Eye movements in action disorganization syndrome: A single case analysis

This study examines eye movements made by a patient with action disorganization syndrome (ADS) as everyday tasks are performed. Relative to both normal participants and control patients, the ADS patient showed normal time-locking of eye movements to the subsequent use of objects. However, there were proportionately more unrelated fixations, and more fixations concerned with locating objects irrelevant to the immediate action, compared with control participants. The data suggest a dissociation between normal eye movement patterns for control of visually guided actions such as reaching and grasping, and abnormal eye movements between object-related fixations. The implications for understanding ADS are discussed.     

New insights on eye blindness and hand sight: Temporal constraints of visuo-motor networks

Pioneer experiments on saccadic suppression have shown that this effect is not followed by motor disorientation: Conscious perception of a target displacement can be dissociated from correct manual target reaching. It has subsequently been demonstrated that movement corrections with the same latency and spatial characteristics can be produced in conditions allowing perceptual awareness of perturbation of a target as in condition inducing saccadic suppression. In addition to the qualitative dissociation between motor performance and conscious awareness, quantitative temporal dissociations in action can be observed by manipulating different features of the visual target. When the target of an ongoing simple action is perturbed, a temporal advantage is found for responses to perturbations of location relative to colour and shape. Furthermore, there seems to be a temporal advantage for automatic motor corrections made in response to a target displacement as compared to other responses (other ongoing movement adjustments, movement interruption, conditional motor response such as pressing a key, verbal response, delayed matching-to-sample tasks). Thus, this paper reviews evidence for the fact that the temporal characteristics of any given response to a stimulus are dependent both on the sensory processes and on the type of response generated. Accordingly, identification responses (such as verbal report) to a visual stimulus are much slower than motor corrections of an ongoing movement in response to a target location change because of different processing times of the stimulus features (“What” compared to “Where”) and of the response itself (“What” compared to “How”). The existence of two continua (What/Where and What/How) is proposed between these two extreme stimulus- response combinations. This model may be a useful framework to better understand visuo-motor transformations and the network of connections between visual and motor areas.     

Seeking spirituality through physicality in schools: learning from ‘Eastern movement forms’

This paper argues that we might learn from the ways in which Eastern movement forms with a self-cultivation focus approach the development of spirituality through physicality. It also argues that these movement forms have potential to assist in the development of children’s spirituality in school and Physical Education (PE) settings. First, the paper highlights a distinctive orientation to self-cultivation at the heart of which lies a focus on uniting body and mind through regular movement-based practice. Next, differing relationships between these movement forms and spirituality are identified as: fragments of established religious spirituality; spiritual exercise; and secular religious spirituality. Finally, three common pedagogic principles of these movement forms are highlighted and applied to the school and PE context: identifying self-identity and emotions; prioritising direct experience and changing the body-self through practice. It is suggested that these understandings of self-cultivating Eastern movement forms may help sensitise educators to approaching the cultivation of spirituality through physicality in schools using, not only Eastern movement forms but also Western activities delivered in accordance with these principles.     

The Impact of Strategic Trajectory Optimization on Illusory Target Biases During Goal-Directed Aiming

During rapid aiming, movements are planned and executed to avoid worst-case outcomes that require time and energy to correct. As such, downward movements initially undershoot the target to avoid corrections against gravity. Illusory target context can also impact aiming bias. Here, the authors sought to determine how strategic biases mediate illusory biases. Participants aimed to Müller-Lyer figures in different directions (forward, backward, up, down). Downward biases emerged late in the movement and illusory biases emerged from peak velocity. The illusory effects were greater for downward movements at terminal endpoint. These results indicate that strategic biases interact with the limb-target control processes associated with illusory biases. Thus, multiple control processes during rapid aiming may combine and later affect endpoint accuracy (D. Elliott et al., 2010 Elliott, D., Hansen, S., Grierson, L. E. M., Lyons, J., Bennett, S. J., &; Hayes, S. J. (2010). Goal-directed aiming: two components but multiple processes. Psychological Bulletin, 136, 1023–1044.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]).     

Translating Cognition Into Action

This experiment examined the role of two forms of visual guidance in facilitating the translation of cognitive representations into action. Subjects matched a modeled action pattern either concurrently with the model or after the modeled display. They then either did or did not visually monitor their actions during tests of production accuracy in the model’s absence. Acquisition of the cognitive representation was assessed periodically. Concurrent matching of modeled actions or visual monitoring of productions both increased the level of observational learning. The more accurate the cognitive representation, the more skilled were subsequent reproductions of the modeled actions. After acquiring proficiency in converting cognition to action, subjects maintained their level of performance accuracy even though modeled and visual-monitoring guidance were withdrawn. These results are in accordance with the theory that cognitive representation mediates response production and that corrective adjustments through visual guidance aid in the translation of conception into action.     

