تاثیر هدایت توجه اولیه بر محدودیت‌های توجهی مرکزی تکالیف دوگانه با سطوح دشواری متفاوت: یک مطالعه پتانسیل وابسته به رویداد

مقدمه: نشان داده شده است که جهت‌ دهی اولیه توجه به سمت موقعیت هدف موجب تسهیل پردازش ‌های حسی_ادارکی هدف می ‌شود. با این حال مشخص نیست که آیا توجه بینایی_فضایی تحت کنترل منابع محدود توجهی مرکزی هست یا خیر. هدف پژوهش حاضر بررسی تغییرات رفتاری و الکتروفیزیولوژیک بر اثر هدایت تسهیلی توجه اولیه بر محدودیت‌های توجهی مرکزی حین اجرای تکالیف دوگانه با سطوح دشواری متفاوت بود. روش کار: 24 آزمودنی به ‌طور داوطلبانه انتخاب و به‌ طور تصادفی در دو گروه با تکالیف ساده و انتخابی گمارش شدند. از یک الگوی تکلیف دوگانه همراه با و بدون نشانه استفاده شد، که در آن تکلیف دوم ساده یا انتخابی بود و قبل از محرک نخست یک نشانه ارائه می‌شد. فاصله زمانی بین تکلیف اول و دوم 200، 400 و 800 هزارم ثانیه بود. زمان پاسخ به محرک نخست و دوم و مولفه‌های پتانسیل وابسته به محرک دوم ثبت و تحلیل شدند. یافته‌ها: الگوی ساده زمان پاسخ سریع‌ تری نسبت به الگوی ترکیبی داشت. همچنین، زمان پاسخ هدف در موقعیت سازگار سریع‌تر از موقعیت ناسازگار بود. کمترین زمان واکنش‌ها مربوط به گروه ساده و بیشترین متعلق به گروه انتخابی بود. اثر اصلی الگو، گروه و فاصله زمانی بر مولفه‌های حسی اولیه p1 و n1 معنادار بود. نتیجه‌گیری: تسهیل مراحل حسی_ادراکی اولیه از طریق هدایت توجه به سمت موقعیت سازگار می‌تواند موجب کاهش تداخل تکالیف دوگانه شود.

The effect of directing early attention on the central attentional limitation of dual tasks with various difficulty levels: An event-related potential study

