Effects of initial limb position on the accuracy, reaction time and electromyographic patterns of rapid movements

An experiment was performed to determine the effects of initial limb condition on final accuracy of rapid, elbow flexion movements in the horizontal plane. Electromyographic (EMG) recordings were also taken from an agonist (biceps) and antagonist (triceps) muscle by means of bipolar surface electrodes. In the experiment the subject's forearm was passively oscillated by means of an electric motor, and when an auditory buzzer sounded, the subject was required to react as quickly as possible and rapidly move to the previously learned target angle. Thus, movements could be initiated from either static or moving starting positions. The results indicated that general accuracy was not greatly affected by these manipulations, however, constant error and pre-motor reaction time suggested that subjects may have been utilizing initial limb condition information contrary to a mass-spring view. EMG data showed that the timing characteristics of the agonist and antagonist muscles were modulated, depending on the type of movement produced, supporting an impulse-timing model (Wallace 1981).     

Attention as a predictor of learning in infants

A total of 240 fourteen-week-olds were rewarded with a pattern of lights and tones for kicking. The reward display interrupted a background of random alternation between two lights and tones. In experiment 1, attention to this background stimulus during a 1-min baseline was assessed using the number of fixations of alternating lights. During 6 min of reward, high-attention subjects showed significantly greater changes in kicking rate from baseline than low-attention subjects. In experiment 2, the proportion of subjects with low attention ratings increased dramatically during an extended 5-min baseline period, and those subjects with low attention ratings at the end of baseline did not show an increase in kicking from baseline to the reward phase, while high-attention subjects did show evidence of learning. Thus, an objective measure of attention, empirically separate from the dependent learning measure, provided a significant prediction of the effectiveness of subsequent reinforcement, and could be manipulated simply by extending the baseline by as little as 4 min.     

Cognition in music

A cognitive/constructive view of music is put forth that diverges from traditional conceptions of music (e.g., music as sound; music as behavior; music as communication). The present view attempts to be compatible with the evidence of historic style changes that have occurred in the notated repertory of Western music. Two levels of cognitive processing are proposed: processes on the level of particular styles (germane to a certain period, culture, or community) and processes that are generic, universal, or cross-stylistic. Twelve such generic processes are described in detail. Several problems in the research stemming from earlier definitions of music are explored. In particular, attention is given to the artifacts of theoretical analysis (e.g., scales, chords, and discrete pitches) and their influence on music-psychological research.     

The long-term outcome of a personal network-oriented HIV prevention intervention for injection drug users: The SAFE study

Social influence processes have been found to affect numerous drug and health-related behaviors. We postulated that by using a network-oriented intervention it may be possible to capitalize on social influence processes to reduce human immunodeficiency virus (HIV) risk behaviors. The present study used an experimental study design for delivering a psychoeducational acquired immunodeficiency syndrome (AIDS) preventive intervention to injection drug sharing networks. Participants were recruited from the ALIVE study, an epidemiological study in Baltimore. In the present paper we examine the self-reported behavioral outcomes of 117 injection drug users 18 months after the baseline interview. HIV seronegative experimental participants reported significantly less frequent needle sharing and less injecting of heroin and cocaine than controls. In multiple logistic regression models of HIV seronegative participants, there was a significant negative association between assignment to the experimental group and the HIV-related behaviors of needle sharing and sharing of cookers in the prior 6 months; controls were 2.8 times more likely than experimentals to report needle sharing and were 2.7 times more likely to report sharing cookers. The results of this 18-month follow-up suggest that among injection drug users network-oriented interventions may be a promising approach to HIV prevention.     

Emotional expressions of female and male infants in a social and a nonsocial context

While observational studies of the emotional expressions of women and men have revealed several consistent patterns of gender differences, data pertaining to the emotional expressions of male and female infants are largely inconsistent. Attempting to trace the course of early emotional development in female and male infants, we undertook to compare the emotional expressions of boys and girls at 2 1/2 and 5 months of age in a variety of situations. All infants who participated in the study were from French-speaking Caucasian families of low and middle class. At each age level, infants were observed in a social and nonsocial situation. The social situation began with a mother—infant interaction, followed by a period during which the mother remained silent and still-faced. In the nonsocial situation, a mobile was presented and then removed. Infants' facial expressions were coded using the AFFEX system. Direction of gaze was also coded. Overall, boys' and girls' reactions were quite similar. At both ages, male and female infants spent more time looking at the toy than at their mother and showed more expressions of interest toward the toy. They also smiled more while interacting with their mother and displayed more negative expressions when facing their still-faced mother. One gender difference was found: At 2 1/2 months, girls smiled more than boys while interacting with their mother. Several explanations are proposed to account for these findings.     

Effects of movement duration and visual feedback on visual and proprioceptive components of prism adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement ever 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of the movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.     

Distressed and nondistressed third- and sixth-grade children's self-reports of life events and impact and concordance with mothers

This study examined the concordance of third- and Sixth-grade distressed and nondistressed children's self-reports of the occurrence and perceived impact of life events that had occurred during the preceding 12 months with their mothers' perceptions. The study also examined whether maternal self-reports of dysphoria affects concordance between mother/child dyads on children's self-reports of occurrence and perceived impact of life events. Eighty-eight mother/child dyads, matched on Children's Depression Inventory scores, grade, sex, race, and school were included. Results indicated that distressed children endorsed more items on the Coddington Life Events Record (LER), and perceived them more negatively, than nondistressed children. Small, but statistically significant concordance rates were found between dyads on the occurrence of life events and the perceived impact of these events: Distressed children and their mothers had more mutually endorsed items than nondistressed children and mothers, and third-grade children had higher concordance rates with their mothers when compared to sixth-grade children. Third-grade children also appeared to commit more errors of commission on the LER. Finally, Maternal distress mediated mother/child concordance. Possible explanations for these results and future research directions are discussed.     

The Occupational Stereotypes and Expectations for Their Children Held by Mothers Representing Different Ethnic Communities in Miami1

The study focuses on the occupational expectations and aspirations that mothers, representing 5 different ethnic groups and 2 social classes, have for their children. An intergroup perspective was adopted by considering the occupational stereotypes that mothers have of the different ethnic groups, and the extent to which ethnic group membership influences hiring decisions. The results indicate that there exist very clear ethno-occupational stereotypes, and that these influence hiring decisions. However, despite wide variation in the occupational status in the stereotypes of different ethnic groups, mothers had universally high expectations for their children. The extent to which these represent optimism or false hope is addressed.     

TEACHING SOCIAL SKILLS TO STUDENTS WITH AUTISM TO INCREASE PEER INTERACTIONS IN AN INTEGRATED FIRST-GRADE CLASSROOM

We investigated the use of social skills groups to facilitate increased social interactions for students with autism and their nonhandicapped peers in an integrated first-grade classroom. Social skills groups consisted of training students and peers in initiating, responding, and keeping interactions going; greeting others and conversing on a variety of topics; giving and accepting compliments; taking turns and sharing; asking for help and helping others; and including others in activities. Training occurred during the first 10 min of 20-min play groups, four times per week. Using a multiple baseline across subjects design, results demonstrated increases in the frequency of, time engaged in, and duration of social interactions, as well as the responsivity of students and peers to each other. Results were maintained when students were monitored and given feedback on social performance in play groups and during follow-up.