Minimal mimicry: Mere effector matching induces preference

Both mimicking and being mimicked induces preference for a target. The present experiments investigate the minimal sufficient conditions for this mimicry-preference link to occur. We argue that mere effector matching between one’s own and the other person’s movement is sufficient to induce preference, independent of which movement is actually performed. In Experiments 1 and 2, participants moved either their arms or legs, and watched avatars that moved either their arms or legs, respectively, without any instructions to mimic. The executed movements themselves and their pace were completely different between participants (fast circular movements) and targets (slow linear movements). Participants preferred avatars that moved the same body part as they did over avatars that moved a different body part. In Experiment 3, using human targets and differently paced movements, movement similarity was manipulated in addition to effector overlap (moving forward–backward or sideways with arms or legs, respectively). Only effector matching, but not movement matching, influenced preference ratings. These findings suggest that mere effector overlap is sufficient to trigger preference by mimicry.     

Dynamic Simulation and Static Matching for Action Prediction: Evidence From Body Part Priming

Accurately predicting other people's actions may involve two processes: internal real‐time simulation (dynamic updating) and matching recently perceived action images (static matching). Using a priming of body parts, this study aimed to differentiate the two processes. Specifically, participants played a motion‐controlled video game with either their arms or legs. They then observed arm movements of a point‐light actor, which were briefly occluded from view, followed by a static test pose. Participants judged whether this test pose depicted a coherent continuation of the previously seen action (i.e., “action prediction task”). Evidence of dynamic updating was obtained after compatible effector priming (i.e., arms), whereas incompatible effector priming (i.e., legs) indicated static matching. Together, the results support action prediction as engaging two distinct processes, dynamic simulation and static matching, and indicate that their relative contributions depend on contextual factors like compatibility of body parts involved in performed and observed action.     

Swinging into thought: Directed movement guides insight in problem solving

Can directed actions unconsciously influence higher order cognitive processing? We investigated how movement interventions affected participants’ ability to solve a classic insight problem. The participants attempted to solve Maier’s two-string problem while occasionally taking exercise breaks during which they moved their arms either in a manner related to the problem’s solution (swing group) or in a manner inconsistent with the solution (stretch group). Although most of the participants were unaware of the relationship between their arm movement exercises and the problem-solving task, the participants who moved their arms in a manner that suggested the problem’s solution were more likely to solve the problem than were those who moved their arms in other ways. Consistent with embodied theories of cognition, these findings show that actions influence thought and, furthermore, that we can implicitly guide people toward insight by directing their actions.     

Horizontal plane head stabilization during locomotor tasks

Frequency characteristics of head stabilization were examined during locomotor tasks in healthy young adults(N = 8) who performed normal walking and 3 walking tasks designed to produce perturbations primarily in the horizontal plane. In the 3 walking tasks, the arms moved in phase with leg movement, with abnormally large amplitude, and at twice the frequency of leg movement. Head-in-space angular velocity was examined at the predominant frequencies of trunk motion. Head movements in space occurred at low frequencies (< 4.0 Hz) in all conditions and at higher frequencies (> 4.0 Hz) when the arms moved at twice the frequency of the legs. Head stabilization strategies were determined from head-on-trunk with respect to trunk frequency profiles derived from angular velocity data. During natural walking at low frequencies (< 3.0 Hz), head-on-trunk movement was less than trunk movement. At frequencies 3.0 Hz or greater, equal and opposite compensatory movement ensured head stability. When arm swing was altered, compensatory movement guaranteed head stability at all frequencies. Head stabilization was successful for frequencies up to 10.0 Hz during locomotor tasks. Maintaining head stability at high frequencies during voluntary tasks suggests that participants used feedforward mechanisms to coordinate head and trunk movements. Maintenance of head stability during dynamic tasks allows optimal conditions for vestibulo-ocular reflex function.     

Lost in the move? Secondary task performance impairs tactile change detection on the body

Change blindness, the surprising inability of people to detect significant changes between consecutively-presented visual displays, has recently been shown to affect tactile perception as well. Visual change blindness has been observed during saccades and eye blinks, conditions under which people’s awareness of visual information is temporarily suppressed. In the present study, we demonstrate change blindness for suprathreshold tactile stimuli resulting from the execution of a secondary task requiring bodily movement. In Experiment 1, the ability of participants to detect changes between two sequentially-presented vibrotactile patterns delivered on their arms and legs was compared while they performed a secondary task consisting of either the execution of a movement with the right arm toward a visual target or the verbal identification of the target side. The results demonstrated that a motor response gave rise to the largest drop in perceptual sensitivity (as measured by changes in d′) in detecting changes to the tactile display. In Experiment 2, we replicated these results under conditions in which the participants had to detect tactile changes while turning a steering wheel instead. These findings are discussed in terms of the role played by bodily movements, sensory suppression, and higher order information processing in modulating people’s awareness of tactile information across the body surface.     

