Coordination Between Arm and Leg Movements During Locomotion

To evaluate the contrasting dynamical and biomechanical interpretations of the 2:1 frequency coordination between arm and leg movements that occurs at low walking velocities and the 1:1 frequency coordination that occurs at higher walking velocities, the authors conducted an experiment in which they quantified the effect of walking velocity on the stability of the frequency and phase coordination between the individual limb movements. Spectral analyses revealed the presence of 2:1 frequency coordination as a consistent feature of the data in only 3 out of 8 participants at walking velocities ranging from 1.0 to 2.0 km/h, in spite of the fact that the eigenfrequencies of the arms were rather similar across participants. The degree of interlimb coupling, as indexed by weighted coherence and variability of relative phase, was lower for the arm movements and for ipsilateral and diagonal combinations of arm and leg movements than for the leg movements. Furthermore, the coupling between all pairs of limb movements was found to increase with walking velocity, whereas no clear signs were observed that the switches from 2:1 to 1:1 frequency coordination and vice versa were preceded by loss of stability. Therefore, neither a purely biomechanical nor a purely dynamical model is optimally suited to explain these results. Instead, an integrative model involving elements of both approaches seems to be required.     

Behavioral Effects of Chronic Melatonin and Pregnenolone Injections in a Myelin Mutant Rat (taiep)

The taiep (tremor, ataxia, immobility, epilepsy, and paralysis) myelin mutant displays a number of locomotor deficits. Taiep rat gait is characterized by shorter stride and step lengths as well as by larger stride widths. Thirty-day-old taiep mutants were placed under a regimen of daily hormone injections for 60 days. Animals in Condition 1 received melatonin, those in Condition 2 received pregnenolone sulfate, and those in a third control condition received injections of saline. Following the injections, each taiep mutant's gait was analyzed. The animals that received melatonin and pregnenolone displayed significantly larger stride and step lengths than did the controls. In addition, the animals that received hormones displayed shorter stride widths than did the controls. These experimental effects are consistent with a normalization of gait. Possible cellular mechanisms of this behavioral effect are discussed.     

Effect of Nonspecific Chronic Low Back Pain on Walking Economy: An Observational Study

The authors investigated the effects of chronic low back pain (LBP) and walking speed (WS) on metabolic power and cost of transport (CT). Subjects with chronic nonspecific LBP (LBP group [LG]; n = 9) and healthy (control group [CG]; n = 9) were included. The test battery was divided into 3 blocks according to WS as follows: preferred self-selected speed (PS), and lower and higher than the PS. In each block, the volunteers walked 5 min, during which oxygen consumption was measured. Although without differences between groups, the LG had CT lower in slower speeds than in faster speeds. Walking speed affected CT only in the LG, which the group had the greatest walking economy at slower speeds.     

Postural and Locomotor Contributions to Affordance Perception

The authors sought to evaluate the relative importance of locomotor control and postural control in the perception of affordances. While seated in a stationary wheelchair, participants made a series of judgments about the minimum lintel height under which they could roll in the wheelchair. Prior to making judgments, participants were given brief (～2 min) experience with wheelchair locomotion. They expected that this practice would influence the accuracy of subsequent affordance judgments. During practice, participants moved under their own power (using their hands on the wheels) or with an experimenter pushing the wheelchair. Also during wheelchair locomotion the participant's head was restrained, or was not. Results revealed that head restraint during the practice session had no effect on the accuracy of subsequent judgments. By contrast, the judgments of participants who controlled locomotion during practice were significantly more accurate than the judgments of participants who had not controlled their locomotion during practice.     

Facilitation of Psychomotor Learning by Classically Differentiated Supplementary Feedback Cues

2 experiments on the control of psychomotor performance by classically differentiated supplementary feedback cues are reported. The first, conducted with 30 Ss as a replication of an earlier study, demonstrated again that otherwise ineffective supplementary cues can be transformed into highly effective regulators of psychomotor performance by differential conditioning procedures. The second, conducted with 78 Ss, showed that the effects of classically differentiated supplementary cues on tracking skill increased as a negatively accelerated function of the number of differentiation trials. Results were interpreted as exemplifying the operation of secondary drive and reinforcement principles, although the nonspecific transfer of arousal and/or warm-up effects were acknowledged as worthy alternatives.     

