Quarterly journal of experimental psychology (2006), Jan 5, 2016
Cyclical upper-limb movements involuntarily deviate from a primary movement direction when the ac... more Cyclical upper-limb movements involuntarily deviate from a primary movement direction when the actor concurrently observes incongruent biological motion. We examined whether environmental context influences such motor interference during interpersonal observation-execution. Participants executed continuous horizontal arm movements while observing congruent horizontal or incongruent curvilinear biological movements with or without the presence of an object positioned as an obstacle or distractor. When observing a curvilinear movement, an object located within the movement space became an obstacle, and thus, the curvilinear trajectory was essential to reach into horizontal space. When acting as a distractor, or with no object, the curvilinear trajectory was no longer essential. For observing horizontal movements, objects were located at the same relative locations as in the curvilinear movement condition. We found greater involuntary movement deviation when observing curvilinear compa...
The absence of visual feedback leads to inaccurate representations of one's self-produced for... more The absence of visual feedback leads to inaccurate representations of one's self-produced force, through an "overcompensation" effect wherein central predictive mechanisms related to reafference result in self-generated forces being perceived as weaker than they are (Therrien et al., 2010; 2012; 2013). These findings hold significant safety implications in situations where repetitive force productions are a requirement of a work environment (e.g., assembly lines). Thus, the goal of this study was to explore this force salience effect in an applied setting to determine if full vision (FV), no vision (NV), or augmented vision (AV) in a motor task involving pinch grips would result in differential force productions. We hypothesized that, consistent with Therrien et al, performing such a task with FV would lead to the lowest pinch grip forces, while NV of the task would lead to compensatory force production. Furthermore, we introduced the concept of AV, through a closed-ci...
Recently our group forwarded a model of speed-accuracy relations in goal-directed reaching. A fun... more Recently our group forwarded a model of speed-accuracy relations in goal-directed reaching. A fundamental feature of our multiple process model was the distinction between two types of online regulation: impulse control and limb-target control. Impulse control begins during the initial stages of the movement trajectory and involves a comparison of actual limb velocity and direction to an internal representation of expectations about the limb trajectory. Limb-target control involves discrete error-reduction based on the relative positions of the limb and the target late in the movement. Our model also considers the role of eye movements, practice, energy optimization and strategic behavior in limb control. Here, we review recent work conducted to test specific aspects of our model. As well, we consider research not fully incorporated into our earlier contribution. We conclude that a slightly modified and expanded version of our model, that includes crosstalk between the two forms of ...
We examined the planning and control of goal-directed aiming movements in young adults with autis... more We examined the planning and control of goal-directed aiming movements in young adults with autism. Participants performed rapid manual aiming movements to one of two targets. We manipulated the diffi culty of the planning and control process by varying both target size and amplitude of the movements. Consistent with previous research, participants with autism took longer to prepare and execute movements, particularly when the index of diffi culty was high. Although there were no group differences for accuracy, participants with autism exhibited more temporal and spatial variability over the initial phase of the movement even though mean peak accelerations and velocities were lower than for control participants. Our results suggest that although persons with autism have diffi culty specifying muscular force, they compensate for this initial variability during limb deceleration. Perhaps persons with autism have learned to keep initial impulses low to minimize the spatial variability that needs to be corrected for during the online control phase of the movement.
The following study explored movement kinematics in two-component aiming contexts that were inten... more The following study explored movement kinematics in two-component aiming contexts that were intended to modulate the potential cost of overshoot or undershoot errors in up and down directions by having participants perform a second extension movement (Experiment 1) or a reversal movement (Experiment 2). For both experiments, the initial movement toward a downward target took longer, and had lower peak acceleration and peak velocity than upward movements. These movement characteristics may reflect a feedback-based control strategy designed to prevent energy-consuming limb modifications against gravitational forces. The between-component correlations of displacement at kinematic landmarks (i.e., trial-by-trial correlation between the first and second components) increased as both components unfolded. However, the between-component correlations of extensions were primarily negative, while reversals were positive. Thus, movement extensions appear to be influenced by the use of continuou...
