1,720,967 research outputs found
Coordination of locomotion and prehension
No full textItem does not contain fulltextAlthough locomotion and prehension are commonly coordinated in everyday life, little previous research has focused on this form of coordination. To address this neglected topic, we asked participants to stand a variable distance from a table, walk up to the table, and move an object on the tabletop to a new tabletop position, either to the right or to the left of the object's initial position and near or far from that initial position. For large manual displacements, which required a step after picking up the object, subjects preferred to stand on the foot opposite the direction of forthcoming manual displacement. By contrast, for small manual displacements, which did not require a step after picking up the object, subjects showed no support-leg preference when they grasped the object prior to manual displacement. The support-leg preferences at grasp time were apparently anticipated by participants as they walked up to the table, indicating considerable long-range planning of entire body positions associated with forthcoming object transfers
Planning my actions to accommodate yours: Joint action development during early childhood
No full textContains fulltext :
157554.pdf (Publisher’s version ) (Open Access)The planning and adjusting of one's actions in relation to an action partner is fundamental to smooth joint action. During their first years of life, children gradually become more engaged in joint actions. Here, we investigated whether and at what age children take their partner into account in their action plans to accommodate the other's actions. We focused on children's proactive planning (without prior experience) and flexible adjustment of action plans over time. In a behavioural study, we tested 96 children from four age groups (2½, 3, 3½ and 5 years) in a joint cup-stacking task. Children passed cups to their partner who had only one hand available (alternating over time) to build a tower. Children's response choices were assessed (i.e. passing the cup on the free or occupied side to their partner). The study yielded two major findings. At all ages, children proactively planned their actions in a way that accommodated their partner's actions. However, only by 3½ years did children start to flexibly integrate their partner into their action plans. Even at age 5, children only showed minimal adjustments to their action partner. Candidate processes underlying these developmental changes (e.g. inhibitory control, cognitive flexibility, perspective taking) are discussed.9 p
Moving the Arm at Different Rates: Slow Movements are Avoided
No full textContains fulltext :
89998.pdf (Publisher’s version ) (Closed access)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 it handheld dowel back and forth between 2 large Circular targets in time with a metronome Lit periods between 370 ins 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 ins. 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
The sense of agency during skill learning in individuals and dyads
No full textThe sense of agency has received much attention in the context of individual action but not in the context of joint action. We investigated how the sense of agency developed during individual and dyadic performance while people learned a haptic coordination task. The sense of agency increased with better performance in all groups. Individuals and dyads showed a differential sense of agency after initial task learning, with dyads showing a minimal increase. The sense of agency depended on the context in which the task was first learnt, as transfer from joint to individual performance resulted in an illusory boost in the sense of agency. Whereas the quality of performance related to the sense of agency, the generated forces to achieve the task did not. Our findings are consistent with a predictive model account at the perceptual level, such that the sense of agency relies most strongly on sharable perceptual information
Do people automatically track others' beliefs? Evidence from a continuous measure
No full textItem does not contain fulltextRecent findings suggest that tracking others' beliefs is not always effortful and slow, but may rely on a fast and implicit system. An untested prediction of the automatic belief tracking account is that own and others' beliefs should be activated in parallel. We tested this prediction measuring continuous movement trajectories in a task that required deciding between two possible object locations. We independently manipulated whether participants' belief about the object location was true or false and whether an onlooker's belief about the object location was true or false. Manipulating whether or not the agent's belief was ever task relevant allowed us to compare performance in an explicit and implicit version of the same task. Movement parameters revealed an influence of the onlooker's irrelevant belief in the implicit version of the task. This provides evidence for parallel activation of own and others' beliefs
Are you ready to jump? Predictive mechanisms in interpersonal coordination
No full textItem does not contain fulltextWhen two or more individuals intend to achieve a joint outcome, they often need to time their own actions carefully with respect to those of their coactors. Online perceptual feedback supports coordination by allowing coactors to entrain with and predict each other's actions. However, joint actions are still possible when no or little online feedback is available. The current study investigated the interplay between higher-level planning processes and motor simulation in a joint action task where online feedback was not available. Pairs of participants performed forward jumps (hops) next to each other with the instruction to land at the same time. They could neither see nor hear each other, but were informed about their own and the partner's jumping distance beforehand. The analysis of basic movement parameters showed that participants adjusted the temporal and spatial properties of the movement preparation and execution phase of their jumps to the specific difference in distance between themselves and their partner. However, this adaptation was made exclusively by the person with the shorter distance to jump, indicating a distribution of coactors' efforts based on task characteristics. A comparison with an individual bipedal coordination condition suggests that joint coordination might rely on similar principles as interlimb coordination. These findings are interpreted within a framework of motor simulation.14 p
Hand path priming in manual obstacle avoidance: Evidence for abstract spatiotemporal forms in human motor control
No full textItem does not contain fulltextPrevious research suggests that motor equivalence is achieved through reliance on effector-independent spatiotemporal forms. Here the authors report a series of experiments investigating the role of such forms in the production of movement sequences. Participants were asked to complete series of arm movements in time with a metronome and, on some trials, with an obstacle between I or more of the target pairs. In moves following an obstacle, participants only gradually reduced the peak heights of their manual jumping movements. This hand path priming effect, scaled with obstacle height, was preserved when participants cleared the obstacle with I hand and continued with the other, and it was modulated by future task demands. The results are consistent with the hypothesis that the control of movement sequences relies on abstract spatiotemporal forms. The data also support the view that motor programming is largely achieved by changing just those features that distinguish the next movement to be made from the movement that was just made
Higher-order action planning for individual and joint object manipulations
No full textContains fulltext :
115396.pdf (Publisher’s version ) (Open Access)Many actions involve multiple action steps, which raises the question how far ahead people plan when they perform such actions. Here, we examined higher-order planning for action sequences and whether people planned similarly or differently when acting individually or together with an action partner. For individual performances, participants picked up an object with one hand and passed it to their other hand before placing it onto a target location. For joint performances, they picked up the object and handed it to their action partner, who placed it onto the target location. Each object could be grasped at only two possible grasping positions, implying that the first selected grasp on the object determined the postures for the rest of the action sequence. By varying the height of the target shelf, we tested whether people planned ahead and modulated their grasp choices to avoid uncomfortable end postures. Our results indicated that participants engaged in higher-order planning, but needed task experience before demonstrating such planning during both individual and joint performances. The rate of learning was similar in the two conditions, and participants transferred experience from individual to joint performance. Our results indicate similarity in mechanisms underlying individual and joint action sequence planning
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
