فصلنامه تازه های علوم شناختی
سال هفدهم شماره 2 (پیاپی 66، تابستان 1394)

This study was designed to investigate the effect of mental fatigue on response-time and error-rate of cyclic tasks using a simulated model in ACT-R cognitive architecture. The effects of fatigue on cyclic tasks with high frequency and long duration have not thus far been systematically studied. In the present study، an unvarying cyclic task was modeled in ACT-R (Adaptive Control of Thought-Rational) environment. For each run، the average response-time per cycle and total error-rate were obtained through dividing the total working time and total number of incorrect responses، respectively by the total number of cycles after eliminating the learning phase. Then، the effect of mental fatigue was studied in the cognitive architecture and a fatigue-based multiplier was incorporated into the model. This multiplier was a concentration index which was declined when response-time and error-rate increased. Next، real data were collected through experiments on volunteers and compared with simulated results using analysis of variance (ANOVA). After validation of the model، the impact of fatigue-based multipliers on the response-time and error-rate were analyzed for different iteration numbers. Using an F test at α=0. 05، no significant disagreement between virtual and real data and the validity of the model was shown. Final results for 3-sec cycle tests revealed up to 0. 5 sec increase in the average response-time for each cycle and 12% in the average error-rate. After 1000 iterations of the sample task، the average response-time for each cycle and the average error-rate are increased by 0. 43 sec and 8%، respectively. This confirms the negative impact of mental fatigue on such indices. Such an effect can be administered and controlled by proper rest breaks.

This research was designed to evaluate the effect of life style-based stress management program on decreasing stress، improving cognitive schemas and increasing self-coherence in highly-stressed university students. 26 highly-stressed female students with the average age of 32±9. 82 years were enrolled and randomly assigned to experimental and control groups. Both before and after the stress management program (LEARN) subjects were asked to complete the perceived stress scale (PSS)، young cognitive schemas and sense of coherence questionnaires. Our statistical analysis comprised mean، standard deviation، frequency indexes، Leven، Kolmogrov-Smirnov and analysis of variance test with repeated measures. The ANOVA and MANOVA tests revealed a significant difference between pre-test and post-test scores of the two groups in terms of perceived stress scale، some cognitive schemas (emotional deprivation، mistrust/abuse، defectiveness/shame، failure، self-sacrifice and emotional inhibition)، and sense of coherence (p<0. 05). The stress management intervention led to decreased stress، improvement of some cognitive schemas and increased sense of coherence in highly-stressed students.

Cognitive deficits in autism spectrum disorders (ASD) affect different aspects of information processing and time perception. This study examined the temporal processing and its relation with executive functions (planning and working memory) in children with ASD as compared to a normal group. To this end، time reproduction task، spatial working memory (SWM) and stocking of Cambridge (SOC) tasks were performed in 14 children with ASD and 14 age-matched healthy control children. Our results demonstrated a significant correlation between time reproduction and working memory and planning. Children with ASD showed deficit in all three tasks as compared to the control group. Having working memory and planning considered as covariant variables، group differences in time reproduction continued to remain significant. Results showed that the impact of autism disorder on time perception was significant even after controlling working memory and planning. Therefore، time perception deficit in children with ASD may not be explained by executive dysfunctions in such a disorder.

According to previous studies، people with emotional states، detect emotional stimuli faster than the control group. Current study would examine this hypothesis. 200 university bachelor students were tested for anxiety and depression using SCID، BDI، BAI، D-scale from MMPI، and the Spielberger trait-state anxiety inventory questionnaires. Then، the attention bias to emotional stimuli was verified by the performance in dot-probe (word) test. The scores were analyzed in SPSS software. According to anxiety and depression scores، participants were divided into four groups including high anxiety-low depression، low anxiety-high depression، high anxiety-high depression، and low anxiety-low depression. Results of the analyses showed that response pattern to emotional/neutral stimuli was not different in these four groups. Subjects who suffer from anxiety or depression do not seem to answer any differently to emotional stimuli. Meanwhile further studies are required to examine the patterns of detecting emotional stimuli in different emotional states.

Epilepsy is a disease of the central nervous system presenting by sudden convulsive attacks over a period of time. A key issue in recognition systems is optimal data acquisition as well as accurate labeling based on chaotic qualitative analyses and confirmatory annotations using expert eyes. To this end، chaotic features such as Petrosian fractal dimension، largest Lyapunov exponent and Hurst exponent were used in this investigation. Such features were submitted to the Bayesian classifier in order to have different categories seperated. Our findings confirmed a chaotic behavior in EEG with minimum embedding dimension reduced in ictal state. Similarly، the complexity of the ictal state was reduced. In addition، our results indicated an average classification accuracy of 99. 2% for normal vs. pre-ictal states; the average classification accuracy is 99. 7% for the normal vs. ictal states and the average classification accuracy is 97. 1% for the pre-ictal vs. ictal states. Chaotic analysis appears to serve as a useful method in representation and recognition of the brain activities in epileptic states.

The purpose of the present study was to investigate the effect of yoga training on cognitive-motor functions in children with attention deficit-hyperactivity disorder (ADHD). A quasi-experimental study was conducted on 26 children with ADHD (20 males and 6 females) aged between 6 and 10 year who referred to the Counseling and Psychological Clinical Shenakht Center of Esfahan in the second half of year 2012. The participants were selected through convenience sampling and were randomly assigned to experimental and control groups. The experimental group received a 12-week yoga training; however، the control group performed their daily activities. Both groups participated in a pre-test and post-test; the experimental group participated in an additional follow-up test four month after the post-test. Conner’s Questionnaire (short form of parents and teacher)، Wechsler Revised Intelligence Test، and an apparatus were used to collect the data on possible diagnosis، children’s IQ، and cognitive-motor functions، respectively. An independent t-test and between groups ANOVA with repeated measure (α<0. 05) were used to analyze the data. There was a significant difference between the experimental and control groups in pre-test and post-test (p< 0. 05) in terms of cognitive-motor functions. A 12-weeks of yoga training appears to leave a significant effect on cognitive functions (selective attention and reaction time). Therefore، yoga may be suggested as an appropriate training method to help improving cognitive functions in individuals with ADHD.

The aim of the present research was to study the effects of experimental induction of positive and negative moods on cognitive processing speed، considering the moderating role of personality dimensions of extroversion and neuroticism. In this quasi-experimental study، 750 students from Zanjan University were randomly selected and completed the Revised Eysenk Personality Questionnaire (EPQ-R). According to the extreme scores in two personality dimensions of extroversion and neuroticism، 4 groups were isolated (extroverts، introverts، neurotics، stables). Then، each group was divided into two equal subgroups. We induced positive mood in first subgroup and negative mood in the second subgroup using affective pictures and stories. After the experimental induction of moods، participants were asked to reply to the PANAS inventory to ensure they have the right mood. Later، participants، cognitive processing speed was tested using “cognitrone” computer program. Data were analyzed using two-way ANOVA، Tukey’s test and one-way MANOVA. According to our findings، extroverts had higher processing speed in positive mood as compared to introverts; however there were no significant difference between the two groups in negative mood. Emotionally-stable individuals had significantly higher speed both in negative and positive moods compared to neurotics. Both extraversion and introversion as well as positive and negative moods alone (not interactive) and the interaction had significant effect on processing speed. There were no gender differences in both groups with regards to the processing speed. Mood and personality characteristics interactively seem to leave an effect on cognitive processing speed.