Catching and matching bars with different orientations

The hypothesis that perception enslaves action is examined by assessing whether systematic distortions in perceptual judgments are reflected by inaccuracies in catching. In the first experiment, participants had to align manually the orientation of a reference bar placed at different distances in the frontoparallel plane. In the second experiment participants had to catch differently orientated moving bars, which became invisible at different distances from the interception point. In the matching experiment, systematic errors in the alignment of orientation were found in particular for oblique orientations, the magnitude of which increased with increasing distance of the reference bar. The inaccuracies in the final hand orientation during the catching task, however, did not mirror this pattern of deviations. The findings are interpreted to be more consistent with recent views that vision for perception (i.e., matching) and vision for action (i.e., catching) are dissociated than with the view that perception enslaves action.     

Roll-over characteristics of human walking on inclined surfaces

Roll-over characteristics of able-bodied human subjects walking on ramped surfaces were examined in this study. Ten subjects walked at their normal self-selected speed on a level surface, a 5-deg ramp, and a 10-deg ramped surface. Ramps were designed such that ground reaction forces and center of pressure of the ground reaction forces could be measured on their surfaces. This set-up facilitated calculation of the effective rockers that the ankle-foot (AF) and knee-ankle-foot (KAF) systems conformed to during single-limb stance (contralateral toe off to contralateral heel contact). Since our original "roll-over shapes" were characterized between heel contact and opposite heel contact, we label the shapes found during single-limb stance as "truncated roll-over shapes". We hypothesized that the ankle-foot system would adapt to the various surfaces, creating a roll-over shape that would change in orientation with different levels of inclination. The truncated AF roll-over shapes supported this hypothesis for uphill walking but did not support the hypothesis for downhill walking. However, truncated roll-over shapes of the KAF system did adjust their orientation to match both the positive and negative levels of surface inclination. In general, the ankle appears to be the main adapting joint when walking up inclined surfaces while the knee becomes important for the overall adaptation in downhill walking. Knowledge of physiological lower-limb roll-over characteristics on ramped surfaces may help in the development of biomimetic prostheses and orthoses that will automatically adapt to changes in walking surface inclination.     

微生物与人类进化

根据现代分子生物学知识和微生物知识,认为基因重组方式可能是人类进化的一种主要方式;并认为微生物能通过基因重组有效介导自身基因和各种生物基因流向人类;从原核生物到真核生物中广泛存在的转座作用可能是微生物介导的基因重组的一种重要方式;高等生物是由低等生物进化而来的,而微生物是进化上最早最低级的生命体。据此,认为微生物可能在人类进化和物种进化中起到了极其重要的作用,甚至可能是一种源泉的作用。其可能方式是     

Learning a pointing task with a kinematically redundant limb: Emerging synergies and patterns of final position variability

The study tested a hypothesis that practice of arm pointing movement can lead to a reorganization of the joint coordination reflected in the emergence of several synergies based on the same set of joints. In particular, involvement of the wrist may represent a choice by the central nervous system and not be driven by the typical “freezing-to-freeing” sequence. The effects of practice on the kinematic patterns and variability of a “fast and accurate” pointing movement using a pointer were studied. An obstacle was placed between the initial position and the target to encourage a curvilinear trajectory and larger wrist involvement. Practice led to a decrease in variability indices accompanied by an increase in movement speed of the endpoint and of the elbow and the shoulder, but not of the wrist joint. Five out of six subjects decreased the peak-to-peak amplitude of wrist motion. Before practice, the variability along the line connecting the endpoint to the shoulder (extent) was similar to that in the direction orthogonal to this line. After practice, variability was reduced along the extent, but not along the orthogonal direction perpendicular to this line. Prior to practice, indices of variability of the endpoint were lower than those of the marker placed over the wrist; after practice, the endpoint showed higher variability indices than the wrist. We interpret the data as consequences of the emergence of two synergies: (a) Pointing with a non-redundant set of the elbow and shoulder joints; and (b) keeping wrist position constant. The former synergy is based on a structural unit involving the elbow and the shoulder, while the latter is based on a structural unit that includes all the major arm joints.     

