Kinematic analysis of goal-directed aims made against early and late perturbations: an investigation of the relative influence of two online control processes

Examination of goal-directed movements has evidenced two processes of visually regulated online control: early trajectory control that operates to make movement adjustments on the basis of limb velocity comparisons to internally generated models of the expected limb velocity, and late trajectory control that uses allocentric information about the limb and target positions. The results of experiments using illusory perturbations suggest that the two systems have an additive influence on movement outcome, and are relatively independent. In this theoretical context, three experiments were conducted in which actual perturbations to the aiming limb dynamics and the tasks demands were introduced. Compressed air expulsed through a stylus, in the direction of, or opposite to, that of the movement was used to impact limb velocity and the target location was moved at movement initiation to impact late evaluation of target and limb position. The results of the compressed air-only and moving target-only conditions replicated the previous evidence of early and late control, respectively. Interestingly, movement accuracy measures yielded an interactive effect of the two perturbations when presented in tandem. It appears that the perturbations prompted parallel operation of the two control processes.     

The influence of mastery‐avoidance goals on performance improvement

Two experiments focused on examining the influence of mastery‐avoidance goals on performance improvement, and more specifically, on mastery‐avoidance goals grounded in an intrapersonal standard. That is, herein, mastery‐avoidance goals entail striving to avoid doing worse than one has done before. Both experiments demonstrated that in a multiple‐trial context, mastery‐avoidance goals are deleterious for performance improvement relative to mastery‐approach, performance‐approach, and performance‐avoidance goals, and a no goal baseline. The findings were shown to be independent of participants' perceptions of goal difficulty, and were consistent not only across methodology but also across type of participant (undergraduates versus individuals in the workforce), and type and length of achievement task (a verbal skills task versus an ecologically valid managerial competencies exercise). Copyright © 2009 John Wiley & Sons, Ltd.     

The Butterfly,the Mole and the Sage

Zhuangzi chooses a butterfly as a metaphor for transformation, a sighted creature whose inherent nature contains, and symbolizes, the potential for transformation from a less valued state to a more valued state. If transformation is not to be valued; if, according to a recent article by Jung Lee, ‘there is no implication that it is either possible or desirable for the living to awake from their dream’, why not tell a story of a mole awakening from a dream? This would be a more perfect story. There would be no point of a mole awakening since (setting aside tactile, olfactory, auditory and taste sensations for the purpose of the example), there is no way to distinguish between the world of the mole's imagination and the real world that is forever unavailable to a mole. In addition, Zhuangzi relates the story of the coming of a great sage in which it is clearly stated that ‘Only at the ultimate awakening shall we know that this is the ultimate dream’. Such textual evidence both from the choice of metaphors and evidential passages indicates that the message of the Zhuangzi is not epistemological relativity, but one of transformation from a state of intellectual blindness to a state of true understanding.     

Speech perception and motor control in children with Down syndrome.

Twelve children with and without Down syndrome (DS) performed eight subtests of an apraxia battery to determine under what conditions children with DS had difficulty performing representational and nonrepresentational gestures. Participants with DS also completed a dichotic listening test. Participants with DS performed just as well as control participants on all aspects of the apraxia battery except a subtest in which they were required to pantomime tool use from verbal instruction. This suggests that children with DS have difficulty generating an action from memory following verbal instruction. Given the sufficient context or visual demonstration, children with DS performed similar to the other participants. As well, there was a great deal of within-group variability for dichotic listening ear advantage. Participants with a greater left ear advantage on the dichotic listening test committed more errors on an imitation test that also included a verbal component than participants with a greater right ear advantage.     

Color and psychological functioning: the effect of red on performance attainment

This research focuses on the relation between color and psychological functioning, specifically, that between red and performance attainment. Red is hypothesized to impair performance on achievement tasks, because red is associated with the danger of failure in achievement contexts and evokes avoidance motivation. Four experiments demonstrate that the brief perception of red prior to an important test (e.g., an IQ test) impairs performance, and this effect appears to take place outside of participants' conscious awareness. Two further experiments establish the link between red and avoidance motivation as indicated by behavioral (i.e., task choice) and psychophysiological (i.e., cortical activation) measures. The findings suggest that care must be taken in how red is used in achievement contexts and illustrate how color can act as a subtle environmental cue that has important influences on behavior.     

