Shaghayegh Mohammadi; Hamid Salehi
Abstract
The purpose of this investigation was to examine the anticipation of taekwondo athletes when facing right- and left-footed kicks. Expert taekwondo athletes (n = 40; age = 20.935.12 years; Taekwondo Kyorugi competition experience = 7.584.49years) were shown identical video simulations of right-footed ...
Read More
The purpose of this investigation was to examine the anticipation of taekwondo athletes when facing right- and left-footed kicks. Expert taekwondo athletes (n = 40; age = 20.935.12 years; Taekwondo Kyorugi competition experience = 7.584.49years) were shown identical video simulations of right-footed and left-footed chagi kicks. The videos were temporally paused at five different time occlusion points from the start to the end of the kicks. The participants were required to make prediction of kick types (front vs. back leg to head or trunk of opponent in kick attacks). The results indicated that anticipation of right-footed kicks was significantly more accurate than that of left-footed kicks. The footedness effect was found to be most pronounced when kicks videos were paused at 120 ms prior to the kick completion. Thus, the opponent’s footedness seems to affect visual anticipation of the type of an action. Mean percentages of correct predictions suggest that kyorugi taekwondo players may not adopt an optimal visual search strategy when facing left-footed kicks, resulting in fails in the detection of anticipation-relevant kinematic cues before the end of left-footed kicks in most instances (i.e., about 120 ms and more before the kick completion). It seems that the lower ability of recognizing the type of left- vs. right-footed opponents' kicks were due to the observers’ reduced perceptual awareness with left-footed actions
Hamid Salehi; Zahra Zareie; Parisa Kalantari
Abstract
The main aim of the present study was to investigate whether the goalkeepers’ postures that mimic the Müller–Lyer illusion can influence penalty-takers’ perceptions and the location of throws. A representation of a goalkeeper was projected onto a blank screen (without goalposts ...
Read More
The main aim of the present study was to investigate whether the goalkeepers’ postures that mimic the Müller–Lyer illusion can influence penalty-takers’ perceptions and the location of throws. A representation of a goalkeeper was projected onto a blank screen (without goalposts and crossbar). The goalkeeper was displayed in arms-up (45 degrees above horizon), arms-out (horizontal, as control), and arms-down (45 degrees below horizon) postures. Participants (11 young male handball players) performed two tasks. They stood in front of the screen at a distance of 5 m and observed the goalkeeper displayed in one of the three postures. The participants were asked either to throw a tennis ball, or aim a laser pointer at, the horizontal position of the goalkeeper’s hand. The horizontal distances of throwing and aiming locations were measured from the midline of the body of the goalkeeper model. The goalkeeper postures affected the locations of the throwing and aiming. The participants’ aiming and throwing tasks were found to be significantly farther from and closer in the arms-up and arms-down postures compared with the arms-out posture respectively. The experiment demonstrated that a goalkeeper adopting Müller–Lyer postures can influence his opponent’s perception of maximum reach and his motor behavior.
Hamid Salehi; Mahboubeh Mehrvarz; Mehdi Rafaei
Abstract
The aim of this study was to determine if the reduction of errors during practice facilitates implicit motor learning processes in children. 30 children (meanage =11.33±1.32 yr) threw beanbags with a near-to-far or a far-to-near order, while their vision was occluded. The near-to-far group ...
Read More
The aim of this study was to determine if the reduction of errors during practice facilitates implicit motor learning processes in children. 30 children (meanage =11.33±1.32 yr) threw beanbags with a near-to-far or a far-to-near order, while their vision was occluded. The near-to-far group began the acquisition phase at a distance of 2 m from the target. Then, they practiced the task at a distance of 3 m, 4 m and finally 5 m from the target. Far-to-near group began the practice phase at the distance of 5 m and then moved to 4 m, 3 m and 2 m respectively. Delayed single-task and dual-task tests were administered at a distance of 3.50 m from the target. During the acquisition phase, the ratio of errors made by the near-to-far (errorless) group was found to be significantly less than the far-to-near (errorful) group. No significant intergroup difference was found in the single-task test. The results also revealed that the errorless group performed the task with less errors than the errorful group in the dual-task condition. It was generally concluded that less errors during practicing a motor skill can facilitate the use of implicit motor learning processes in children.
