Specificity of Task Constraints and Effects of Visual Demonstrations and Verbal Instructions in Directing Learners' Search During Skill Acquisition

In the present study, the efficacy of visual demonstrations and verbal instructions as instructional constraints on the acquisition of movement coordination was investigated. Fifteen participants performed an aiming task on 100 acquisition and 20 retention trials, under 1 of 3 conditions: a modeling group (MG), a verbally directed group (VDG), and a control group (CG). The MG observed a model intermittently throughout acquisition, whereas the VDG was verbally instructed to use the model's movement pattern. Participants in the CG received neither form of instruction. Kinematic analysis revealed that compared with verbal instructions or no instructions, visual demonstrations significantly improved participants' approximation of the model's coordination pattern. No differences were found in movement outcomes. Coordination data supported the visual perception perspective on observational learning, whereas outcome data suggested that the modeling effect is mainly a function of task constraints, that is, the novelty of a movement pattern.     

The Effect of Fatigue on Learning and Performance of a Gross Motor Task

40 college males were sequentially assigned to 1 of 2 groups to examine the effects of induced physical fatigue upon the performance and learning of a gross motor task, the stabilometer. All Ss were given 32 practice trials over 3 practice sessions, with 48 hr. rest interpolated between sessions. Trials 1 and 2 were performed under control conditions (no fatigue) for both groups. The Experimental Group was then required to perform under conditions of physical fatigue during Trials 3-26. Trials 27-32 (Session 3) were performed under control conditions. The condition of fatigue was achieved on Trials 3-26 by having Ss pedal a bicycle ergometer until a heart rate of 180 beats/min was attained prior to each trial. The Control Group cancelled vowels. The results indicated that physical fatigue was detrimental to the performance and learning of the Experimental Group.     

Mass Perturbation of a Body Segment: 2. Effects on Interlimb Coordination

The shifts in relative phase that are observed when rhythmically coordinated limbs are submitted to asymmetric mass perturbations have typically been attributed to the induced eigenfrequency difference ($DL$oM) between the limbs. Modeling the moving limbs as forced linear oscillators, however, reveals that asymmetric mass perturbations may induce a difference not only in eigenfrequency (i.e., $DL$oM $$ 0) but also in the covarying low-frequency control gains (i.e., $DLk $$ 0). Because the inverse of the lowfrequency control gain (k) reflects the level of muscular torque (input) required for a particular displacement from equilibrium (output), asymmetric mass perturbations may result in an imbalance in the muscular torques required for task performance (related to $DLk $$ 0). Thus, it is possible that the effects attributed to $DL$oM were in fact mediated by $DLk. In 2 experiments, the authors manipulated $DLk and $DL$oM separately by applying mass perturbations to the lower legs of 9 participants. The relative phasing between the legs was not affected by $DLk, but manipulation of $DL$oM (while $DLk remained approximately 0) induced systematic relative phase shifts that were more pronounced for antiphase than for in-phase coordination. That indication that the coordination dynamics is indeed influenced by an imbalance in eigenfrequency is discussed vis-à-vis the question of how such a merely peripheral property may affect the underlying coordination process.     

Psychophysics of Kinesthesis

A horizontal straight-arm movement was used to determine the relationship between the physical stimulus continuum and the psychological continuum of kinesthetic extent of arm movement. A power function with an exponent of 1.075 best described this relationship. In addition, to classify extent of movement as belonging to either a prothetic or metathetic continuum, the category scale was derived. According to the functional criteria described by Stevens (1957), extent of movement was subserved by a metathetic process which would indicate that, for the present task, judgments were made through the use of positional cues rather than amplitude cues.     

Effects of Classically Differentiated Supplementary Feedback Cues on Tracking Skill

Although previous studies had shown that classical predifferentiation of green (CS-j and red (CS+) cues enabled them to facilitate tracking performance when used as supplementary indicators of correct and incorrect responses respectively, the studies were inconclusive concerning specific conditional properties versus nonspecific arousal consequences of the cues. A sample of 108 Ss was exposed to the same predifferentiation procedure, but then were subgrouped in terms of the kind of feedback signal received in tracking (no signal, red only, green only, both signals). A nonspecificity theory predicts subgroup equality of tracking performances while specificity theory predicts the dependence of performance level on the kind of signal received. Results corroborated previous findings and the view that tracking effects were reasonably attributable to the transfer of specific stimulus functions generated in the differentiation trials.     

