Effects of type of reinforcement on the intelligence test performance of retarded black children

This study examined the effects of different types of reinforcement on the performance of black males who had been diagnosed as being mildly mentally retarded, using the WISC-R. After each correct response, participants were given no reinforcement, a candy reward, traditional social reinforcement, or culturally relevant social reinforcement. Children given tangible or culturally relevant rewards obtained significantly higher scores than did children given either no reinforcement or traditional social reinforcement.     

Approximate solution (with error bounds) to a nonlinear,nonautonomous second-order differential equation

Two approximations are developed to the solution of an important nonlinear, nonautonomous second-order differential equation that arises in various fields of science and technology such as operations research, mathematical ecology and epidemiology. The origin of the second-order differential equation from a system of two nonlinear first-order differential equations modelling, for example, Lanchester-type combat between two homogeneous military forces is discussed. Extension of our results to a more general system of nonlinear first-order differential equations is indicated. Error bounds that do not require that the exact solution be known are developed. Some connections between our results and those for the Liouville-Green (or WKB) approximation to the solution of the linear second-order equation are indicated.     

A short form of the McCarthy scales of children's abilities: Methodological and clinical applications

The McCarthy Scales of Children's Abilities (MSCA) was administered to 50 kindergarten-aged children to obtain General Cognitive Indices (GCI). A short form of the MSCA was developed by using a step-wise regression analysis to select the six subtests that best predicted the GCI. The potential use of such a short form for kindergarten screening was discussed.     

Running performance in the heat is improved by similar magnitude with pre-exercise cold-water immersion and mid-exercise facial water spray

This investigation compared the effects of external pre-cooling and mid-exercise cooling methods on running time trial performance and associated physiological responses. Nine trained male runners completed familiarisation and three randomised 5 km running time trials on a non-motorised treadmill in the heat (33°C). The trials included pre-cooling by cold-water immersion (CWI), mid-exercise cooling by intermittent facial water spray (SPRAY), and a control of no cooling (CON). Temperature, cardiorespiratory, muscular activation, and perceptual responses were measured as well as blood concentrations of lactate and prolactin. Performance time was significantly faster with CWI (24.5 ± 2.8 min; P = 0.01) and SPRAY (24.6 ± 3.3 min; P = 0.01) compared to CON (25.2 ± 3.2 min). Both cooling strategies significantly (P < 0.05) reduced forehead temperatures and thermal sensation, and increased muscle activation. Only pre-cooling significantly lowered rectal temperature both pre-exercise (by 0.5 ± 0.3°C; P < 0.01) and throughout exercise, and reduced sweat rate (P < 0.05). Both cooling strategies improved performance by a similar magnitude, and are ergogenic for athletes. The observed physiological changes suggest some involvement of central and psychophysiological mechanisms of performance improvement.     

The impact phase of drop punt kicking for maximal distance and accuracy

Impact is an important aspect of the kicking skill. This study examined foot and ball motion during impact and compared distance and accuracy punt kicks. Two-dimensional high-speed video (4000 Hz) captured data of the shank, foot and ball through impact of 11 elite performers kicking for maximal distance and towards a target 20 m in distance. Four phases were identified during impact, with an overall reduction in foot velocity of 5.0 m · s^?1 (± 1.1 m · s^?1) and increase in ball velocity of 22.7 m · s^?1 (± 2.3 m · s^?1) from the start to end of contact. Higher foot velocity was found in distance compared to accuracy kicks (22.1 ± 1.6 m · s^?1 vs. 17.7 ± 0.9 m · s^?1, P < 0.05), and was considered to produce the significant differences in all impact characteristics excluding foot-to-ball speed ratio. Ankle motion differed between the kicking tasks; distance kicks were characterised by greater rigidity compared to accuracy kicks evident by larger force (834 ± 107 N vs. 588 ± 64 N) and smaller change in ankle angle (2.2 ± 3.3° vs. 7.2 ± 6.4°). Greater rigidity was obtained by altering the position of the ankle at impact start; distance kicks were characterised by greater plantarflexion (130.1 ± 5.8° vs. 123.0 ± 7.9°, P < 0.05), indicating rigidity maybe actively controlled for specific tasks.     

Preschool attendance and kindergarten readiness

Scores on the Georgia Kindergarten Assessment Program (GKAP) of 171 students (81 students who had attended preschool and 90 students who had not attended preschool) were analyzed to determine whether school readiness test performance was influenced by participation in preschool programs. Students who had attended preschool demonstrated statistically higher overall school readiness, higher Physical scores, and higher Personal scores than students who did not attend preschool. No difference, however, was found in GKAP scores as a function of type of preschool attended. Only one gender difference was revealed, that in the Social measure on the GKAP in which girls outperformed boys. Implications of our findings and suggestions for further research are discussed.