Horizontal Plane Head Stabilization During Locomotor Tasks

Frequency characteristics of head stabilization were examined during locomotor tasks in healthy young adults (N = 8) who performed normal walking and 3 walking tasks designed to produce perturbations primarily in the horizontal plane. In the 3 walking tasks, the arms moved in phase with leg movement, with abnormally large amplitude, and at twice the frequency of leg movement. Head-in-space angular velocity was examined at the predominant frequencies of trunk motion. Head movements in space occurred at low frequencies (< 4.0 Hz) in all conditions and at higher frequencies (> 4.0 Hz) when the arms moved at twice the frequency of the legs. Head stabilization strategies were determined from head-on-trunk with respect to trunk frequency profiles derived from angular velocity data. During natural walking at low frequencies (< 3.0 Hz), head-on-trunk movement was less than trunk movement. At frequencies 3.0 Hz or greater, equal and opposite compensatory movement ensured head stability. When arm swing was altered, compensatory movement guaranteed head stability at all frequencies. Head stabilization was successful for frequencies up to 10.0 Hz during locomotor tasks Maintaining head stability at high frequencies during voluntary tasks suggests that participants used feedforward mechanisms to coordinate head and trunk movements. Maintenance of head stability during dynamic tasks allows optimal conditions for vestibulo-ocular reflex function.     

The role of agency for perceived ownership in the virtual hand illusion

The rubber hand illusion shows that people can perceive artificial effectors as part of their own body under suitable conditions, and the virtual hand illusion shows the same for virtual effectors. In this study, we compared a virtual version of the rubber-hand setup with a virtual-hand setup, and manipulated the synchrony between stimulation or movement of a virtual “effector” and stimulation or movement of people’s own hand, the similarity between virtual effector and people’s own hand, and the degree of agency (the degree to which the virtual effector could be controlled by people’s own movements). Synchrony-induced ownership illusion was strongly affected by agency but not similarity, which is inconsistent with top-down modulation approaches but consistent with bottom-up approaches to ownership. However, both agency and similarity induce a general bias towards perceiving an object as part of one’s body, suggesting that ownership judgments integrate various sources of information.     

Control strategies when intercepting slowly moving targets

In 3 experiments, the authors investigated and described how individuals control manual interceptive movements to slowly moving targets. Participants (N = 8 in each experiment) used a computer mouse and a graphics tablet assembly to manually intercept targets moving across a computer screen toward a marked target zone. They moved the cursor so that it would arrive in the target zone simultaneously with the target. In Experiment 1, there was a range of target velocities, including some very slow targets. In Experiment 2, there were 2 movement distance conditions. Participants moved the cursor either the same distance as the target or twice as far. For both experiments, hand speed was found to be related to target speed, even for the very slowly moving targets and when the target-to-cursor distance ratios were altered, suggesting that participants may have used a strategy similar to tracking. To test that notion, in Experiment 3, the authors added a tracking task in which the participants tracked the target cursor into the target zone. Longer time was spent planning the interception movements; however, there was a longer time in deceleration for the tracking movements, suggesting that more visually guided trajectory updates were made in that condition. Thus, although participants scaled their interception movements to the cursor speed, they were using a different strategy than they used in tracking. It is proposed that during target interception, anticipatory mechanisms are used rather than the visual feedback mechanism used when tracking and when pointing to stationary targets.     

Ipsilesional Arm Motor Sequence Performance After Right and Left Hemisphere Damage

Aiming movements are part of daily activities but the brain hemispheres’ role in targeted aiming sequential movements is not fully clear. Start and execution of discrete and sequential tasks toward targets were analyzed in 10 individuals with left-hemisphere damage, 10 right-hemisphere–damaged, and 10 healthy ones. Arm movements were performed over a digitizing tablet, following stimuli on a monitor, from initial position toward right and left-positioned targets. Poststroke individuals used their ipsilesional arm and healthy individuals, both arms. Right-hemisphere–damaged individuals showed higher reaction time and left-hemisphere–damaged individuals, lower smoothness. Due to spatial demand of tasks, the right hemisphere played a major role in movement planning, while the left, in movement execution.     

