文化價值對大腦處理眼神線索群體一致性的影響：功能性核磁共振造影研究

Abstract

背景： 文化反映出人與環境、社會之間的互動，也是建構人們如何感知外部世界的一項重要指標。除了直接或間接塑造我們特有的思維方式，更影響著人們如何詮釋自己，以及定位與外在環境之間的關係。隨著文化神經科學的興起，越來越多研究報告指出，集體主義者較易察覺主體及其背景間的關係，而個人主義者則對於主體的關注程度比環境更為敏感；亦即在社會互動時，人們對社會線索的覺察會受到不同文化價值的形塑，產生不同的知覺處理及認知歷程。另外，在諸多社會線索類型中，以眼神線索尤具傳達社交互動訊息的角色；再者，日常生活中除了單一眼神線索的讀取，同時處理眾多眼神線索更是社交常見的可能情境，例如：人來人往的街道。然而，在過去跨文化之研究領域中，大多著墨於仿現實生活之主體背景的知覺處理，少有探討文化差異下人們在對社會線索－尤其是同時處理眾多眼神線索所引發的知覺處理之異同。 目的： 研究有兩個主要目標：1. 探討文化價值如何在不同的社會情境（例如：周遭眼神一致或不一致的情況）下影響個人對社會線索的反應以及對神經生理的影響。 2. 它背後可能的神經機制為何？ 方法： 此研究收集65位來自兩種不同文化背景的志願者，包括西方國家以及台灣。首先，請受試者完成評估文化價值程度的問卷，接著請他們注視視野中央已經畫好眼神方向的臉部卡通圖，並分別在中央臉圖旁邊放上四張眼神方向和中央一致或不一致的臉圖，要求受試者注視中央並以按鍵作答。我們於測試同時分別記錄反應時間及施行功能性核磁共振掃描。 結果： 根據SCS的分數，台灣人大多屬集體主義者，而西方國家受試者大多是個人主義者。此外，負的SCS分數和ICC呈現正相關傾向;核磁共振的影像在不同組別以及不同情境下，分別呈現不同腦區不同程度的活化。另外，於ROI分析發現，ICC和右側中額葉的活化成正比。 結論： 在台灣受試者中占大多數的集體主義者在感受外在刺激時，很容易被周圍的社會線索所影響；這或許是因為這群人的右側中額葉在知覺處理的過程中，比個人主義者更容易活化，因而將腹側注意力網絡(ventral attention network)的訊息傳到背側注意力網絡(dorsal attention network)，導致無法專注。相對而言，由於右側中額葉相較不活化的緣故，傾向個人主義的西方人在知覺處理之過程中，較少被周圍的線索影響且較能獨立思考。此篇研究顯示，人類對社會線索的知覺處理會受到文化價值觀的影響，並證實：在進行眾多眼神線索的知覺處理時，集體主義者相對於個人主義者較容易被目標物及其周遭關係所影響。

Background: Culture is an important predictor that reflects how people interact with the environment and the gregarious society, and seems to be capable of shaping how people perceive the outer world. Increasing evidence suggests that individuals from collectivistic cultures are more sensitive to relationships between objects and their contexts, whereas individuals from individualistic cultures are more sensitive to focused objects of the environment. However, the influence of cultural values on an individual's social attention and its underlying neural mechanisms remain unclear. Objectives: There are two primary aims for the current research：1. How do cultural values influence an individual’s behavioral and neurophysiological processing of social cues under different social contexts (i.e., congruent/incongruent surrounding eye gazes) ? 2. What are the underlying neural mechanisms？ Methods: 65 volunteers of two different cultural origins, Western countries and Taiwan, participate in a gaze flanker task during an fMRI scan. For each trial, we presented a central face gazing toward the left or the right side simultaneously flanked by 4 peripheral faces gazing toward the same (congruent condition) or different (incongruent condition) directions as the central face. Participants were instructed to pay attention to the central face and respond to its gaze direction with button presses. Results: Taiwanese are mostly composed by collectivists whereas people from Western countries consist of individualists, chiefly according to SCS scores. The ICC in the flanker task was marginally correlated with smaller SCS scores. fMRI results also identified the more activated brain area in different conditions and groups. The ROI analysis revealed that ICC is proportional to right middle frontal gyrus activation. Conclusion: Collectivists, who are predominant in the Taiwanese group, are prone to be affected by surrounding social cues during perceptual processing due to the stronger activation of right middle frontal gyrus, the important gateway between ventral and dorsal attention network. Conversely, individualists, like Westerners, are less distracted by surrounding cueing due to the relative inactive right middle frontal gyrus, leading to activation in dorsal attention network only, and rendering people more focused and independent. These findings provide evidence that our perceptual processing of social cues is modulated by cultural values and suggest that people from a collectivistic culture are indeed affected more easily by the interrelationship between objects and their contexts than people from an individualistic culture.