Movement observation affects movement execution in a simple response task

The present study was designed to examine the hypothesis that stimulus-response arrangements with high ideomotor compatibility lead to substantial compatibility effects even in simple response tasks. In Experiment 1, participants executed pre-instructed finger movements in response to compatible and incompatible finger movements. A pronounced reaction time advantage was found for compatible as compared to incompatible trials. Experiment 2 revealed a much smaller compatibility effect for less ideomotor-compatible object movements compared to finger movements. Experiment 3 presented normal stimuli (hand upright) and flipped stimuli (hand upside-down). Two components were found to contribute to the compatibility effect, a dynamic spatial compatibility component (related to movement directions) and an ideomotor component (related to movement types). The implications of these results for theories about stimulus-response compatibility (SRC) as well as for theories about imitation are discussed.     

Language-induced motor perturbations during the execution of a reaching movement

In a recent study Boulenger et al. (2006) found that processing action verbs assisted reaching movement when the word was processed prior to movement onset and interfered with the movement when the word was processed at movement onset. The present study aimed to further corroborate the existence of such cross-talk between language processes and overt motor behaviour by demonstrating that the reaching movement can be disturbed by action words even when the words are presented delayed with respect to movement onset (50 ms and 200 ms). The results are compared to studies that show language-motor interaction in conditions where the word is presented prior to movement onset and are discussed within the context of embodied theories of language comprehension.     

Age-related differences in the integration of sensory information during the execution of a bimanual coordination task

Young (n = 7) and elderly (n = 7) subjects performed bimanual coordination patterns in the transverse plane according to the in-phase or antiphase mode. Sensory information was manipulated through visual (with or without vision of the limbs) and proprioceptive input (with or without vibratory stimuli on one limb). Movement patterns with vibrations showed higher deviations from the intended relative phase than did those without vibrations. This finding suggests that the proprioceptive information induced by the vibrations and the movement interfered, leading to a disruption of the coordination patterns. In addition, as compared with the elderly, the young subjects performed more stable movements under normal circumstances but were more strongly affected by vibratory stimuli during the performance of in-phase movements. During antiphase movements, both age groups experienced a decrease of pattern stability. Furthermore, the absence or presence of visual feedback influenced the performance of the young subjects more than that of the elderly. The presence of vision led to stable in-phase movements, whereas a decrease of pattern stability was observed for antiphase movements. In general, these results demonstrate that manipulation of feedback sources affects young subjects more than elderly ones, and this can be related to a reduced sensory sensitivity as a function of aging.     

Modification in movement accuracy in the triphasic pattern during a rapid forearm-flexion task

The present study was designed to investigate modifications in the triphasic EMG pattern during a forearm-flexion task at maximum speed which required three levels of movement accuracy. 36 subjects participated in 4 training sessions, performing a total of 200 repetitions of each movement. The fastest movement time was associated with the least accurate movement task. Likewise, the slowest movement time was found for the movement requiring the greatest accuracy. Differences in the duration and amplitude of agonist 1 activity, the start of agonist 2 activity, and the start and amplitude of antagonist activity were observed for the three movements. The results indicate that agonist 1 provides a propulsive force to initiate limb movement. The antagonist EMG activity was thought responsible for braking and correcting limb movement. Modifications in agonist 2 activity suggest this burst is related to movement velocity.     

Overcoming spontaneous patterns of coordination during the acquisition of a complex balancing task.

Learning in complex tasks is usually conceived as the problem of mastering the multiple and redundant degrees of freedom of the system. To reduce control requirements, two different strategies are conceivable. The first one consists of a "freezing-freeing" process for most articular joints to reduce the number of active biomechanical degrees of freedom to be managed. The second strategy consists of introducing rigid couplings between the oscillators building the system. In this case, learning implies the dissolution of initial couplings and the emergence of new, more task-specific couplings. The goal of our study was to analyze the spontaneous coordination of beginners and its development in a complex balancing task on a stabilometer, and to examine the emergence of these two strategies. Our results showed that beginners were characterized by strong couplings between the joints of the lower limbs. During learning, new and more task-specific couplings emerged that reflected a new organization of the trunk and a decoupling of some joints of the lower limbs that were initially coupled during the first few trials.     

Impact of elicited mood on movement expressivity during a fitness task

The purpose of the present study was to evaluate the impact of four mood conditions (control, positive, negative, aroused) on movement expressivity during a fitness task. Motion capture data from twenty individuals were recorded as they performed a predefined motion sequence. Moods were elicited using task-specific scenarii to keep a valid context. Movement qualities inspired by Effort-Shape framework (Laban & Ullmann, 1971) were computed (i.e., Impulsiveness, Energy, Directness, Jerkiness and Expansiveness). A reduced number of computed features from each movement quality was selected via Principal Component Analyses. Analyses of variance and Generalized Linear Mixed Models were used to identify movement characteristics discriminating the four mood conditions. The aroused mood condition was strongly associated with increased mean Energy compared to the three other conditions. The positive and negative mood conditions showed more subtle differences interpreted as a result of their moderate activation level. Positive mood was associated with more impulsive movements and negative mood was associated with more tense movements (i.e., reduced variability and increased Jerkiness). Findings evidence the key role of movement qualities in capturing motion signatures of moods and highlight the importance of task context in their interpretations.     

