Objective: The goal of this research is to attest Covert Repair Hypothesis (CRH) i.e, discovering the phonological loop of the word production process in stuttering children.

Materials & Methods: In this analytical (Case – Control) research, forty bisyllabic and trisyllabic nonwords were designed. After the pilot study, these nonwords were presented to twelve stuttering children with the ages 5-8 and twelve nonstuttering children by the use of DMDX software. Children were asked to repeat the nonwords immediately after hearing them, the reaction time were recorded by the DMDX. The number of phonological errors and correct responses were determined.

Results: Findings proved that stuttering children in all its forms except of reaction time of trisyllabic nonwords had a weak performance. However, the research results were not statistically significant.

Conclusion: The study evidences show differences between stuttering and nonstuttering children performances. This may outline the possible of defect in language processes of stuttering children, especially in phonological encoding of word production mechanism. Also, the difference pattern between groups had coordination with CRH assumptions.

Objective: The aim of this research is study of explicit learning in unilateral stroke patients and comparison with normal individuals and identify effects of age, sex and study level in this motor learning.

Materials & Methods: In this case–control analytical research we used a software for studying motor learning. In this software 4 squares with different colors were appeared on the monitor and individuals should press a defined key immediately after observing it. 15 patients and 15normal matched were participate in this research. In first day individuals practiced 8 motor block (4 regular blocks, then 2 blocks in randomed manner and finally 2 regular blocks). Next day individuals practiced a retention test consist of 2 regular block. Befor starting test, individuals took complete explanation about sequence of squares. All individuals were right handed and impaired hand in patients was right side and patients practiced with impaired hand. Motor sequences and blocks were recorded with software. Data was analyzed by using Chi-square test, T-test for independent groups and ANOVA.

Results: This research revealed that performance of patients was slower than normal group (P<0/05). Difference of performance speed of men and women in normal and patient group was not significant. Age, sex and study level was not effective on research results (P>0/05). Block times were decreased from second to fourth block and time differences between second block with eight and tenth block (next day) were significant in both patient and normal groups (P<0/05).

Conclusion: Although performance of unilateral stroke patients was slower than normal individuals, motor learning (stable decrease of block times) was similar. On the other hand in patients with unilateral stroke ability of motor learning with affected hand was preserved.

Objective: This research was aimed at investigating the theory of multiple resources and central resource of attention on secondary task performance of talking with two types of cell phone during driving.

Materials & Methods: Using disposal sampling, 25 male participants were selected and their reaction to auditory stimulus in three different driving conditions (no conversation with phone, conversation with handheld phone and hands-free phone) were recorded. Driving conditions have been changed from a participant to another participant in order to control the sequence of tests and participants familiarity with the test conditions.

Results: the results of data analysis with descriptive statistics and Mauchly’s Test of Sphericity, One- factor repeated measures ANOVA and Paired-Samples T test showed that different driving conditions can affect the reaction time (P<0/001). Conversation with a handheld phone increases drivers’ simple reaction time to simple auditory stimulus (P>0.001). Phone Conversation with hands-free phone increases drivers’ simple reaction time to auditory stimulus (P<0.001). Using handheld phone does not increase drivers’ reaction time to auditory stimulus over hands-free phone (P<0.001).

Conclusion: The results confirmed that the performance quality of dual tasks and multiple tasks can be predicted by Four-dimensional multiple resources model of attention and all traffic laws in connection with the handheld phone also have to be spread to the use of hands-free phone.

Objective: The purpose of this study was studying of explicit motor learning in Relapse-Remission (RR) MS patients and compare with healthy subject.

Materials & Methods: A serial reaction time task by using software was applied for studying explicit motor learning in 15 RRMS patients and 15 matched healthy subjects. In this task four squares with different colors appeared on the computer screen and the subjects were asked to press 1 of 4 keys corresponding to the appropriately colored square immediately after observing it. In the first day subjects practiced 8 motor blocks with a retention test consisted of 2 patterned blocks, 48 hours later. Before test, the subjects were told the order of random and patterned blocks, and then RT values were calculated for each block and K-S test, paired T test and independent-samples t-test were used to analyse the measured blocks times.