Are there age-related differences in learning to optimize speed, accuracy, and energy expenditure?

Studies of age-related differences in manual aiming have indicated that older adults take longer to complete their movements than their younger counterparts because they tend to rely on time-consuming feedback-based control processes. Many authors have suggested that the reliance on feedback is the result of a "play-it-safe" strategy that has been adopted to compensate for a deterioration in accurate and consistent force generation. That is, perhaps because older adults know that their motor systems are not as reliable as the systems were at a younger age, they plan shorter movements that conserve time and space for feedback control to correct their programmed actions. The vast majority of the previous studies that have revealed these age-related differences in aiming, however, have used computer-based tasks that involve the transformation of perceptual into motor space. In the present experiment, older and younger adults completed real aiming movements over three sessions. The results suggest that, when acting in a real environment, the main difference between older and younger adults in movement execution lies in the efficient use of response-related feedback, not in the programming of movement.     

Comparing derived and acquired acceleration profiles: 3-D optical electronic data analyses

Advances in technology in the last century have provided the opportunity to observe human behavior in one, two, and three dimensions with higher recording frequencies and greater spatial accuracy. Consequently, detailed analyses of individual trials and composite measures of multiple movement trajectories are possible. However, 3-D data have often been analyzed by performing independent analyses of the limb trajectory along each axis. Essentially, analyses of individual axes are often inappropriate as movement in each axis can contribute to the overall trajectory. Employing such methods can compound error throughout the analysis process. The purpose of this study was to determine appropriate post hoc and real-time 3-D optoelectronic data reduction procedures for manual aiming movements. Rapid goal-directed movements were recorded using an Optotrak and triaxial accelerometer. Data were separately subjected to second order Butterworth filters employing low-cut frequencies of 6-24 Hz in 2 Hz increments. Subsequently, acceleration profiles were derived by double differentiating the individual position profiles and then calculating the resultant acceleration profile. In addition, acceleration profiles were also calculated by finding the resultant position and the total distance traveled each frame prior to double differentiation. Root mean square error between the derived and acquired profiles was employed as our main dependent measure. Trajectories reduced with the total distance procedure produced the lowest root mean square error. The results are important for experimenters analyzing 3-D data post hoc and those implementing real-time manipulations.     

Effects of response priming and inhibition on movement planning and execution

The authors used a precueing method to examine the effects of response priming and inhibition on goal-directed action. Participants (N = 18) completed aiming movements to 1 of 2 locations following predictive (80% cued), nonpredictive (50% cued), and antipredictive (20% cued) precues at 1 of the 2 possible target locations. Consistent with previous research, participants responded more quickly to targets at cued locations than to targets at uncued locations in the 80% condition, and more quickly to targets presented at the uncued than to those presented at cued locations in the 50% and 20% conditions. As predicted by models of action-centered selective attention, movement trajectories deviated away from the cued location in the 50% condition. Movement trajectories were also altered in the 80% and the 20% conditions. Movements directed to the uncued location deviated away from the cued location in the 80% condition, whereas movements directed to the cued location deviated away from the uncued location in the 20% condition. The authors explain the latter trajectory results as a strategy of overcompensation.     

Amygdala and hippocampal activity during acquisition and extinction of human fear conditioning

Previous functional magnetic resonance imaging (fMRI) studies have characterized brain systems involved in conditional response acquisition during Pavlovian fear conditioning. However, the functional neuroanatomy underlying the extinction of human conditional fear remains largely undetermined. The present study used fMRI to examine brain activity during acquisition and extinction of fear conditioning. During the acquisition phase, participants were either exposed to light (CS) presentations that signaled a brief electrical stimulation (paired group) or received light presentations that did not serve as a warning signal (control group). During the extinction phase, half of the paired group subjects continued to receive the same treatment, whereas the remainder received light alone. Control subjects also received light alone during the extinction phase. Changes in metabolic activity within the amygdala and hippocampus support the involvement of these regions in each of the procedural phases of fear conditioning. Hippocampal activity developed during acquisition of the fear response. Amygdala activity increased whenever experimental contingencies were altered, suggesting that this region is involved in processing changes in environmental relationships. The present data show learning-related amygdala and hippocampal activity during human Pavlovian fear conditioning and suggest that the amygdala is particularly important for forming new associations as relationships between stimuli change.