Children's Memory for Locations Visited: Importance of Movement and Choice

In 2 experiments, the effect of active or passive mobility and active or passive choice experiences on children's memory for locations visited while retrieving puzzle pieces hidden in a large room were examined. In the first experiment, fifty-two 6- and 7-year-old children were randomly assigned to 1 of 4 training conditions: active choice-active movement, active choice-passive movement, passive choice-active movement, and passive choice-passive movement. After 3 training trials, all children were tested in the active choice-active movement condition. A 2 (movement) x 2 (choice) factorial multivariate analysis of variance revealed a significant main effect for movement. Children who had moved actively to find the puzzle pieces in the training trials had (a) a greater percentage correct, (b) more correct visits between errors, and (c) a later visit of first error than children who had been passively pushed in a wheelchair. Making active choices in training did not significantly affect performance. A second experiment used identical procedures but tested 32 children with mobility dif-difficulties who regularly used a wheelchair because of either cerebral palsy or spina bifida. Children from this group who moved actively during training to retrieve the puzzle pieces also performed better on testing. Implications of the results for children with disabilities and for developmental theory are discussed.     

Age Changes in Interlimb Coupling and the Development of Bimanual Coordination

Changes in interlimb coupling, and their role in the development of bimanual coordination, were studied longitudinally in 6- to 12-month-old infants (N = 6). Infants were observed while they were reaching for simple objects of 2 different sizes. Their use of a uni-versus bimanual strategy for reaching as well as the coupling of their bimanual movements were compared; progress in bimanual coordination of complementary movements was evaluated on 8 different bimanual tasks. The bimanual tasks involved an asymmetrical cooperation between the 2 hands. Although spatiotemporal coupling of bimanual reaching movements did not decrease during the age period studied, infants around 7 months of age used their 2 hands infrequently for reaching. Occurrences of bimanual reaching were particularly low at the session preceding the first bimanual success at a bimanual task. This suggests that the temporal coincidence between greater independence of the 2 hands and progress in bimanual coordination of complementary movements acts in 2 directions: Infants may be more at ease when using their 2 hands in differentiated patterns as the hands move less in synchrony, but, in turn, they may be less likely to move their hands in synchrony as the anticipate mirror manipulations of the object less. The frequency of bimanual reaches increased toward the end of the 1st year. This might have been caused by an increase in the repertoire of bimanual asymmetrical object manipulations and by the fact that the development of bimanual coordination allows infants to manipulate objects with complementary movements even after a bimanual approach toward the object.     

Schedule interactions involving punishment with pigeons and humans

The principal aim of the present experiments was to assess whether punishment increased or decreased the rate of unpunished behavior (contrast and induction, respectively) for which reinforcement rate was held constant, with physical and nonphysical punishers (electric shock and response cost), pigeon and human subjects, signaled and unsignaled components (multiple and mixed schedules), and the presence or absence of a blackout period between components. Across the three experiments there were 20 punishment conditions. Induction was found in nine of those, less consistent response-rate reduction was found in three, contrast was found in four, and in four there was no change in responding from conditions without punishment. Contrast occurred consistently only with multiple schedules during the first exposure to electric-shock punishment. Induction and no change, however, were found with every combination of the independent variables studied. Four conclusions regarding the interactions between punished and unpunished responding emerged from the present results: (a) Both contrast and induction occurred with the reinforcement rate held constant and a blackout between components, (b) induction was more common than contrast, (c) contrast occurred only in the presence of a stimulus different from that correlated with the punisher, and (d) contrast diminished with prolonged exposure to punishment. None of the current theoretical accounts of punishment contrast can explain the present results.     

Are there nontrivial constraints on colour categorization?

In this target article the following hypotheses are discussed: (1) Colour is autonomous: a perceptuolinguistic and behavioural universal. (2) It is completely described by three independent attributes: hue, brightness, and saturation: (3) Phenomenologically and psychophysically there are four unique hues: red, green, blue, and yellow; (4) The unique hues are underpinned by two opponent psychophysical and/or neuronal channels: red/green, blue/yellow. The relevant literature is reviewed. We conclude: (i) Psychophysics and neurophysiology fail to set nontrivial constraints on colour categorization. (ii) Linguistic evidence provides no grounds for the universality of basic colour categories. (iii) Neither the opponent hues red/green, blue/yellow nor hue, brightness, and saturation are intrinsic to a universal concept of colour. (iv) Colour is not autonomous.     

试答无法回答的问题

试答无法回答的问题让·多尔梅松著萧俊明译联合国教科文组织去年在巴黎以“我们不知道什么？”为主题召开了第一届哲学座谈会,取得了巨大的成功。《第欧根尼》第１６９期刊登了一些与会者的论文。第二届会议于１９９６年３月２７—３０日召开,讨论的问题如同前一届一样...     

State regulation of managed care: fragments of reform

State legislatures consider numerous bills to regulate managed care organizations. After identifying the legal, political, and economic barriers to state reform efforts, the paper assesses recent types of state regulation, particularly mandated benefits and disclosure requirements. Two prerequisites to future reform, coalition building and the diffusion of information about managed care, are analyzed.     

Variation of Isometric Response Force in the Rat

Hungry, unrestrained rats (N = 7) were rewarded for pressing a response beam in excess of 11 different force requirements. Changes in peak force production as a function of peak force requirement were examined by analyses of the first four moments of distributions of peak response forces: constant error, the within-subject standard deviation, skewness, and kurtosis. Results were similar to those previously obtained with human subjects: Constant error was positive at low and negative at high force requirements, the within-subject standard deviation increased as a negatively accelerating function of force requirement, and skewness and kurtosis were positive at low force requirements and decreased to negative values at the highest increments. Additional analyses of response kinetics indicated that rats, like humans, meet increasing force requirements by altering the rate of rise of force. The performance similarities suggest that common processes are engaged by the human and rat motor control systems to solve the problem of generating forces that are appropriate to the prevailing environmental constraints.