Inhibition of return (IOR) has been shown to occur when an individual returns to a target locatio... more Inhibition of return (IOR) has been shown to occur when an individual returns to a target location (withinperson IOR) and when an individual moves to a location just engaged by another individual (between-person IOR). Although within-and between-person IOR likely result from the same inhibitory mechanisms, different processes must activate these mechanisms following the performance and observation of action. Consistent with the suggestion that the mirror neuron system may be responsible for activating the inhibitory mechanisms behind IOR on observation trials, between-person IOR was only detected under restricted viewing conditions known to activate mirror neurons. These results indicate that mirror neuron system may be involved in both higher-order and automatic cognitive behavior.
This article reviews the behavioral literature on the control of goal-directed aiming and present... more This article reviews the behavioral literature on the control of goal-directed aiming and presents a multiple-process model of limb control. The model builds on recent variants of Woodworth's (1899) two-component model of speed-accuracy relations in voluntary movement and incorporates ideas about dynamic online limb control based on prior expectations about the efferent and afferent consequences of a planned movement. The model considers the relationship between movement speed and accuracy, and how performers adjust their trial-to-trial aiming behavior to find a safe, but fast, zone for movement execution. The model also outlines how the energy and safety costs associated with different movement outcomes contribute to movement planning processes and the control of aiming trajectories. Our theoretical position highlights the importance of advance knowledge about the sensory information that will be available for online control and the need to develop a robust internal representation of expected sensory consequences. We outline how early practice contributes to optimizing strategic planning to avoid worst-case outcomes associated with inherent neural-motor variability. Our model considers the role of both motor development and motor learning in refining feed-forward and online control. The model reconciles procedural and representational accounts of the specificity-of-learning phenomenon. Finally, we examine the breakdown of perceptual-motor precision in several special populations (i.e., Down syndrome, Williams syndrome, autism spectrum disorder, normal aging) within the framework of a multiple-process approach to goal-directed aiming.
The Lombard effect describes the automatic and involuntary increase in vocal intensity that speak... more The Lombard effect describes the automatic and involuntary increase in vocal intensity that speakers exhibit in a noisy environment. Previous studies of the Lombard effect have typically focused on the relationship between speaking and hearing. Automatic and involuntary increases in motor output have also been noted in studies of finger force production, an effect attributed to mechanisms of sensory attenuation. The present study tested the hypothesis that sensory attenuation mechanisms also underlie expression of the Lombard effect. Participants vocalized phonemes in time with a metronome, while auditory and visual feedback of their performance were manipulated or removed during the course of the trial. We demonstrate that providing a visual reference to calibrate somatosensory-based judgments of current vocal intensity resulted in reduced expression of the Lombard effect. Our results suggest that sensory attenuation effects typically seen in fingertip force production play an important role in the control of speech volume.
Non-informative spatial cues presented prior to a goal-directed movement influence not only movem... more Non-informative spatial cues presented prior to a goal-directed movement influence not only movement initiation time but also the spatial characteristics of the movement trajectories. These trajectory effects are thought to stem from an integration of competing motor responses. In the present experiments, trajectories of rapid aiming movements were examined under the constraints of a cue-target inhibition of return (IOR) paradigm. Aiming movements were made to targets that were preceded by a cue stimulus in the same or different location. Four experiments were conducted in which the modality of the cue and target stimulus was manipulated across vision and audition. Although facilitation effects were present under the cross modality protocols, IOR effects were observed only for same cue-target pairings. At short stimulus onset asynchronies, limb trajectories deviated toward the target that had just been cued, particularly when the cue occurred in left space. These trajectory effects are consistent with response activation models of selective attention and movement preparation.