Hamid Salehi; Somayeh Shahdousti; Mehdi Rafaei Boroujeni; Maryam Nezakatalhosaini
Abstract
To create more efficient learning environments, the learner’s role and his/her influence on the learning process should be considered. The aim of this study was to determine the way self-controlled practice affected performance and learning of motor patterns. 60 female undergraduate students (mean ...
Read More
To create more efficient learning environments, the learner’s role and his/her influence on the learning process should be considered. The aim of this study was to determine the way self-controlled practice affected performance and learning of motor patterns. 60 female undergraduate students (mean age = 20.73 yr., SD = 2.98) were randomly assigned to four groups that ordered self-controlled practice or three yoked-to-self-controlled. In the acquisition phase, the self-controlled group was told they could choose whichever of three motor patterns they wanted before they practiced each trial. Each self-controlled participant’s practice schedule was served as the predetermined practice schedule for each corresponding participant in the yoked control groups. The yoked control participants practiced the tasks with high, low, or no (classic yoked-control) variability. The results showed that the self-controlled group performed the tasks faster than the other yoked control groups in both the acquisition phase and the retention tests. The findings suggest that if the learners are allowed to choose the sequence of practice in multiple motor skills, this would have facilitating effects on their performance and motor learning.
Hamid Salehi; Zahra Zamanpour Boroujeni
Abstract
This study examined the effects of practice scheduling and attentional focus on learning a sport skill. 40 female high school students (mean age = 16.02 ± 0.88 years) practiced dart-throwing skill under either blocked or random practice schedules while their attention was directed ...
Read More
This study examined the effects of practice scheduling and attentional focus on learning a sport skill. 40 female high school students (mean age = 16.02 ± 0.88 years) practiced dart-throwing skill under either blocked or random practice schedules while their attention was directed to either the skill (dart scores) or an irrelevant cue (auditory tones) using dual-tasks. Analysis of variance were conducted at baseline, practice phase and a delayed transfer test. Results demonstrated a significant score improvement from baseline to delayed transfer test for all groups. Furthermore, the greatest improvement from baseline to delayed transfer test was observed in random-irrelevant condition compared with the other conditions. In conclusion, the current study provided new information about the interactive relationship between practice scheduling and attentional focus during learning a sport skill.
Hamid Salehi; Mahshid Zarezade
Abstract
Fundamental movement skills are observable patterns of motor behaviors including locomotor, manipulative, and stability activities. The aim of this study was to assess the gross motor development and the movement skill proficiency in elementary school children in Tehran city. The test of Gross ...
Read More
Fundamental movement skills are observable patterns of motor behaviors including locomotor, manipulative, and stability activities. The aim of this study was to assess the gross motor development and the movement skill proficiency in elementary school children in Tehran city. The test of Gross Motor Development-2 (Ulrich, 2000) was administered to 712 children aged between 7 and 11. Performance of each 12 gross motor skills was assessed qualitatively. The percentages of poor/professional and nearly professional (advanced) children were reported by gender and age group. The assessments indicated that the highest percentages of advance level for both genders belonged to sliding and running, but these proportions were generally low in other skills. The percentages of advanced boys were statistically more than the percentages of girls in one locomotor skill (leaping) and two object-control skills (kicking and striking). In three object-control skills (dribbling, kicking and throwing), the percentages of the older advanced children were statistically more than younger ones. It was suggested that more attention should be paid to promote movement skill proficiency in elementary schools.
Farhang Yazdanparast; Hamid Salehi; Shahram Lenjannejadian
Abstract
Pressure refers to the feelings an athlete has about performing in a competitive situation. The primary aim of this study was to examine kinematic changes of tennis serves in increasing competitive pressure. 20 semi-professional right-handed male tennis players completed 120 serves under low (normal) ...
Read More
Pressure refers to the feelings an athlete has about performing in a competitive situation. The primary aim of this study was to examine kinematic changes of tennis serves in increasing competitive pressure. 20 semi-professional right-handed male tennis players completed 120 serves under low (normal) and high competitive pressure phases. Pressure checks (heart rate and perceived competitive state anxiety) were administered before serves in the low and the high-pressure phases. Performance and kinematic parameters of the serves (two-dimensional motion analysis) were also measured. The pressure manipulation showed a significant increase in the heart rate and perceived pressure from the low pressure to the high pressure (P<0.001). Decreased performance showed that the choking effect under pressure was observed (P<0.001). Results showed that the height of serves significantly decreased under pressure (P<0.001), while the ball speed remained unchanged (P>0.05). This study explained performance changes under competitive pressure using kinematic factors.