The Simple Copy Task: Detecting Higher Order Visual Processing Deficits in Schizophrenia,Dementia, and Movement Disorder Groups

The Simple Copy Task (SCT) is a figure copying test with inherent appeal due to its short administration time, graded task difficulty, varied stimuli, and potential to eliminate floor effects. Despite this, there is a lack of data regarding its construct validity and diagnostic utility. The present study compared SCT performance of schizophrenia (n = 29), dementia (n = 64), and movement disorder (n = 12) groups with that of unmatched healthy control participants (n = 49). Movement disorder patients committed a high degree of misplacement errors, whereas dementia patients tended to omit items, add extraneous detail, and perseverate. The schizophrenia group was most similar to the dementia group in their performance on the SCT, committing primarily omission and perseveration errors. The SCT was most closely related to the Rey Complex Figure Task (r = 0.68, p < .01) and the Block Design Task (r = 0.62, p < .01). Age (r = ?0.14, p < .01) and education (r = 0.35, p < .01) effects were present; however, there was no impact of gender and handedness. Taken together, these findings provide support for the utility of the task and directions for clinical interpretation.     

Muscle Damaging Exercise Affects Isometric Force Fluctuation as well as Intraindividual Variability of Cognitive Function

Healthy untrained men (N = 11) were asked to perform 10 series of 12 repetitions of knee eccentric extension (EE) at 160° per second. Quadriceps muscle torques evoked by electrical stimulation at 20 Hz (P20) and 100 Hz (P100), maximal voluntary isometric contraction torque (MVC), maximal isokinetic concentric torque (IT) at 30° per second, voluntary activation index (VA), simple reaction time (RTs), complex reaction time (RTc), and torque variability at 30% of MVC were measured before EE, immediately after EE, and 60 min and 24 hr after EE. MVC, IT, P20, P100, and VA decreased significantly after EE and remained depressed 24 hr later. Torque variability increased significantly after EE. Average RTs and RTc did not change after EE, whereas intraindividual variability in RTs and RTc increased significantly after EE.     

Weber (Slope) Analyses of Timing Variability in Tapping and Drawing Tasks

Timing variability in continuous drawing tasks has not been found to be correlated with timing variability in repetitive finger tapping in recent studies (S. D. Robertson et al., 1999; H. N. Zelaznik, R. M. C. Spencer, & R. B. Ivry, 2002). Furthermore, the central component of timing variability, as measured by the slope of the timing variance versus the square of the timed interval, differed for tapping and drawing tasks. On the basis of those results, the authors posited that timing in tapping is explicit and as such uses a central representation of the interval to be timed, whereas timing in drawing tasks is implicit, that is, the temporal component is an emergent property of the trajectory produced. The authors examined that hypothesis in the present study by determining the linear relationship between timing variance and squared duration for tapping, circle-drawing, and line-drawing tasks. Participants (N = 501 performed 1 of 5 tasks: finger tapping, line drawing in the x dimension, line drawing in the y dimension, continuous circle drawing timed in the x dimension, or continuous circle drawing timed in the y dimension. The slopes differed significantly between finger tapping, line drawing, and circle drawing, suggesting separable sources of timing variability. The slopes of the 2 circle-drawing tasks did not differ from one another, nor did the slopes of the 2 line-drawing tasks differ significantly, suggesting a shared timing process within those tasks. Those results are evidence of a high degree of specificity in timing processes.     

Moving the Arm at Different Rates: Slow Movements are Avoided

Qualitative and quantitative changes characterize locomotion and rhythmic interlimb coordination at different speeds. Legs and hands do not move more or less quickly; they also adopt different relative coordination patterns. In the present article, the authors asked whether similar transitions occur for unimanual hand movements when speed is slowed below the preferred speed. Participants moved a handheld dowel back and forth between 2 large circular targets in time with a metronome at periods between 370 ms and 1667 ms. The authors analyzed the kinematics of participants’ movements at each period and found that proportional dwell time and number of peaks in the velocity profile increased as driving periods increased. Path lengths and peak velocities remained relatively constant for driving periods exceeding 800 ms. Participants made only gradual changes to their movement parameters, so that they went from a continuous mode to a more discrete mode of behavior for longer driving periods. Thus, unlike for rhythmic bimanual movements or locomotory patterns, there are quantitative but no clear qualitative changes for unimanual movements. The results suggest that participants tried to move close to their preferred tempo at different rates, and that they avoided moving slowly.     

Visuokinesthetic Realignment in a Video-Controlled Reaching Task

The authors investigated the accuracy of horizontal pointing movements toward a visual target viewed on a vertical video monitor; the view included a directional distortion between perceptual and action spaces. Although accurate coding of the movement vector in a relative (visual) system of coordinates has been found to occur when there is a prismatic perturbation, provided that the hand and the target are continuously visible, such accurate performance has never been reported for video-controlled situations with larger deviations. To evaluate whether visual relative coding is task specific or depends on the magnitude of the induced misalignment, the authors manipulated the intensity of directional perturbation (10° or 40°) in a video-controlled task. Whatever the directional bias, participants (N = 40) were initially inaccurate but adapted quickly within a few trial rehearsals, with a concomitant recalibration of segmental proprioception. In contrast with prism studies, relative coding of the hand-to-target vector seemed not to be operative in video-controlled situations, suggesting that target location is specified in an egocentric system of reference that includes hand-related proprioceptive signals, despite the presence of a (consciously) detected misalignment between visual and kinesthetic systems.