Boundary Distance Effects on Overshooting

Experiments with a subject-paced pursuit tracking task show that overshoot rate is dependent upon the distance between the target and the display boundary measured in the direction of movement, and that a previously noted inverse relationship with distance to the target is artifactual. The effect held for tasks with direct and reverse control-display relations, and for tasks with constant and variable target distances. The findings were consistent with Wetford’s (1968) hypothesis that a pursuit response is initiated with a ballistic, distance-covering, movement. Ralph Leonardo carried out extensive work in collecting data, Fred Hyde maintained the apparatus, and Georgie Green assisted in data analysis.     

Mathematical Models of Central Pattern Generators in Locomotion

Possible neural connective patterns and functions with respect to interlimb coordination are studied theoretically with a mathematical model of the central pattern generating system for cat locomotion. Activities in populations of neurons controlling limb joint flexors and extensors in all four limbs are represented by a system of nonlinear differential equations. Solutions of the system for various parameter values simulate various gaits of the cat. The model is shown to be capable of generating all gaits of the cat and accounting for corresponding phase changes in interlimb coordination. The model also exhibits smooth changes of gait, and smooth initiation and termination of stepping. Further, within each limb, muscle sequencing, step cycle phases, and flexor-extensor interactions can be studied. The model suggests that one of the simplest mechanisms for a central command system to change the gait is via inhibition of specific interlimb propriospinal pathways. In a final section, properties of both proposed single limb and interlimb models are reviewed with specific reference to planning future experimental and theoretical studies.     

Is the Critical Point for Aperture Crossing Adapted to the Person-Plus-Object System?

When passing through apertures, individuals scale their actions to their shoulder width and rotate their shoulders or avoid apertures that are deemed too small for straight passage. Carrying objects wider than the body produces a person-plus-object system that individuals must account for in order to pass through apertures safely. The present study aimed to determine whether individuals scale their critical point to the widest horizontal dimension (shoulder or object width). Two responses emerged: Fast adapters adapted to the person-plus-object system by maintaining a consistent critical point regardless of whether the object was carried while slow adapters initially increased their critical point (overestimated) before adapting back to their original critical point. The results suggest that individuals can account for increases in body width by scaling actions to the size of the object width but people adapt at different rates.     

Infant's perception of goal-directed actions performed by a mechanical device

The present work investigated whether by the end of the first year, infants interpret actions performed by a mechanical device as goal-directed and why they would do so. Using a modified version of the Woodward (1998) habituation paradigm, 9- and 12-month-old infants were tested in a condition in which they saw a mechanical claw performing an action (Study 1). When infants viewed the claw grasping and transporting objects to the back of a stage, 12-month-old but not 9-month-old infants interpreted the action as goal-directed. In Study 2, 9-month-olds received prior to habituation an information phase showing infants how a human held and operated the claw. This enrichment of infants’ knowledge enabled 9-month-old infants to interpret the action display as goal-directed. The role of the developing means-end understanding and tool-use for infants’ interpretation of actions performed by a mechanical device is discussed.     

Breaking and creating habits on the working floor: A field-experiment on the power of implementation intentions

Previous research has shown that implementation intentions are effective tools to promote new behavior. The present study aimed to provide the first evidence that conscious planning is an effective tool in replacing well-learned habits with new habits. This was tested in a field-experiment on repetitive behavior in the domain of recycling, using 109 employees of a tele-company as participants. Recycling behavior of the participants was observed by the actual amount of paper and the number of plastic cups in their personal wastebaskets. Following a pre-measure, participants were assigned to either implementation intention conditions, conditions in which an eye-catching facility was placed to promote recycling behavior, or control conditions. Recycling behavior was substantially improved in the facility as well as the implementation intention conditions in week 1 and week 2 and still 2 months after the manipulation. These data supported our hypothesis that planning breaks down unwanted habits and creates new ones.     

Choosing the shortest way to Mum: auditory guided rotation in 6- to 9-month-old infants

The purpose of this study was to investigate the use of auditory information for rotation of the shortest way in twelve 6- to 9-month-old sighted infants. Behavior was manipulated by means of an auditory stimulus presented in four different directional angles (90°, 112.5°, 135°, and 157.5°) to the right and to the left behind the infants, and in one non-directional angle (180°). Infants lay in a prone position and had magnetic trackers fastened to the head and body which measured their rotation direction and angular velocity. The results showed that infants not only consistently chose the shortest over the longest way, but also rotated with a higher peak angular velocity as the angle to be covered between themselves and the goal increased. The results did not show significant preferences for one particular rotation direction. The study can contribute to the understanding of the auditory system as a functional listening system where auditory information is used as a perceptual source for prospectively guiding behavior in the environment.     

儿童早期的动作发展对认知发展的作用

早期儿童与环境的相互作用通过动作来完成。儿童在与环境的相互作用过程中动作得到发展,与此同时也促进了认知发展。该文主要介绍了国内外的一些研究成果,阐述了爬行和手部动作对儿童认知发展的作用。发现儿童早期动作的发展是认知发展的外在表现,同时早期动作的发展也将促使儿童的认知发展不断高级化、复杂化。儿童通过爬行获得了运动经验,促进了感知觉的发展;而手部动作主要包括抓握动作和手势的发展,在儿童与环境的相互作用过程中则主要发挥着重要的中介作用。     

Goal relevance and artificial grammar learning

This investigation used a newly developed artificial grammar learning (AGL) paradigm in which participants were exposed to sequences of stimuli that varied in two dimensions (colours and letters) that were superimposed on each other. Variation within each dimension was determined by a different grammar. The results of two studies strongly suggest that implicit learning in AGL depends on the goal relevance of the to-be-learned dimension. Specifically, when only one of the two stimulus dimensions was relevant for their task (Experiment 1) participants learned the structure underlying the relevant, but not that of the irrelevant dimension. However, when both dimensions were relevant, both structures were learned (Experiment 2). These findings suggest that implicit learning occurs only in dimensions to which we are attuned. Based on the present results and on those of Eitam, Hassin, and Schul (2008) we suggest that focusing on goal relevance may provide new insights into the mechanisms underlying implicit learning.     

Leg Asymmetries and Coordination Dynamics in Walking

Models of interlimb coordination (H. Haken, J. A. S. Kelso, &; H. Bunz, 1985 Haken, H., Kelso, J. A. S. and Bunz, H. 1985. A theoretical model of phase transitions in human hand movements. Biological Cybernetics, 51: 347–356. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; P. N. Kugler &; M. T. Turvey, 1987 Kugler, P. N. and Turvey, M. T. 1987. Information, natural law, and the self-assembly of rhythmic movement, Hillsdale, NJ: Erlbaum.  [Google Scholar]) were tested in walking by examining the role of asymmetries between limbs. Participants walked on a treadmill with and without a metronome. Five asymmetry conditions were created via ankle loads of 0, 3, or 6 kg on either leg. With the metronome, participants matched the target period. Without the metronome, stride rate slowed as the mass was increased on either leg. The loads led to an increase in stride period that was predicted by Huygens’ law and the hybrid pendulum-spring model. In agreement with extended Haken–Kelso–Bunz model predictions, leg asymmetries led to deviations from antiphase coordination. Also, perception–action coordination was influenced by the asymmetry between the legs and metronome. In contrast, no predicted stability effects were observed. These findings reveal that some properties of interlimb coordination, apparent in laboratory-based tasks, can also be observed in human walking.