Influence of experience on postural control: effect of expertise in gymnastics

The authors investigated how expertise in motor skills that require fine postural control, such as gymnastics, influences postural regulation. Gymnasts and nongymnasts performed a postural stabilization task after anterior-posterior destabilization while looking at a target in front of them. The authors recorded and analyzed the center of pressure and the ankle, knee, and hip displacements. Gymnasts were able to react rapidly after destabilization to decrease their center of pressure and the angular movements. Moreover, they used their knees to stabilize posture, whereas the nongymnasts used their hips. These findings suggest that specific postural experience modifies the ability to coordinate and regulate posture. The authors discuss these results from an ecological perspective.     

Effect of arousal on internal clock speed in real action and mental imagery.

The possible implication of an internal clock as a mechanism accounting for the temporal homology between actual and mental walking is studied. To observe this phenomenon, stressful sound stimuli were used to increase arousal, which is known to activate the internal clock. Seventeen participants performed three tasks: (1) a time production task, used as a reference task reflecting the internal clock speed; (2) an actual walking task; and (3) a mental walking task, all three in two sound conditions (no noise and noise). The results showed a significant effect of arousal on time in each task. The effect of noise, increasing the arousal level, was greater in time production and mental imagery tasks than in real action. In addition, the percentages of change between the two sound conditions for actual and mental walking time were not statistically different. These findings are further evidence of the existence of a timing process common to actual and mental walking. The data are consistent with the implication of an internal clock in both actual and mental walking.     

Modulation of anticipatory postural adjustments in the anticipation-coincidence task

This study was designed to (a) verify whether the time available for movement preparation and execution modulates anticipatory postural adjustments/focal movement coordination and (b) determine to what extent the coordination in an anticipation-coincidence (AC) timing task is specific. Ten subjects performed an arm-raising movement from standing position in the reaction time, self-initiated (SI), and AC conditions. In the latter condition, subjects had to synchronize movement initiation or the end of the movement to the passage of a visual mobile on a target. In AC trials, time to contact (TC), which is the time before the mobile reached the target, was varied (720, 1,200, 3,000 ms). Electromyography, kinetic, and kinematics data were collected. Results showed that the coordination patterns were modified by TC, the velocity of the mobile, and the condition in which the movement was executed. It also showed that the behavior in the AC condition came closest to the 1 observed in SI condition when TC increased. These results support the existence of different control modes triggered by the temporal pressure.     

Relation between sport and spatial imagery: comparison of three groups of participants

The literature suggests that sport may be considered a spatial activity and that engaging in spatial activities increases the capacity of an individual to implement mental imagery. Moreover, mental rotation calls upon motor processes that are heavily involved in sporting activities. For these reasons, the authors hypothesized that athletes ought to perform mental rotation tasks better than nonathletes. Also, athletes trained to react quickly to constantly changing environments should be faster at processing the information in a mental rotation task than athletes operating in more settled environments. The results of this study show that athletes performed the mental rotation task significantly faster than nonathletes. These results support the suggestion that there is a link between sport and the ability to perform mental image transformations; however, this ability may not be specific to the conditions in which the athlete performs.     

An evaluation of stimulant medication on the reinforcing effects of play

Although a vast literature has indicated that stimulant medications are effective for reducing inappropriate behavior in children with attention deficit hyperactivity disorder (ADHD), the effects of stimulant medication on ancillary behaviors (e.g., play) have yet to be investigated with the same rigor. We used a reinforcer assessment procedure to evaluate the effects of medication on the play and social behavior of 5 preschool children who had been diagnosed with ADHD. Conditions included (a) social reinforcement (i.e., playing with friends), (b) alone play, and (c) quiet time (i.e., resting). Results indicated that 1 of the 5 participants selected fewer social reinforcers and more nonsocial reinforcers (alone play or quiet time) while on medication. The findings indicate that the reinforcer assessment procedure may be a viable way to evaluate medication effects on an ongoing basis and to inform treatment decisions.     

Sex bias in the newspaper treatment of male-centered and female-centered news stories

Differences in the newspaper treatment of men and women were examined in two sets of news stories collected a year apart, in the fall of 1976 and 1977. In both samples, coverage of women was more likely to include mention of personal appearance, marital status, and spouse than was coverage of men. These differences could not be attributed to the greater number of men in the news, nor to differences in the sections of the newspaper where stories about men and stories about women were usually found. They were equally true of locally written and national wire-service stories.