approach that can be used in various constructs of applied psychology. To illustrate this approach, the authors will (a) discuss the distinction between commonly used principal-factor (reflective) measures in comparison to the composite (formative) latent variable model, which is often applied in other disciplines such as marketing or engineering, and (b) point out the advantages and limitations of formative specifications using the example of the work–family balance (WFB) construct. Data collected from 2 large cross-sectional field studies confirm the reliability and validity of formative WFB measures as well as its predictive value regarding criteria of WFB (i.e., job satisfaction, family satisfaction, and life satisfaction). Last, the specific informational value of each formative indicator will be demonstrated and discussed in terms of practical implications for the assessment in different psychological fields.     

A Cerebral Hyperventilation Index for Electroencephalography

This study was an attempt to determine the effect of drive on probability learning. Each of two groups of Ss was divided into high- and low-drive groups on the basis of MAS scores. Each S was given 200 trials on a probability learning task, with 70 per cent reinforcement on one side and 30 per cent reinforcement on the other. At the .05 level, there was no difference between groups in probability choices, and neither group differed from the objective probability scores. The results are discussed in terms of the number of trials involved, the introduction of emotional arousal, and Hullian theory. On the basis of a comparison with the results of previous studies, it was suggested that investigators be cautious in generalizing probability learning results from one species to another.     

“Authoritarianism” and Agreement with Things Authoritative

The use of personality and attitudinal questionnaires in private executive and military samples is briefly reviewed. The need for evidence regarding the factor similarity of such questionnaires in comparative studies is noted. Such a comparative factorial study of an abbreviated version of the Shure-Meeker (11) Personality/Attitude Schedule (PAS) is reported. In terms of the general scales examined, three of the four scales emerge in both samples. The order of emergence, as well as the number and item content of the factors, differs slightly between the two samples. Caution is suggested in assuming factor similarity across samples in comparative studies utilizing the PAS and other personality and attitudinal instruments.     

A Natural Approach in Mental Health Practice: Occupational Adaptation Revealed

A single case study of the stories told by one occupational therapist about her clients in mental health settings is presented in this article. Qualitative analysis revealed key concepts of the role of the occupational therapist as defined by occupational adaptation theory, along with unique perspectives of occupational therapy in mental health settings. The outcome of this study is a demonstration of the unique insight occupational therapy brings to addressing client recovery in mental health settings, specifically from an occupational adaptation perspective. This insight should enlighten others as to the necessity of skilled occupational therapy in mental health settings.     

Standard Scores for the Bay Area Functional Performance Evaluation Task Oriented Assessment

This paper presents normative data for the Bay Area Functional Performance Evaluation Task Oriented Assessment using a sample of 266 patients drawn from five psychiatric in-patient hospitals in Western New York and Canada. Use of the means, standard deviations and standard scores is discussed and related to treatment planning.     

Exploring Sensory Integrative Treatment in Chronic Schizophrenia

An investigation of the efficacy of sensory integrative treatment of the psychiatric status and physical functioning of patients with chronic schizophrenia is reported. Patients were involved in sequenced sensory integrative treatment over a seventeen week period. Significant improvement was found in scores of the NOSIE-30 as well as on some of the usual idicators of sensory integrative status: thumb-finger opposition, diadochokinesis, eye pursuits and balance. Length of treatment time was linearly related to amount of improvement.