Kinematic parameters of hand movement during a disparate bimanual movement task in children with unilateral Cerebral Palsy

Children with unilateral Cerebral Palsy (uCP) experience problems performing tasks requiring the coordinated use of both hands (bimanual coordination; BC). Additionally, some children with uCP display involuntary symmetrical activation of the opposing hand (mirrored movements). Measures, used to investigate therapy-related improvements focus on the functionality of the affected hand during unimanual or bimanual tasks. None however specifically address spatiotemporal integration of both hands. We explored the kinematics of hand movements during a bimanual task to identify parameters of BC. Thirty-seven children (aged 10.9 ± 2.6 years, 20 male) diagnosed with uCP participated. 3D kinematic motion analysis was performed during the task requiring opening of a box with their affected- (AH) or less-affected hand (LAH), and pressing a button inside with the opposite hand. Temporal and spatial components of data were extracted and related to measures of hand function and level of impairment. Total task duration was correlated with the Jebsen–Taylor Test of Hand Function in both conditions (either hand leading with the lid-opening). Spatial accuracy of the LAH when the box was opened with their AH was correlated with outcomes on the Children’s Hand Use Experience Questionnaire. Additionally, we found a subgroup of children displaying non-symmetrical movement interference associated with greater movement overlap when their affected hand opened the box. This subgroup also demonstrated decreased use of the affected hand during bimanual tasks. Further investigation of bimanual interference, which goes beyond small scaled symmetrical mirrored movements, is needed to consider its impact on bimanual task performance following early unilateral brain injury.     

Consistent reproduction of movement sequences during acquisition of a pursuit tracking task

A pursuit tracking task is used as a vehicle to investigate the manner in which response consistency is affected by practice. Detailed examination of movement patterns shows that subjects can reproduce the mid-phase of a movement relatively consistently while the accelerative and decelerative phases of the movement remain highly variable. The findings are discussed with reference to Sparrow's 1983 concept of efficiency in conjunction with Norman and Shallice's 1980 model of automated action.     

Motor planning and execution in left- and right-handed individuals during a bimanual grasping and placing task

The issue of handedness has been the topic of great interest for researchers in a number of scientific domains. It is typically observed that the dominant hand yields numerous behavioral advantages over the non-dominant hand during unimanual tasks, which provides evidence of hemispheric specialization. In contrast to advantages for the dominant hand during motor execution, recent research has demonstrated that the right hand has advantages during motor planning (regardless of handedness), indicating that motor planning is a specialized function of the left hemisphere. In the present study we explored hemispheric advantages in motor planning and execution in left- and right-handed individuals during a bimanual grasping and placing task. Replicating previous findings, both motor planning and execution was influenced by object end-orientation congruency. In addition, although motor planning (i.e., end-state comfort) was not influenced by hand or handedness, motor execution differed between left and right hand, with shorter object transport times observed for the left hand, regardless of handedness. These results demonstrate that the hemispheric advantages often observed in unimanual tasks do not extend to discrete bimanual tasks. We propose that the differences in object transport time between the two hands arise from overt shifting visual fixation between the two hands/objects.     

Evaluation algorithm for eye movement patterns during a problem solving task]

Cognitive processes are accompanied by eye movements, which are interrupted by fixations of an almost infinite number of points in the visual field. To investigate these processes, a systematic analysis of those movements is required to structure the long sequences of fixations. This task is possible if there are interrelationships between the ongoing thought processes and the fixations. Such interrelationships may manifest themselves through certain patterns of eye movements. It often happens that subsets of visual points are being looked at repeatedly. This is because a cognitive connection among the subset's elements is being discovered or created by such repetition. The method presented here attempts to achieve automatic recognition of fixation point patterns. Its usefulness is demonstrated using data from an experiment where eye movements were recorded while subjects were solving Raven Test items. The method may be characterized as a variant of time series analysis for nominal data. It is suitable for non-numerical data in general.     

An investigation of changes in auditory sensitivity during the performance of a mental task

Auditory thresholds were measured while the subject was relaxed and while he was doing mental arithmetic. Thresholds were lowered under the second condition. Some possible explanations are briefly considered.     