Manual asymmetries in the preparation and control of goal-directed movements

The primary purpose of this experiment was to determine if left hand reaction time advantages in manual aiming result from a right hemisphere attentional advantage or an early right hemisphere role in movement preparation. Right-handed participants were required to either make rapid goal-directed movements to small targets or simply lift their hand upon target illumination. The amount of advance information about the target for a particular trial was manipulated by precuing a subset of potential targets prior to the reaction time interval. When participants were required to make aiming movements to targets in left space, the left hand enjoyed a reaction advantage that was not present for aiming in right space or simple finger lifts. This advantage was independent of the amount or type of advance information provided by the precue. This finding supports the movement planning hypothesis. With respect to movement execution, participants completed their aiming movements more quickly when aiming with their right hand, particularly in right space. This right hand advantage in right space was due to the time required to decelerate the movement and to make feedback-based adjustments late in the movement trajectory.     

The effects of movement direction and hemispace on estimates of distance traveled

BACKGROUND/HYPOTHESIS: The degree of attention directed to a stimulus and the presence of anisometric representations can alter the perception of the magnitude of a stimulus. We wanted to learn if normal right-handed subjects' estimates of distance traveled are influenced by the right-left direction or hemispace of movements. METHODS: We had blindfolded participants estimate the distance their arm was moved in a rightward or leftward direction, in right and left hemispace. Since we wanted subjects to estimate the distance traveled rather than compute the distance between the start and finish points, the subjects' arms were passively moved in sinusoidal trajectories at a constant speed. RESULTS: Subjects estimated leftward movements as longer than rightward movements, but there was no effect of hemispace. COMMENTS/CONCLUSIONS: People often attend more to novel than routine conditions and therefore participants might have overestimated the distance associated with leftward versus rightward movement because right-handed people more frequently move their right hand in a rightward direction and learn to read and write using rightward movements. Thus, leftward movements might be more novel and more attended than rightward movements and this enhanced directional attention might have influenced estimates of magnitude (distance).     

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.     

Effects of relative immobilization on the speaker's nonverbal behavior and on the dialogue imagery level

People generally display an important amount of gestural and motoric activity when speaking. Since recent data have shown the limits of an explanation of this activity in terms of nonverbal or bodily communication, the present study attempted to explore what would happen if subjects were impeded from making the principal movements they normally perform during a conversation. Subjects were led to hold a 50-minute conversation while sitting in an armchair devised to restrain their movements of the head, arms, hands, legs, and feet during part of the experiment. The main dependent variables consisted of nonverbal activity in body zones that remained free to vary: eyebrows, eyes, mouth, and fingers. During the phase of movement restriction, highly significant increases in activity were recorded in these zones, with subsequent return to base levels when the subject recovered free movements. Also, significant interactions of conditions of movements and subject's conversational role (speaker vs. listener) were observed for most of the variables. Samples of dialogues submitted to a computerized technique of content analysis revealed a significant decrease in the vividness of imagery during movement restriction.     

Working memory for movements

Movement to spatial targets that can, in principle, be carried out by more than one effector can be distinguished from movements that involve specific configurations of body parts. The experiments reported here investigate memory span for a series of hand configurations and memory span for a series of hand movements to spatial locations. Spans were produced normally, or in conditions in which a suppression task was carried out on the right or the left hand while the movements to be remembered were presented. All movements were recalled using the right hand. There were two suppression tasks. One involved repeatedly squeezing a tube and so changing the configuration of the hand, and the other involved tapping a repeated series of spatial targets. The spatial tapping task interfered with span for spatial locations when it was presented on either the right or the left hand but did not affect span for movement pattern. The movement suppression task interfered with memory for movement pattern when it was presented on either the right or the left hand, but did not interfere with span for spatial locations. It is concluded that memory for movement configurations involves different processes from those used in spatial tasks and that there may be a need for a subsystem of working memory that is specific for movement configuration.     

Motor processing modulates word comprehension

We evaluated whether movement modulates the semantic processing of words. To this end, we used homograph words with two meanings, one associated with hand movements (e.g., ‘abanico’, ‘fan’ in Spanish) or foot movements (‘bota’, ‘boot’ in Spanish), and the other not associated with movement (‘abanico’, ‘range’ in Spanish; ‘bota’, ‘wineskin’ in Spanish). After the homograph, three words were presented, and participants were asked to choose the word related to one of the two homograph meanings. The words could be either related to the motor meaning of the homograph (‘fan-heat’), to the non-motor meaning of the homograph (‘range-possibility’) or unrelated (‘fan-phone’). The task was performed without movement (simple condition) or by performing hand (Experiment 1) and foot (Experiment 2) movements. Compared with the simple condition, the performance of movement oriented the preference towards the motor meaning of the homograph. This pattern of results confirms that movement modulates word comprehension.     

