تاثیر تحریک فراجمجمه‌ای با جریان مستقیم بر تصمیم‌گیری ریسک‌پذیر دانش‌آموزان شطرنج باز براساس ویژگی های شخصیتی درونگرا و برونگرا

هدف: هدف از این پژوهش؛ بررسی تاثیر تحریک فراجمجمه ای با جریان مستقیم بر تصمیم‌گیری ریسک‌پذیر دانش‌آموزان شطرنج باز، با توجه به ویژگی های شخصیتی آن ها بود. مواد و روش ها: در این پژوهش، تعداد 28 دانش آموز متوسطۀ دوم که در ورزش شطرنج فعالیت داشته و در مسابقات لیگ استانی و کشوری شطرنج حضور داشتند، شرکت نمودند که بر اساس پرسش نامۀ 5 عاملی ویژگی های شخصیتی نئو به دو گروه؛ 14 دانش آموز برون گرا (0.88±17) و 14 دانش آموز درون گرا (1.02±16.5) تقسیم شدند. هر آزمودنی در سه جلسۀ مجزا با فاصلۀ حداقل 72 ساعت استراحت بین جلسات در آزمایشگاه حضور یافت. آزمودنی ها در هر جلسه، قبل از هر نوع تحریک، تکلیف شرط بندی آیووا و بازی رایانه ای لیچز را انجام دادند. سپس، تحت یکی از 3 شرط؛ آنودال راست/کاتودال چپ، کاتودال راست/آنودال چپ و شَم به مدت 20 دقیقه با شدت 2 میلی آمپر بر روی قشر خلفی جانبی پیش پیشانی مورد تحریک الکتریکی قرار گرفتند. آزمودنی ها، پس از اتمام تحریک، مجدداً تکلیف شرط بندی آیووا و بازی رایانه ای لیچز را انجام دادند. یافته ها: تحلیل داده ها با استفاده از آنوای دو راهۀ مرکب نشان داد که در تکلیف شرط بندی آیووا، بین تحریک آنودال راست/کاتودال چپ و کاتودال راست/آنودال چپ براساس ویژگی های شخصیتی تفاوت معناداری وجود داشت (0.001=p). نتیجه گیری: یافته های این پژوهش نشان داد که تحریک فراجمجمه ای با جریان مستقیم براساس ویژگی های شخصیتی بازیکنان شطرنج تاثیر متفاوتی بر روی تصمیم گیری آن ها دارد. به طوری که؛ نتایج پژوهش نشان داد بازیکنان برون گرا ریسک پذیرتر و بازیکنان درون گرا محتاطانه تر عمل می کردند.

effect of transcranial direct current stimulation on risky decision-making of student chess players based on their introverted and extroverted personality traits

background and purposerisky decision-making is a type of decision-making process that occurs when an individual faces options with potential positive and negative outcomes in the present and future. these outcomes are associated with varying degrees of probability and uncertainty (royall & kurtz, 2010). this process is encoded in the dorsolateral prefrontal cortex of the brain, encompassing the logical and calculated aspects of decision-making (bechara, tranel, damasio & damasio, 1996; hastie & dawes, 2009).personality traits, as one of the most significant individual differences, have a considerable impact on risky decision-making (levitch et al., 2020). in sports, this process is a key cognitive function that varies depending on the nature of the sport (filho, tenenbaum & yang, 2015). chess, as a mental sport, enhances cognitive abilities such as concentration, problem-solving, strategic planning, and creativity (kazemi et al., 2012).recent studies have shown that transcranial direct current stimulation (tdcs) can influence various cognitive functions, including impulsivity and risky decision-making. therefore, the main research question is whether personality traits play a role in moderating the effect of tdcs on risky decision-making in chess players and how this ability can be enhanced through brain stimulation.materials and methodsthis study employed a pre-test-post-test design with a control group, conducted in a double-blind, counterbalanced manner. after assessing the inclusion and exclusion criteria, a total of 28 participants, including 14 extroverted students (mean age: 17 ± 0.88) and 14 introverted students (mean age: 16.5 ± 1.02), were selected as the statistical sample based on the neo five-factor inventory of personality traits. the study protocol was approved by the national ethics committee for biomedical research of iran (code: ir.uma.rec.1402.103) and conducted in accordance with the helsinki declaration. prior to the experimental sessions, participants attended an orientation session to familiarize themselves with the research procedures and the tdcs intervention. subsequently, each participant visited the laboratory on three separate occasions, with 72-hour intervals between sessions. during each session, before and after applying one of the three types of electrical stimulation (right anodal/left cathodal, left anodal/right cathodal, or sham stimulation at 2 ma for 20 minutes over the dorsolateral prefrontal cortex), the iowa gambling task and the lichess computer game were administered.findingsoverall results of the iowa gambling task (igt), based on personality traits at pre- and post- tdcs intervention under 3 different stimulation types are demonstrated in table 1.the results of the two-way mixed anova indicated that the interaction effect between the between-group factor (personality traits) and the within-group factor (type of stimulation) was statistically significant (p = 0.016 < 0.05). given the significance of the interaction effect, the mean comparisons of extroverted and introverted groups under three different transcranial direct current stimulation (tdcs) models were examined separately. the findings revealed that participants in both extroverted and introverted groups exhibited different performances across various stimulation sessions. additionally, the main effect of the between-group factor was analyzed, and the results showed no significant difference between extroverted and introverted groups in terms of personality traits across any of the stimulation types (f(1,26) = 1.053, p = 0.314). on the other hand, the main effect of the within-group factor indicated a significant difference among the three stimulation models (f(2,25) = 14.08, η² = 0.53, p = 0.001). the eta squared value (η² = 0.53) suggests a very large effect size. pairwise comparisons of the three stimulation models using bonferroni correction revealed that the risk-prone decision-making scores were significantly higher in the right anodal/left cathodal stimulation condition compared to the left anodal/right cathodal condition (p = 0.001). conclusionin general, brain electrical stimulation (tdcs) can significantly influence brain activities related to risky decision-making. specifically, anodal stimulation of the right hemisphere combined with cathodal stimulation of the left hemisphere increases activity in the dorsolateral prefrontal cortex. conversely, cathodal stimulation of the right hemisphere and anodal stimulation of the left hemisphere may decrease activity in this region. these changes in brain activity can affect behavior. for instance, extroverted individuals under right-anodal/left-cathodal stimulation experience increased activity in the dorsolateral prefrontal cortex and show a greater tendency toward risk-taking. on the other hand, introverted individuals under right-cathodal/left-anodal stimulation experience reduced activity in this area and act more cautiously. these findings indicate that individual personality traits can modulate the effects of tdcs on decision-making and risky behaviors.this research highlights the importance of considering personality traits when examining the impact of tdcs on cognitive and behavioral processes, particularly in areas such as sports and high-risk activities. such findings could be valuable in developing personalized interventions and tailored training programs aligned with individual personality characteristics to optimize risky decision-making and improve performance across various fields. additionally, future studies should carefully consider stimulation protocols, hemispheric differences, and individual variations in decision-making types during study design.