Results: The patient groups performed this task slower than healthy groups (P<0.05). Blocks time difference between the first block and tenth block, were significant in both groups (P<0.05). But Explicit motor learning in healthy subjects was higher than patient groups (P<0.05).

Conclusion: Although patient groups performed this task slower than healthy subjects, there was motor learning in RRMS patient but this explicit motor learning was less than healthy matched subjects.

Objective: Normal breathing is essential for adjustment of natural metabolism of human body. Therefore, the aim of this study was to evaluate the control of breathing pattern in normal subjects both at rest and during cognitive loading.

Materials & Methods: In this quasi-experimental study, 24 healthy subjects (14 males, 10 females) were selected by simple and convenient sampling. Spirometry data including inspiration and expiration times, total time of respiration, tidal volume, minute ventilation, respiratory rate, inspiratory-total time ratio, and capnography data containing end tidal CO2 were obtained from all participants in two conditions: with or without cognitive loading.

Results: Mean of end tidal CO2 in expiration, inspiration times and total duration of respiration in rest condition was significantly larger than those of during cognitive loading. There was also a medium direct correlation between tidal volume, inspiration and expiration times, total duration of respiration and inspiratory-total time ratio and end tidal CO2.

Conclusion: Cognitive loading has an inevitable effect on breathing pattern. There is also good correlation between breathing pattern and biochemical breathing of metabolic outcomes.

Objective Individuals performance at the workplace is affected by different adopted postures. Sitting postures are mostly used during office work. Improper sitting postures may cause muscle fatigue and discomfort in the spine and also result in mental workload. Poor posture may result in human errors and delay in information processing. Previous studies have demonstrated the relationship between static sitting postures and cognitive factors such as reaction time to an auditory stimulus. Also, some recent studies have demonstrated the effect of static postures on cognitive performance. To our knowledge, none of the studies had considered the sitting and standing postures effects on cognitive performance simultaneously. The aim of this study was to evaluate cognitive performance during three different static working postures: standard sitting, standing, and self-selected sitting postures.
Materials & Methods This semi-experimental design study was conducted on the twenty-nine healthy students (aged 20-30 years). The non-probability sampling method was selected. All participants provided their written informed consent. Participants with no musculoskeletal disorders, heart disease, spine surgery, and history of depression and stress were selected. Their depression status and level of stress were measured using Beck questionnaire. The study was approved by the Ethics Committee of University of Social Welfare and Rehabilitation Sciences. Subjects performed complex Stroop test and typing activity in an office-like laboratory setting at the University of Social Welfare and Rehabilitation Sciences. Stroop test lasted about 9-12 minutes, and a typing task was also designed for approximately 5 minutes for all subjects. Three random postures were selected based on common postures used in the office. The effects of the postures (standard standing, standard sitting, and self-selected sitting posture) on dependent variables such as total test duration and reaction time to congruent and incongruent stimulus, number of typing words and number of typing error were assessed with Repeated Measures ANOVA. To examine the differences between groups, the paired t-test was used.
Results The results demonstrated that reaction time measure and number of typing error (accuracy) were affected by postures (P=0.001). Post hoc analysis demonstrated that reaction time was significantly different between self-selected sitting posture and standard sitting posture (P=0.001), self-selected sitting posture and standard standing posture (P=0.043), standard sitting posture and standard standing posture (P=0.001). With considering the average amount of reaction time to congruent and incongruent cases, it was observed that there is less reaction time in the standardized sitting posture (M=628.67 ms) compared to the self-selected sitting posture (M=689.41 ms) and standard standing posture (M= 675.16 ms). Also, among the three postures studied a significant difference was observed in the number of typing error words (P=0.001). The number of typing error (accuracy) was lower in this posture compared to the two other postures (M=1.58).
Conclusion This study demonstrates that cognitive performance is affected by working postures. This study demonstrates that standard sitting posture is the best posture. Therefore, it is recommended that sitting posture can help in increasing cognitive performance in the workplace.