Two studies were conducted to examine the relation between the gambler's fallacy (GF) and attenti... more Two studies were conducted to examine the relation between the gambler's fallacy (GF) and attentional processes associated with inhibition of return (IOR). In Study 1, participants completed rapid aiming movements to equally probable targets presented to the left and right. They also completed a gambling protocol in which they bet on the illumination of either target. Consistent with the IOR phenomenon, participants were slower to initiate their movements on trial N + 1 when the target was the same as trial N. Participants with more pronounced IOR were more likely to switch betting behavior after a win than participants with a smaller index. This betting behavior was also related to a GF index measured by a questionnaire. In Study 2, participants performed both the aiming task and the betting task with a partner. Each participant performed two trials before ceding to the partner. Thus we were able to examine IOR and betting behavior as a function of the participant's own previous trial and their partner's previous trial. The IOR effect was robust both within and between-participants. Participants were more likely to maintain their bet following an unsuccessful outcome regardless of whether it was their own outcome or their partner's outcome. This type of betting behavior is consistent with the GF. Individual IOR scores were a reliable predictor of betting behavior and the questionnaire was also successful in predicting behavior. In addition, the within-person IOR indices covaried with the GF index derived from the questionnaire. In summary, there appears to be a relation between IOR and the GF. We suggest that early humans developed specialized attentional systems to deal with non-random environmental contingencies, and that the automatic processes associated with these systems are sometimes maladaptive in artificial environments in which the same contingencies do not hold.
Ten right-handed subjects performed 100 target-aiming movements with each hand. These movements w... more Ten right-handed subjects performed 100 target-aiming movements with each hand. These movements were directed toward a small target on the midline. On 60% of the trials, the target remained stationary. On other randomly placed trials, the tlclrget "jumped" to a location 3 em to the right (20%) or left (20%) of its original position when the cursor had travelled 6.5 em. Although no hand differences were evident in the control condition, the right hand acquired the new target location more quickly than the left hand when the target was perturbed in either direction. Kinematic data revealed that this advantage was not due to initiating an adjustment to the initial movement more rapidly, but rather less time decelerating the corrective movement. Movement adjustments on perturbed trials were implemented more rapidly in left space than right space independent of the hand doing the aiming. These asymmetries may reflect the differential role of the two cerebral hemispheres in the control of goal-directed movements.
This study was designed to examine the influence of age and the availability of vision on the per... more This study was designed to examine the influence of age and the availability of vision on the performance and kinematic characteristics of discrete aiming movements. Twelve young adults (19–25 years old) and 12 healthy older adults (62–82 years old) performed 130-mm aiming movements to targets with diameters of 5, 10, and 20 mm. On half the trial blocks, visual feedback about the aiming movement was eliminated upon movement initiation. Surprisingly, older adults were both as fast and as accurate as young adults regardless of the vision or target condition. While the velocity profiles of young and older adults were also similar, older adults exhibited a greater number of deviations in acceleration in both the vision and no-vision situations. Since these deviations are thought to reflect adjustments to the movement trajectory, older adults may rely more on visual and kinesthetic feedback for the control of goal-directed movement.
Posture prediction algorithms, particularly those that consider comfort (or discomfort), are typi... more Posture prediction algorithms, particularly those that consider comfort (or discomfort), are typically based on gross movements rather than on the finer movements of the upper extremity. However, understanding these finer movements, particularly during goal-directed reaching tasks, is critical to accurately predicting postures, and the associated potential injury risks, when using virtual ergonomic tools. Furthermore, it is expected that these finer movements will be highly sensitive to the planning processes used to perform sequential tasks, particularly when start and terminal orientation, terminal precision, and terminal force are manipulated. Thus, the purpose of this proposed study is to challenge the theory of the end-state comfort effect under conditions of varying terminal precision and exertion force requirements during both discrete and sequential goal-directed reaching tasks. It is expected that each of these manipulations (i.e. start and terminal orientation, terminal precision, terminal force, and number of movement sequences) will influence the chosen movement patterns. Understanding how each of these variables affects movement patterns will provide important information for the development of posture prediction algorithms for use with virtual ergonomics tools.
This study examined the performance of the upper limbs during responses to previously cued and un... more This study examined the performance of the upper limbs during responses to previously cued and un-cued locations. Participants made unimanual and bimanual responses under homologous and non-homologous muscular control, within a cuetarget (Experiment 1; n = 10), and a target-target (Experiment 2; n = 10) aiming protocol. The inhibition of return (IOR) to a target location was expected to increase with (a) an increase in the organization of the movement response required, and (b) the decrease in the muscular coupling under which the bimanual movement was performed. IOR was observed in both experiments when participants completed their movements in either the unimanual or homologous conditions, but not in the non-homologous condition. In addition, reaction times were significantly shorter when a movement preceded the response than when no manual response was made to the initial visual cue. The results indicate that common processing delays in response to exogenously cued targets are de...