Characterizing visual behaviour in a lineup task

Eye tracking was used to monitor participants' visual behaviour while viewing lineups in order to determine whether gaze behaviour predicted decision accuracy. Participants viewed taped crimes followed by simultaneous lineups. Participants (N = 34) viewed 4 target‐present and 4 target‐absent lineups. Decision time, number of fixations and duration of fixations differed for selections vs. non‐selections. Correct and incorrect selections differed only in terms of comparison‐type behaviour involving the selected face. Correct and incorrect non‐selections could be distinguished by decision time, number of fixations and duration of fixations on the target or most‐attended face and comparisons. Implications of visual behaviour for judgment strategy (relative vs. absolute) are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

The role of the primary motor cortex during skill acquisition on a two-degrees-of-freedom movement task

One can partially eliminate motor skills acquired through practice in the hours immediately following practice by applying repetitive transcranial stimulation (rTMS) over the primary motor cortex. The disruption of acquired levels of performance has been demonstrated on tasks that are ballistic in nature. The authors investigated whether motor recall on a discrete aiming task is degraded following a disruption of the primary motor cortex induced via rTMS. Participants (N = 16) maintained acquired performance levels and patterns of muscle activity following the application of rTMS, despite a reduction in corticospinal excitability. Disruption of the primary motor cortex during a consolidation period did not influence the retention of acquired skill in this type of discrete visuomotor task.     

The effect of timing of a perturbation on the execution of a lifting movement

Anticipation to the mass magnitude is important in lifting, but underestimation of a mass, in contrast to overestimation, does not cause major movement disturbances. This may be caused by corrections in muscle activity before the object is actually lifted. This study was designed to assess the importance of these corrections during the loading phase for the execution of a lifting movement when the mass is underestimated. Ten subjects lifted a box (1.6 kg), of which the mass was increased by 10 kg without them knowing so. The mass was added either before the box had been lifted from the ground (perturbation before lift-off, PBL) or right perturbation after lift-off (PAL). In the PBL condition back muscle activity was increased before lift-off. Even though this early corrective response could obviously not occur in the PAL condition, the lifting movement was executed without clear problems. In sum, corrections in muscle activity before lift-off are not necessary for adequate correction of a perturbation induced by an unexpected heavier object.     

The impact of working memory load on task execution and online plan adjustment during multitasking in a virtual environment

Three experiments investigated the impact of working memory load on online plan adjustment during a test of multitasking in young, nonexpert, adult participants. Multitasking was assessed using the Edinburgh Virtual Errands Test (EVET). Participants were asked to memorize either good or poor plans for performing multiple errands and were assessed both on task completion and on the extent to which they modified their plans during EVET performance. EVET was performed twice, with and without a secondary task loading a component of working memory. In Experiment 1, articulatory suppression was used to load the phonological loop. In Experiment 2, oral random generation was used to load executive functions. In Experiment 3, spatial working memory was loaded with an auditory spatial localization task. EVET performance for both good- and poor-planning groups was disrupted by random generation and sound localization, but not by articulatory suppression. Additionally, people given a poor plan were able to overcome this initial disadvantage by modifying their plans online. It was concluded that, in addition to executive functions, multiple errands performance draws heavily on spatial, but not verbal, working memory resources but can be successfully completed on the basis of modifying plans online, despite a secondary task load.     

Cognitive processing and motor execution in the lexical decision task: a developmental study

We investigated lexical decision making in children and adults by analyzing spatiotemporal characteristics of responses involving a hand movement. Children’s and adults’ movement trajectories were assessed in three tasks: a lexical decision task (LDT), a pointing task that involved minimal cognitive processing, and a symbol task requiring a simple binary decision. Cognitive interference on motor performance was quantified by analyzing movement characteristics in the LDT and symbol task relative to the pointing task. Across age groups, movements in the LDT were less smooth, slower, and more strongly curved to the opposite response option, and these interference effects decreased steadily with age. Older children showed stronger interference effects than did adults, even though their reaction times were similar to adults’ performance. No comparable effects were found in the symbol task, indicating that task characteristics such as response mapping and decision selection alone are not able to explain the developmental differences observed in the LDT. Our results indicate substantial overlap between cognitive processing and motor execution in the LDT in children that is not captured by computational models of visual word recognition and cognitive development.     

Eliminative and enumerative behaviour in a conceptual task

P. C. Wason's paper “On the Failure to Eliminate Hypotheses in a Conceptual Task” is criticized on the grounds that the task set is in important respects untypical of problem solving situations in general. It is suggested that few or no subjects are “Eliminators” in Wason's sense and that although many are “Enumerators” in his sense, enumerative behaviour is a function of the situation. An experiment is reported in which it appears that modification to the situation can sharply reduce the incidence of enumerative behaviour and increase the subject's chance of success at an early stage. The frequency with which hypotheses are directly eliminated is shown to be very low in all groups.