What does being initiated severely into a group do? The role of rewards

Undergoing an admission process (an initiation) can induce exaggerated feelings about a group, but there is little research about the role of rewards. This study replicated Aronson and Mills’ (1959) experiment. Seventy participants underwent either a severe initiation or a mild initiation. After the initiation, about half the sample received an extrinsic reward for merely completing the task. The remaining half did not receive an extrinsic reward. This was to vary the amount of dissonance. Initiation severity and reward condition had significant, noncrossing interactions. A reward led to higher group identity than no reward, supporting Levine and Moreland's (1994) group socialization model. A severe initiation did not lead to more group identity than a mild initiation; therefore, Aronson and Mills’ findings were not replicated. Interestingly, a mild initiation followed by a reward led to more group identity than a severe initiation followed by a reward. Another unexpected finding was that the extrinsic reward made no difference to group identity if the initiation was severe. Effects on ratings of the discussion were nonsignificant. Future research needs to establish how new group members ponder the severity of the admission process during the cost–benefit calculation preceding their identification with a group.     

Processes of anticipatory postural adjustment and step movement of gait initiation

The purpose of this study was to elucidate whether the anticipatory postural adjustment (APA) and focal step movement of gait initiation are produced as a single process or different processes and whether the APA receives an inhibitory drive from the ongoing stop process of gait initiation. Healthy humans initiated gait in response to a first visual cue that instructed the initial swing leg. In some trials, a switch or stop cue was also provided after the first cue. When the stop cue was provided, participants withheld gait initiation. When the switch cue was provided, participants immediately switched the initial swing leg. In both the stop and switch tasks, the APA in response to the first cue, represented by the S1 period of the displacement of the center of pressure, appeared in more than half of the trials in which the withholding of gait initiation or switching of the initial swing leg was successfully completed. These findings indicate that the APA and focal step movement of gait initiation are produced as a dual process. In trials in which the APA in response to the first cue appeared, the amplitude and duration of the APA were decreased when the participants switched the initial swing leg or withheld gait initiation. This finding indicates that the ongoing stop process of gait initiation produces an inhibitory drive over the APA. The decreases in the amplitude and duration of the APA during the switching of the initial swing leg were similar to those during the withholding of gait initiation; moreover, the decreases during the switching of the initial swing leg were positively correlated with the decreases during the withholding of gait initiation. Thus, the stop processes during switching the initial swing leg and withholding gait initiation likely share a common inhibitory mechanism over the APA.     

CD_4~+ CD_(25)~+调节性T细胞在妊娠与分娩中的作用

近代生殖免疫学研究认为,正常妊娠维持有赖于母胎免疫耐受的形成,耐受一旦失调,就可能妊娠失败,发生如流产,妊娠期高血压疾病,胎膜早破,分娩发动等。近几年来,国内外学者逐渐认识到CD4+CD25+调节性T细胞在妊娠中的重要作用并进行系列研究。本文就目前CD4+CD25+调节性T细胞在妊娠与分娩中的作用作一综述。     

The Relation Between Childhood Proactive and Reactive Aggression and Substance Use Initiation

The current study examined whether proactive and reactive aggression were associated with the risk for initiation of substance use from fourth to ninth grade in a sample of 126 aggressive children (66% male). In addition, the study examined whether these functions of aggression increased risk for initiation via peer delinquency and peer rejection. Proactive aggression was marginally significantly directly associated with risk for initiation of alcohol use and indirectly associated with risk for initiation of marijuana and tobacco use through peer delinquency. Reactive aggression was associated with increased risk for initiation of tobacco and marijuana use through a complex chain that included both peer rejection and peer delinquency. However, high levels of reactive aggression that did not lead to peer rejection were negatively associated with risk for initiation of tobacco and marijuana use. Implications for intervention are discussed.

The intergenerational transmission of implicit and explicit attitudes toward smoking: Predicting adolescent smoking initiation

This study examined the intergenerational transmission of implicit and explicit attitudes toward smoking, as well as the role of these attitudes in adolescents’ smoking initiation. There was evidence of intergenerational transmission of implicit attitudes. Mothers who had more positive implicit attitudes had children with more positive implicit attitudes. In turn, these positive implicit attitudes of adolescents predicted their smoking initiation 18-months later. Moreover, these effects were obtained above and beyond the effects of explicit attitudes. These findings provide the first evidence that the intergenerational transmission of implicit cognition may play a role in the intergenerational transmission of an addictive behavior.     