Quarterly journal of experimental psychology (2006), Jan 5, 2016
Cyclical upper-limb movements involuntarily deviate from a primary movement direction when the ac... more Cyclical upper-limb movements involuntarily deviate from a primary movement direction when the actor concurrently observes incongruent biological motion. We examined whether environmental context influences such motor interference during interpersonal observation-execution. Participants executed continuous horizontal arm movements while observing congruent horizontal or incongruent curvilinear biological movements with or without the presence of an object positioned as an obstacle or distractor. When observing a curvilinear movement, an object located within the movement space became an obstacle, and thus, the curvilinear trajectory was essential to reach into horizontal space. When acting as a distractor, or with no object, the curvilinear trajectory was no longer essential. For observing horizontal movements, objects were located at the same relative locations as in the curvilinear movement condition. We found greater involuntary movement deviation when observing curvilinear compa...
The absence of visual feedback leads to inaccurate representations of one's self-produced for... more The absence of visual feedback leads to inaccurate representations of one's self-produced force, through an "overcompensation" effect wherein central predictive mechanisms related to reafference result in self-generated forces being perceived as weaker than they are (Therrien et al., 2010; 2012; 2013). These findings hold significant safety implications in situations where repetitive force productions are a requirement of a work environment (e.g., assembly lines). Thus, the goal of this study was to explore this force salience effect in an applied setting to determine if full vision (FV), no vision (NV), or augmented vision (AV) in a motor task involving pinch grips would result in differential force productions. We hypothesized that, consistent with Therrien et al, performing such a task with FV would lead to the lowest pinch grip forces, while NV of the task would lead to compensatory force production. Furthermore, we introduced the concept of AV, through a closed-ci...
Recently our group forwarded a model of speed-accuracy relations in goal-directed reaching. A fun... more Recently our group forwarded a model of speed-accuracy relations in goal-directed reaching. A fundamental feature of our multiple process model was the distinction between two types of online regulation: impulse control and limb-target control. Impulse control begins during the initial stages of the movement trajectory and involves a comparison of actual limb velocity and direction to an internal representation of expectations about the limb trajectory. Limb-target control involves discrete error-reduction based on the relative positions of the limb and the target late in the movement. Our model also considers the role of eye movements, practice, energy optimization and strategic behavior in limb control. Here, we review recent work conducted to test specific aspects of our model. As well, we consider research not fully incorporated into our earlier contribution. We conclude that a slightly modified and expanded version of our model, that includes crosstalk between the two forms of ...
We examined the planning and control of goal-directed aiming movements in young adults with autis... more We examined the planning and control of goal-directed aiming movements in young adults with autism. Participants performed rapid manual aiming movements to one of two targets. We manipulated the diffi culty of the planning and control process by varying both target size and amplitude of the movements. Consistent with previous research, participants with autism took longer to prepare and execute movements, particularly when the index of diffi culty was high. Although there were no group differences for accuracy, participants with autism exhibited more temporal and spatial variability over the initial phase of the movement even though mean peak accelerations and velocities were lower than for control participants. Our results suggest that although persons with autism have diffi culty specifying muscular force, they compensate for this initial variability during limb deceleration. Perhaps persons with autism have learned to keep initial impulses low to minimize the spatial variability that needs to be corrected for during the online control phase of the movement.
The following study explored movement kinematics in two-component aiming contexts that were inten... more The following study explored movement kinematics in two-component aiming contexts that were intended to modulate the potential cost of overshoot or undershoot errors in up and down directions by having participants perform a second extension movement (Experiment 1) or a reversal movement (Experiment 2). For both experiments, the initial movement toward a downward target took longer, and had lower peak acceleration and peak velocity than upward movements. These movement characteristics may reflect a feedback-based control strategy designed to prevent energy-consuming limb modifications against gravitational forces. The between-component correlations of displacement at kinematic landmarks (i.e., trial-by-trial correlation between the first and second components) increased as both components unfolded. However, the between-component correlations of extensions were primarily negative, while reversals were positive. Thus, movement extensions appear to be influenced by the use of continuou...