IntroductionsSeveral empirical results demonstrate that the human information processing system is sharply limited in several different ways. Visualspatial attention is critical for selectively processing the most relevant visual stimuli in the early stage of processing (4). It seems that more than one stimulus can proceed in the early stage of processing. Another limitation arises in multitasking situations, in which relevant information after early selection would be processed more in the later capacitylimited stage(s). The psychological refractory period (PRP) paradigm has been used extensively to study attentional limitations in the central or late processing stages (15). There are two types of hypotheses concerning the interaction of visualspatial attention and response selection capacitylimited stages (16). Some studies have provided evidence that they operate independently, while others have provided evidence in conflict with these results. The current study presents new evidence to add valuable empirical evidence about the relation between orienting and central attentional limitation by manipulating visualspatial attention and central attention in a modified PRP paradigm.MethodsTwentyfour students were recruited with flyers posted on the Shahid Beheshti University campus. Participants ’ age ranged from 18 to 30 years, and three participants were lefthanded. Within each trial, three main stimulus events were presented in succession (cue, target 1, and target 2). Only T1 and T2 required a response to be made; however, the cue did not require any response. Four trial conditions emerging from the combination of two cue conditions and two types of T2. T1 could be either cued or uncued; the cue and target locations were the same in cued trials. In the uncued condition, the cue was in the opposite location to that of T1. T2 was either a detection or discrimination task. In detection trials, T2 was the detection task, and T2 was the colored discrimination task in discrimination trials. The response time to the first and second stimulus and eventrelated potential was recorded and analyzed.ResultsA 2x2 x3 withinsubjects ANOVA was used to analyze RT1 data for trials, with groups (detection, discrimination), cueing (cued, uncued), and SOA (200, 400, 900ms) as factors. The main effect of the group on RT1 was significant, F (1, 23)=16.706, P<0.001; with RT1s being slower overall to the detection group (M=557.0) than the discrimination group (M=738.0). Cueing had a significant effect on RT1, F (1, 23)=8.56, P<0.008, with RT1s being slower overall to the cued location (M=630.0ms) than the uncued location (M=684.3ms). The main effect of SOA on RT1 was significant, F (2, 46)=20.33, P<0.001; as SOA decreased, RT1 increased. None of the twoway interactions and threeway interactions on RT1 was significant.A 2x2x3 withinsubjects ANOVA was used to analyze RT2 data for trials, with groups (detection, discrimination), cueing (cued, uncued), and SOA (200, 400, 900ms) as factors. The main effect of group on RT2 was significant, F (1, 23) =50.095, P<0.001; with RT2s being slower overall to the detection group (M=546.0) than the discrimination group (M=701.0). Cueing had a significant effect on RT2, F (1, 23)=8.56, P<0.008, with RT2s being slower overall to the cued location (M=582.0ms) than the uncued location (M=665.3ms). The main effect of SOA on RT2 was significant, F (2, 46)=8.24, P<0.001; as SOA decreased, RT1 increased. None of the twoway interactions and threeway interactions on RT2 was significant.Mean response times to the first and second stimulus were significantly faster in the valid than in the invalid condition (F=8.56, P=0.009). In Short SOA, analyses on T2locked ERPs revealed that the amplitude of the occipital P1 (MD=2.44, t=3.12, P=0.007) and N1 (MD=2.49, t=4.05, P=0.001) was more significant in the valid cue condition than in the invalid cue condition. In long SOA, the occipital P1 (MD=2.28, t=3.67, P=0.002) and N1 (MD=2.18, t=2.49, P=0.02) was more significant in the valid than invalid condition. The latency of the occipital P2 was more significant in the valid than invalid condition (MD=1.73, t=6.79, P=0.04).The simple pattern had a faster response time than the combined pattern. The main effect of pattern, group, and time interval on primary sensory components P1 and N1 was significant.ConclusionThe present study used a spatial cue as a tool to orient visualspatial attention in the context of the psychological refractory period paradigm. This combination of different paradigms allowed to study the underlying mechanisms that mediate visual spatial attention and central attentional operation. Interestingly, the obtained results showed a significant reduction in PRP interference in the cued conditions (RT2 was smaller at the cued conditions than uncued conditions across all task 2 difficulty and SOAs). It suggests that the facilitation effect of orienting on task1 processing had consequence effects on the second task processing. There are some explanations for these findings based on bottleneck models and capacity sharing models. Each of these theories that consider facilitation in the first task processing stages leads to whether a decrement in the waiting time of the second task to begin its processing (based on the bottleneck models) or to allocate more attentional capacity to the second task (based on the capacitysharing model). Therefore, facilitation of the first task processing in the PRP paradigm affected the second task processing, resulting in more negligible PRP interference. These findings provided evidence for an interaction between the visuospatial attention and central attentional limitation, which is consistent with electrophysiological evidence presented by Brisson and Jolic oelig;ur (2007) (16) and Lien et al. 2011 (13). However, this finding did not prove the findings from Pashler 1998 (7), Pashler 1991 (14), Johnston et al. 1995 (15).Therefore, facilitating the early sensoryperceptual by directing attention toward the cued location would reduce the dualtask interference.Ethical ConsiderationsCompliance with ethical guidelinesAll methods were carried out in accordance with the relevant guidelines and regulations of the Biological Research Ethics Committee of Shahid Beheshti University. All the experimental protocols were approved by the Biological Research Ethics Committee of Shahid Beheshti University (IR.SBU.REC.1395.002). Informed consent was obtained from the participants before participating in the study. Besides, all participants were free to cancel their cooperation at any stage of the test.Authors rsquo; contributionsMaryam Kavyani and Alireza Farsi: Designed and conceived the presented idea, performed experiments, analyzed data and cowrote the paper. Maryam Kavyani: Performed testing section during the experiment. Maryam Kavyani, Alireza Farsi, and Behrouz Abdoli Supervised the research. All authors provided critical feedback and helped shape the research, analysis, and manuscript.FundingThis research received no financial support from any funding agency in the public, commercial, or notforprofit sectors. AcknowledgmentThe authors would like to thank all participants in this study.Conflict of interestThe authors acknowledged no potential conflicts of interest regarding this article rsquo;s research, authorship, and/or publication.