DEFINING CHILD NONCOMPLIANCE: AN EXAMINATION OF TEMPORAL PARAMETERS

This study examined compliance parameters for 53 clinic-referred and nonreferred children, ages 2 to 10 years. Although there were significant differences between the referred and nonreferred samples for percentage compliance, there were no significant differences between the referred and nonreferred samples in terms of initiation or completion latencies. The average initiation latency was 5.92 s, whereas 98% of the sample initiated compliance within 14 s. Younger children did take longer to complete tasks. Results suggest that the use of short latencies in defining noncompliance may represent overly conservative criteria.     

Control of Gait Initiation

The initiation of gait from a standing posture by 6 subjects, who took controlled-length steps, was analyzed. Using an inverted-pendulum model, we found that the duration of gait initiation was independent of gait velocity. This finding suggests that subjects' biomechanical constants are the determining factors for initiating movement. Both the instantaneous velocity of the center of gravity at the end of the first step (resulting in the propulsive forces measured on the ground) and the steady-state velocity (resulting in the step length and frequency) varied with step length, whereas step frequency did not. But step frequency and progression velocity were linked, for step frequency always increased in parallel with increased progression velocity. We interpret the correlation between velocity and frequency variations to be a peripheral expression of the posturodynamic control of the step parameters by the progression forces.     

Elucidating satisfaction with physical activity: An examination of the day-to-day associations between experiences with physical activity and satisfaction during physical activity initiation

Satisfaction with physical activity is known to be an important factor in physical activity maintenance, but the factors that influence satisfaction are not well understood. The purpose of this study was to elucidate how ongoing experiences with recently initiated physical activity are associated with satisfaction. Participants (n?=?116) included insufficiently active volunteers who initiated a self-directed physical activity regimen and completed daily diaries about their experiences for 28?days. We used multilevel models to examine the associations between experiences with physical activity and satisfaction. Significant between-person effects demonstrated that people reporting higher average levels of positive experiences and lower levels of thinking about the negative aspects of exercise were more likely to report higher levels of satisfaction (ps?<?.05). Positive experiences and perceived progress toward goals had significant within-person effects (ps?<?.01), suggesting that day-to-day fluctuations in these experiences were associated with changes in satisfaction. These findings elucidate a process through which people may determine their satisfaction with physical activity.     

Monaural Auditory Cue Affects the Process of Choosing the Initial Swing Leg in Gait Initiation

The authors investigated the effect of an auditory cue on the choice of the initial swing leg in gait initiation. Healthy humans initiated a gait in response to a monaural or binaural auditory cue. When the auditory cue was given in the ear ipsilateral to the preferred leg side, the participants consistently initiated their gait with the preferred leg. In the session in which the side of the monaural auditory cue was altered trial by trial randomly, the probability of initiating the gait with the nonpreferred leg increased when the auditory cue was given in the ear contralateral to the preferred leg side. The probability of choosing the nonpreferred leg did not increase significantly when the auditory cue was given in the ear contralateral to the preferred leg side in the session in which the auditory cue was constantly given in the ear contralateral to the preferred leg side. The reaction time of anticipatory postural adjustment was shortened, but the probability of choosing the nonpreferred leg was not significantly increased when the gait was initiated in response to a binaural auditory cue. An auditory cue in the ear contralateral to the preferred leg side weakens the preference for choosing the preferred leg as the initial swing leg in gait initiation when the side of the auditory cue is unpredictable.     

A Note on Motor Learning Without Post-Response Knowledge of Results

The authors studied the adjustment of the 2 distinct known expressions of gait velocity, the velocity of the center of gravity (CG) and the velocity of the center of foot pressure (CP) at the end of the 1st step in 2 experimental situations: natural gait initiation (the control situation, CS) and heel-off gait initiation (the test situation, TS). Gait was initiated by 7 healthy participants, from an erect spontaneous posture in the CS and from a posture with heels raised in the TS, on a force platform at 3 self-selected speed conditions. Biomechanical data from the force platform were collected in both experimental situations, and the authors used a particular gait analysis based on the differential method of Y. Brenière (2003) in order to approach velocity modulation by means of step length and frequency. Results showed that CG and CP velocities were adjusted differently during heel-off gait initiation than during natural gait initiation. CP velocity, as compared with CG velocity, was overestimated in TS. Results also established the relevance of the expression of step velocity by means of step length and frequency: The central nervous system, taking into account the specific postural constraints of each experimental situation, uses a reference value and a regulating parameter to modulate step velocity. Moreover, the contributions of 1st step length and frequency to the expression of step velocity in TS and CS were different. Thus, a specific locomotor behavior corresponds to a given experimental situation that is characterized by its own initial biomechanical constraints.