Inhibition of return (IOR) has been shown to occur when an individual returns to a target locatio... more Inhibition of return (IOR) has been shown to occur when an individual returns to a target location (withinperson IOR) and when an individual moves to a location just engaged by another individual (between-person IOR). Although within-and between-person IOR likely result from the same inhibitory mechanisms, different processes must activate these mechanisms following the performance and observation of action. Consistent with the suggestion that the mirror neuron system may be responsible for activating the inhibitory mechanisms behind IOR on observation trials, between-person IOR was only detected under restricted viewing conditions known to activate mirror neurons. These results indicate that mirror neuron system may be involved in both higher-order and automatic cognitive behavior.
This article reviews the behavioral literature on the control of goal-directed aiming and present... more This article reviews the behavioral literature on the control of goal-directed aiming and presents a multiple-process model of limb control. The model builds on recent variants of Woodworth's (1899) two-component model of speed-accuracy relations in voluntary movement and incorporates ideas about dynamic online limb control based on prior expectations about the efferent and afferent consequences of a planned movement. The model considers the relationship between movement speed and accuracy, and how performers adjust their trial-to-trial aiming behavior to find a safe, but fast, zone for movement execution. The model also outlines how the energy and safety costs associated with different movement outcomes contribute to movement planning processes and the control of aiming trajectories. Our theoretical position highlights the importance of advance knowledge about the sensory information that will be available for online control and the need to develop a robust internal representation of expected sensory consequences. We outline how early practice contributes to optimizing strategic planning to avoid worst-case outcomes associated with inherent neural-motor variability. Our model considers the role of both motor development and motor learning in refining feed-forward and online control. The model reconciles procedural and representational accounts of the specificity-of-learning phenomenon. Finally, we examine the breakdown of perceptual-motor precision in several special populations (i.e., Down syndrome, Williams syndrome, autism spectrum disorder, normal aging) within the framework of a multiple-process approach to goal-directed aiming.
The Lombard effect describes the automatic and involuntary increase in vocal intensity that speak... more The Lombard effect describes the automatic and involuntary increase in vocal intensity that speakers exhibit in a noisy environment. Previous studies of the Lombard effect have typically focused on the relationship between speaking and hearing. Automatic and involuntary increases in motor output have also been noted in studies of finger force production, an effect attributed to mechanisms of sensory attenuation. The present study tested the hypothesis that sensory attenuation mechanisms also underlie expression of the Lombard effect. Participants vocalized phonemes in time with a metronome, while auditory and visual feedback of their performance were manipulated or removed during the course of the trial. We demonstrate that providing a visual reference to calibrate somatosensory-based judgments of current vocal intensity resulted in reduced expression of the Lombard effect. Our results suggest that sensory attenuation effects typically seen in fingertip force production play an important role in the control of speech volume.
Non-informative spatial cues presented prior to a goal-directed movement influence not only movem... more Non-informative spatial cues presented prior to a goal-directed movement influence not only movement initiation time but also the spatial characteristics of the movement trajectories. These trajectory effects are thought to stem from an integration of competing motor responses. In the present experiments, trajectories of rapid aiming movements were examined under the constraints of a cue-target inhibition of return (IOR) paradigm. Aiming movements were made to targets that were preceded by a cue stimulus in the same or different location. Four experiments were conducted in which the modality of the cue and target stimulus was manipulated across vision and audition. Although facilitation effects were present under the cross modality protocols, IOR effects were observed only for same cue-target pairings. At short stimulus onset asynchronies, limb trajectories deviated toward the target that had just been cued, particularly when the cue occurred in left space. These trajectory effects are consistent with response activation models of selective attention and movement preparation.