Shoulder Muscle Activity Dampens Arm Swing Motion When Altering Upper Limb Mass Characteristics During Locomotion

Weighting the arms during locomotion results in decreased swing motion and increased shoulder muscle activity. To determine the functional relevance of this activity, participants walked on a treadmill with the arms unweighted, or weighted unilaterally or bilaterally. Similar to past work, the weighted arms decreased in swing amplitude and increased their shoulder muscle activity. A close examination of shoulder muscle activities in specific regions of the arm swing cycle suggested these muscles primarily acted eccentrically for all weighting conditions. These findings suggest that the increased shoulder muscle activities when weighting the arms act to dampen the arms when the inertial characteristics of the arms are altered, as opposed to assisting in driving swing of the heavier arms.     

Investigating mechanisms of social support effectiveness: The case of locomotion motivation

Although social support can entail costs, individuals with a higher locomotion orientation, who are motivated to move and take action, benefit from support. Two dyadic studies tested whether perceived movement toward important goals would mediate the effect of recipients' locomotion motivation on positive outcomes in support contexts. In Study 1, couples completed a 10‐day diary and then recalled support interactions with their partner after the diary period. In Study 2, couples engaged in laboratory support interactions for important goals. Perceived goal movement mediated the effect of higher (vs. lower) locomotion on self‐reported ratings and coder ratings of support outcomes. Higher locomotion recipients may benefit in support contexts because they perceive they can move smoothly toward their goals.     

Identifying living and sentient kinds from dynamic information: the case of goal-directed versus aimless autonomous movement in conceptual change

To reason competently about novel entities, people must discover whether the entity is alive and/or sentient. Exactly how people make this discovery is unknown, although past researchers have proposed that young children--unlike adults--rely chiefly on whether the object can move itself. This study examined the effect of goal-directed versus aimless autonomous movement on children's and adults' attributions of biological and psychological capacities in an effort to test whether goal-directedness affects inferences across documented periods of change in biological reasoning. Half of the participants (adults, and 4-, 5-, 7-, and 10-year-olds; Ns=32) were shown videos of unfamiliar blobs moving independently and aimlessly, and the other half were shown videos of identical blobs moving identically but toward a goal. No age group was likely to attribute biological or psychological capacities to the aimless self-moving blobs. However, for 5-year-olds through adults, goal-directed movement reliably elicited life judgments, and it elicited more biological and psychological attributions overall. Adults differed from children in that goal-directed movement affected their attributions of biological properties more than their attributions of psychological properties. The results suggest that both young children and adults consider the capacity for goal-directed movement to be a decisive factor in determining whether something unfamiliar is alive, though other factors may be important in deciding whether the thing is sentient.     

Effect of Transient Perturbations of Short-Term Memory on Target-Directed Blind Locomotion

It is difficult to walk without vision to a nearby destination if there is a time delay between watching the destination and walking toward it. Indeed, path deviation occurred when delays were introduced before initiating straight ahead blindfolded walking (R. A. Tyrrell, K. K., Rudolph, B. G., Eggers, &; H. W. Leibowitz, 1993 Tyrrell, R. A., Rudolph, K. K., Eggers, B. G., &; Leibowitz, H. W. (1993). Evidence for the persistence of visual guidance information. Perception &; Psychophysics, 54, 431–438.[Crossref], [PubMed] , [Google Scholar]). The questions are whether the location of a 60-s delay in the walking path and whether performing a cognitive task during the delay influence the accuracy in reaching a previously seen target while walking without vision. Thirty young adults walked blindfolded and stopped when they believed they had reached a target at 8 m. Delays were 60 s in duration, were located at 0, 4, and 7 m, and involved waiting or backward counting. Significant differences were found between 0-m and 4-m delay locations for distance to target, distance travelled and path deviation (p < .05). Significant effect of backward counting during the 60-s delay was found at the 0-m delay for distance travelled (p < .05). The interaction between retaining visual guidance information during 60 s and performing a cognitive task likely influenced target-directed blind navigation.     

汉字表象加工中的心理位移研究

自谢帕德等首次进行心理旋转实验以来,表象加工方式的研究主要集中在心理旋转、心理扫描和认知地图等方面,而作为另一种加工方式的心理位移尚未有研究。本研究以人造汉字作为研究材料,试图证实在表象加工过程中存在心理位移加工方式,结果证实心理位移是表象的加工方式之一。在心理位移过程中,反应时间与构成新形象的两种刺激表象之间的呈现距离成正比;汉字构字过程中心理位移所需加工时间的临界点可能是0．5-1秒。