裸露尤“物”:性客体化影响社会认知的眼动证据

客体化理论认为,对女性身体的关注会导致对其能力、热情和道德等社会属性评价的降低,然而以往研究缺乏直接证据。本研究以50名大学生为被试,采用眼动仪考察了对泳装图片和非泳装图片人物聪明程度评价过程中的眼动特征,结果发现:相比非泳装图片,被试对泳装图片人物的聪明程度评分更低;相比非泳装图片,被试对泳装图片人物胸部的注视点更多,注视时间和首次注视时间更长,对面孔的注视时间和首次注视时间更短。眼动特征表明,对泳装图片社会感知过程中存在客体化注视,直接且直观地支持了客体化理论。     

Typical predictive eye movements during action observation without effector-specific motor simulation

When watching someone reaching to grasp an object, we typically gaze at the object before the agent’s hand reaches it—that is, we make a “predictive eye movement” to the object. The received explanation is that predictive eye movements rely on a direct matching process, by which the observed action is mapped onto the motor representation of the same body movements in the observer’s brain. In this article, we report evidence that calls for a reexamination of this account. We recorded the eye movements of an individual born without arms (D.C.) while he watched an actor reaching for one of two different-sized objects with a power grasp, a precision grasp, or a closed fist. D.C. showed typical predictive eye movements modulated by the actor’s hand shape. This finding constitutes proof of concept that predictive eye movements during action observation can rely on visual and inferential processes, unaided by effector-specific motor simulation.     

Exploring specificity of speeded aiming movements: Examining different measures of transfer

Participants were trained and tested to move a mouse cursor from a start position to targets on a circular display in a perceptual-motor reversal condition, with horizontal, but not vertical, reversals. During training, some participants (experimental) moved to two targets either along a single diagonal axis (D1) or along both axes (D2). For D2, return movements from the targets were in the same direction as instructed movements to unpracticed targets. Others (control) trained on all targets. Testing always involved all targets. At test, movement times (to reach the target after leaving the start position) were shorter on trained than on untrained targets, especially for the D1 condition, documenting training specificity. However, movement times in the experimental conditions to new targets during testing were shorter than those in the control condition during training, documenting transfer of learning, with more transfer for D2 than for D1. Initiation times (to leave the start position after target onset) showed no transfer. The results provide evidence that specificity and transfer are not mutually exclusive and depend on the measure used to assess performance.     

Eye movements during multiple object tracking: where do participants look?

Similar to the eye movements you might make when viewing a sports game, this experiment investigated where participants tend to look while keeping track of multiple objects. While eye movements were recorded, participants tracked either 1 or 3 of 8 red dots that moved randomly within a square box on a black background. Results indicated that participants fixated closer to targets more often than to distractors. However, on 3-target trials, fixation was closer to the center of the triangle formed by the targets more often than to any individual targets. This center-looking strategy seemed to reflect that people were grouping the targets into a single object rather than simultaneously minimizing all target eccentricities. Here we find that observers deliberately focus their eyes on a location that is different from the objects they are attending, perhaps as a consequence of representing those objects as a group.     

Interlimb coordination following stroke

Studies investigating whether simultaneous bilateral movements can facilitate performance of the impaired limb(s) of stroke patients have returned mixed results. In the present study we compared unilateral limb performance (amplitude, cycle duration) with performance during an interlimb coordination task involving both homologous (both arms, both legs) and non-homologous (one arm, one leg) limbs in stroke participants (n=7) and healthy age-matched controls (n=7). In addition, the effect of on-line augmented visual feedback on interlimb coordination was investigated. Participants performed cyclical flexion-extension movements of the arms and legs in the sagittal plane paced by an auditory metronome (1 Hz). Movement amplitudes were larger and cycle durations shorter during homologous limb coordination than non-homologous coordination. Compared with unilateral movements both groups had reduced movement amplitudes and the stroke group increased cycle duration when interlimb coordination tasks were performed. These effects were most evident during non-homologous (arm and leg) coordination. No evidence of facilitation of the impaired limb(s) was found in any of the interlimb coordination conditions. Augmented visual feedback had minimal effect on the movements of control participants but lead to an increase of cycle duration for stroke participants.