Participative work as an influence on human development

A number of business and industries in the United States and Europe have been experimenting with ways to involve more employees in organizational decision-making and problem-solving activities. Although the goal of such experiments in participative work is usually to improve productivity and enhance morale, there is evidence that working in such firms enhances adult development. This article reviews this evidence, focusing on how the experience of working in a participative milieu affects the individual in ways that are manifested off the job—in the family and community. Suggestions are made for future research that would involve developmental psychologists in helping work organizations experiment with planned social change.     

Sheldon's physical-psychical typology revisited

In order to clarify some of the general findings in the literature with respect to relationships between body type and the personality dimension extraversion/introversion, typical experimental paradigms common to this field were replicated but using the first-order factors (from the R. B. Cattell, H. W. Eber, & M. M. Tatsuoka (1970, Handbook for the sixteen personality factor questionnaire, Windsor: N.F.E.R.) analysis) that load on this continuum rather than the continuum itself. Use was made of standard statistical procedures as well as discriminant analysis. The most noteworthy finding was that subjects were able to utilize the first-order factor structure for the continuum extraversion/introversion in a discriminating manner and to assign such factors in a fairly clear-cut way to three extreme body types. Personality appraisals of the mesomorphic body type and an ideal type (composed by the subjects) were shown to be virtually identical. The most positive extravert characteristics were assigned to the endomorph body build and the most positive introvert characteristics to the ectomorph. No differences in personality appraisals by male (n = 50) and female (n = 50) subjects with the exception of factor Q₂ by the ectomorphic body type were found. Both male and female subjects showed a preference for the (male) mesomorphic body type although significant differences between male and female subjects in the pattern of their distribution of preferences over the three body types were found. While the results confirm previous findings, they also extend them by the use of a first-order factor structure for the continuum extraversion/introversion and by the introduction of the explanatory concepts “extravert of affect” and “extravert of action.”     

PROVIDING A LESS RESTRICTIVE ENVIRONMENT FOR PROFOUNDLY RETARDED PERSONS BY TEACHING INDEPENDENT WALKING SKILLS

A basic right of all handicapped persons is to live in the least restrictive environment possible. In this investigation, procedures were evaluated for teaching four institutionalized males with profound retardation necessary skills to increase their individual freedom of movement. Following baseline, a travel training program with a backward chaining format was implemented to teach each person to walk independently from his living area to school. Travel training included instructions, practice, praise, feedback, verbal reprimands, prompts, and edible reinforcers. Each resident began walking the entire distance to school independently during training and also began walking back to the living area, although the latter set of skills was not specifically trained. Following termination of the formal investigation, follow-up measures of 1 to 8 weeks showed the residents continued going to school independently. A survey of residential facilities in 43 states provided social validation for the seriousness of the problems associated with transporting seriously retarded persons to school. Also, time efficiency measures indicated that training independent travel resulted in reductions of staff time required in school transportation. Results were discussed in light of the potential contributions of behavior analysis in providing less restrictive environments for seriously handicapped persons.     

Less is not more: Further observations on nonlinguistic strategies

In an attempt to clarify the role of nonlinguistic preferences in children's responses to the words more and less, children 3–4 years of age were administered three tasks. Two of these required the child to indicate which of two arrays had more or less items, as instructed; the third task required the child to point to any one of two arrays. Children consistently selected the arrays with more items on all three tasks. The present finding of a response bias necessitates a reinterpretation of earlier studies of more and less. The results are discussed in terms of the full and partial semantics hypotheses as articulated by E. Clark.     

Availability and accessibility of information in the semantic memory of retarded and nonretarded adolescents

The availability of semantic information in storage and the accessibility of that information for retrieval were studied in retarded and nonretarded adolescents. In Experiment 1, 40 normal and 40 CA-equivalent (mean, 15 years) retarded subjects were required to retrieve information from semantic categories as well as to judge whether specific items were members of a given category. The results showed large IQ group differences on the retrieval task which could not be wholly accounted for by the items available in storage. Experiment 2 was designed as an attempt to remediate this retrieval deficit by introducing an organized retrieval plan consisting of subcategory cues. This organization facilitated retrieval as long as it was experimentally provided. Retrieval returned to its original level, however, when the cues were withdrawn. It was concluded that retarded persons had an accessibility deficit in addition to an availability deficit; one aspect of this accessibility deficit involved the failure to use spontaneously mnemonic strategies that were consistent with the semantic organization.