Two studies were conducted to examine the relation between the gambler's fallacy (GF) and attenti... more Two studies were conducted to examine the relation between the gambler's fallacy (GF) and attentional processes associated with inhibition of return (IOR). In Study 1, participants completed rapid aiming movements to equally probable targets presented to the left and right. They also completed a gambling protocol in which they bet on the illumination of either target. Consistent with the IOR phenomenon, participants were slower to initiate their movements on trial N + 1 when the target was the same as trial N. Participants with more pronounced IOR were more likely to switch betting behavior after a win than participants with a smaller index. This betting behavior was also related to a GF index measured by a questionnaire. In Study 2, participants performed both the aiming task and the betting task with a partner. Each participant performed two trials before ceding to the partner. Thus we were able to examine IOR and betting behavior as a function of the participant's own previous trial and their partner's previous trial. The IOR effect was robust both within and between-participants. Participants were more likely to maintain their bet following an unsuccessful outcome regardless of whether it was their own outcome or their partner's outcome. This type of betting behavior is consistent with the GF. Individual IOR scores were a reliable predictor of betting behavior and the questionnaire was also successful in predicting behavior. In addition, the within-person IOR indices covaried with the GF index derived from the questionnaire. In summary, there appears to be a relation between IOR and the GF. We suggest that early humans developed specialized attentional systems to deal with non-random environmental contingencies, and that the automatic processes associated with these systems are sometimes maladaptive in artificial environments in which the same contingencies do not hold.
Ten right-handed subjects performed 100 target-aiming movements with each hand. These movements w... more Ten right-handed subjects performed 100 target-aiming movements with each hand. These movements were directed toward a small target on the midline. On 60% of the trials, the target remained stationary. On other randomly placed trials, the tlclrget "jumped" to a location 3 em to the right (20%) or left (20%) of its original position when the cursor had travelled 6.5 em. Although no hand differences were evident in the control condition, the right hand acquired the new target location more quickly than the left hand when the target was perturbed in either direction. Kinematic data revealed that this advantage was not due to initiating an adjustment to the initial movement more rapidly, but rather less time decelerating the corrective movement. Movement adjustments on perturbed trials were implemented more rapidly in left space than right space independent of the hand doing the aiming. These asymmetries may reflect the differential role of the two cerebral hemispheres in the control of goal-directed movements.
This study was designed to examine the influence of age and the availability of vision on the per... more This study was designed to examine the influence of age and the availability of vision on the performance and kinematic characteristics of discrete aiming movements. Twelve young adults (19–25 years old) and 12 healthy older adults (62–82 years old) performed 130-mm aiming movements to targets with diameters of 5, 10, and 20 mm. On half the trial blocks, visual feedback about the aiming movement was eliminated upon movement initiation. Surprisingly, older adults were both as fast and as accurate as young adults regardless of the vision or target condition. While the velocity profiles of young and older adults were also similar, older adults exhibited a greater number of deviations in acceleration in both the vision and no-vision situations. Since these deviations are thought to reflect adjustments to the movement trajectory, older adults may rely more on visual and kinesthetic feedback for the control of goal-directed movement.
Posture prediction algorithms, particularly those that consider comfort (or discomfort), are typi... more Posture prediction algorithms, particularly those that consider comfort (or discomfort), are typically based on gross movements rather than on the finer movements of the upper extremity. However, understanding these finer movements, particularly during goal-directed reaching tasks, is critical to accurately predicting postures, and the associated potential injury risks, when using virtual ergonomic tools. Furthermore, it is expected that these finer movements will be highly sensitive to the planning processes used to perform sequential tasks, particularly when start and terminal orientation, terminal precision, and terminal force are manipulated. Thus, the purpose of this proposed study is to challenge the theory of the end-state comfort effect under conditions of varying terminal precision and exertion force requirements during both discrete and sequential goal-directed reaching tasks. It is expected that each of these manipulations (i.e. start and terminal orientation, terminal precision, terminal force, and number of movement sequences) will influence the chosen movement patterns. Understanding how each of these variables affects movement patterns will provide important information for the development of posture prediction algorithms for use with virtual ergonomics tools.
This study examined the performance of the upper limbs during responses to previously cued and un... more This study examined the performance of the upper limbs during responses to previously cued and un-cued locations. Participants made unimanual and bimanual responses under homologous and non-homologous muscular control, within a cuetarget (Experiment 1; n = 10), and a target-target (Experiment 2; n = 10) aiming protocol. The inhibition of return (IOR) to a target location was expected to increase with (a) an increase in the organization of the movement response required, and (b) the decrease in the muscular coupling under which the bimanual movement was performed. IOR was observed in both experiments when participants completed their movements in either the unimanual or homologous conditions, but not in the non-homologous condition. In addition, reaction times were significantly shorter when a movement preceded the response than when no manual response was made to the initial visual cue. The results indicate that common processing delays in response to exogenously cued targets are de...
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