22474
« on: June 06, 2009, 02:00:01 am »
High versus low contextual interference in simulation-based training of troubleshooting skills: effects on transfer performance and invested mental effort
The effects of contextual interference on practice behavior, transfer performance, and cognitive load for learning troubleshooting skills were studied. A low contextual interference (LCI) condition, in which subjects practiced to diagnose system failures in a blocked schedule, was compared with a high contextual interference (HCI) condition, in which failures were practiced in a random schedule. The following hypotheses are stated. Hypothesis 1: during practice, subjects in the HCI group will require more time to reach a high performance level (i.e., more accurate and/or faster diagnoses of system failures) on practice problems and will have to invest more mental effort relative to subjects in the LCI group. Hypothesis 2: subjects in the HCI group will show higher performance and lower invested mental effort on far transfer test problems, relative to subjects in the LCI group, but there will be no difference between the groups on near transfer test problems. The results showed that subjects in the HCI group were more accurate in diagnosing far transfer problems, although during practice they needed more time to diagnose system failures and made significantly more incorrect diagnoses.
Contextual Interference Effects on the Acquisition, Retention, and Transfer of a Motor Skill.
Retention and transfer of motor tasks was greater for high interference (random) acquisition groups than for low interference (blocked) acquisition groups. This effect was most notable when transfer was measured for the transfer task of greatest complexity. Results support Battig's conceptualization of contextual interference effects on retention and transfer. (Author/CP)
Contextual interference effects with skilled baseball players.
Department of Physical Education and Kinesiology, California Polytechnic State University, San Luis Obispo 93407.
The learning benefits of contextual interference have been frequently demonstrated in different settings using novice learners. The purpose of the present study was to test such effects with skilled athletic performers. Scheduling differences for biweekly additional ("extra") batting-practice sessions of a collegiate baseball team were examined. 30 players (ns = 10) were blocked on skill and then randomly assigned to one of three groups. The random and blocked groups received 2 additional batting-practice sessions each week for 6 wk. (12 sessions), while the control group received no additional practice. The extra sessions consisted of 45 pitches, 15 fastballs, 15 curveballs, and 15 change-up pitches. The random group received these pitches in a random order, while the blocked group received all 15 of one type, then 15 of the next type, and finally 15 of the last type of pitch in a blocked fashion. All subjects received a pretest of 45 randomly presented pitches of the three varieties. After 6 wk. of extra batting practice, all subjects received two transfer tests, each of 45 trials; one was presented randomly and one blocked. The transfer tests were counterbalanced across subjects. Pretest analysis showed no significant differences among groups. On both the random and blocked transfer tests, however, the random group performed with reliably higher scores than the blocked group, who performed better than the control group. When comparing the pretest to the random transfer test, the random group improved 56.7%, the blocked group 24.8%, and the control group only 6.2%.(ABSTRACT TRUNCATED AT 250 WORDS)
Muscular coactivation The role of the antagonist musculature in maintaining knee stability
The objective of this study was to quantify the coacti vation patterns of the knee flexor and extensor muscles as part of continued efforts to identify the role of the antagonist muscles in maintaining joint stability.
The simultaneous EMG from the flexor and extensor muscles of the knee were recorded during maximal effort, slow isokinetic contractions (15 deg/sec) on the plane parallel to the ground to eliminate the effect of gravity. The processed EMG from the antagonist mus cle was normalized with respect to its EMG as agonist at maximal effort for each joint angle. The plots of normalized antagonist EMG versus joint angle for each muscle group were shown to relate inversely to their moment arm variations over the joint range of motion. Additional calculations demonstrated that the antago nist exerts nearly constant opposing torque throughout joint range of motion. Comparison of data recorded from normal healthy subjects with that of high perform ance athletes with hypertrophied quadriceps demon strated strong inhibitory effects on the hamstrings coac tivations. Athletes who routinely exercise their ham strings, however, had a coactivation response similar to that of normal subjects.
We concluded that coactivation of the antagonist is necessary to aid the ligaments in maintaining joint stability, equalizing the articular surface pressure dis tribution, and regulating the joint's mechanical imped ance. The reduced coactivation pattern of the unexer cised antagonist to a hypertrophied muscle increases the risk of ligamentous damage, as well as demon strates the adaptive properties of the antagonist muscle in response to exercise. It was also concluded that reduced risk of knee injuries in high performance ath letes with muscular imbalance could result from com plementary resistive exercise of the antagonist muscle.
Show Posts