Perceptual Estimates of Motor Skill Proficiency Are Constrained by the Stability of Coordination Patterns

This study demonstrated that motor skill proficiency ratings are constrained by the same order parameter dynamics that constrain action production and action perception processes. Participants produced rhythmic actions simulated by an animated stick figure of the human arm. The primary finding was that participants’ proficiency ratings covaried most with relative phase (φ) variability compared to mean relative phase. In-phase (φ = 0°) was produced with the least variability and received the highest proficiency rating, whereas the patterns φ = ±150° were attempted with the most variability and received the lowest proficiency ratings. A temporal delay in attempting to produce the animated pattern had a large impact on produced relative phase, yet had little impact on the proficiency ratings. Proprioceptive processes provide individuals information on motor skill proficiency. The lead or lag motion of the hand to forearm segment of the animated arm was identified consistently through visual processes and revealed asymmetries in the mapping of visual input to motor output. The results are consistent with concepts from the dynamic pattern theory of coordination and are discussed with regard to relative phase as an informational variable that constraints the perception-action system across many levels.     

The Influence of National Culture on the Perceived Fairness of Grading Procedures: A Comparison of the United States and China

Although the desire to be treated fairly is a fundamental human preference, perceptions of fair treatment can be influenced by cultural beliefs and values. For this article, the author used a scenario-based experimental study to examine students' fairness perceptions of grading procedures in 2 countries with distinct national cultures, China and the United States. The results suggest that culture can influence students' perceptions of the fairness of 2 aspects of procedural justice: voice and interpersonal justice. Chinese students were more likely to value interpersonal justice (i.e., being treated with dignity and respect, and being provided with explanations of grading procedures) and perceived the lack of interpersonal justice as less fair than did U.S. participants. In contrast, U.S. students were more likely to perceive voice (i.e., the opportunity to discuss and appeal a grading decision) as fair. These findings are connected to differences in the cultural values of the United States and China.     

Kinesthetic Aftereffect and Augmenting/Reducing: A Two-Session Procedure,and Hence Identification of Stimulus-Governed Subjects,is Contraindicated

A few of the recent researchers of kinesthetic aftereffect (KAE) as an index of augmenting/reducing have continued to employ a two-session procedure. Findings that have accrued in the past decade indicate (a) The first administration of KAE is a reliable (internally consistent) and valid index of augmenting-reducing; (b) there are carry-over effects from the first to the second administration that bias the second session's preinduction scores; (c) KAE scores from sessions after the first do not relate to first-session scores (low retest reliability) and do not measure augmenting/reducing; and (d) unless special procedures are undertaken to avoid using the biased second- (or later-) session preinduction scores, a KAE procedure involving more than one session is contraindicated. When we reached a similar conclusion earlier (Baker et al., 1974), Petrie (1974) disagreed, arguing that a two-session procedure was needed to identify and eliminate an atypical subgroup, the “stimulus governed.” The case for determining which subjects are stimulus-governed is assessed and found wanting. Except in special circumstances, a one-session KAE procedure, in which all preinduction trials precede the first exposure to aftereffect induction, is indicated.     

Examining the Relationships Between the Justice Facets and Turnover Intent: The Mediating Roles of Overall Justice and Psychological Strain

We examined how interpersonal justice from coworkers, the traditional justice facets (i.e., distributive, procedural, interpersonal, informational), and overall justice perceptions relate to employee psychological strain and turnover intentions in Canadian Armed Forces personnel. Specifically, we hypothesized that overall justice would mediate the relationships between the justice facets (including coworker justice) and strain, and strain would mediate the relationship between overall justice and turnover intent. We used a cross-sectional correlational design with personnel from 2 military units (total N = 218) as our sample. A 2-step structural equation modeling technique was used to evaluate our hypotheses. Support for our hypotheses was obtained with 1 exception: informational justice did not predict overall justice judgments. Our results suggest that employees’ reactions to individual justice events and different sources of justice exert their effects on strain and turnover intent indirectly through their impact on a global evaluation of justice in their work environment.