自主性作業轉換： 探討意念控制與刺激驅動之角色

Voluntary Task Switching: The roles of volitional control and stimulus-driven processes in voluntary task switching

陳柏伃(Poyu Chen)

指導教授 ： 蔡玲玲 ； 謝淑蘭

國立中正大學/社會科學院/心理學系/博士(2013年)

摘要

自主性作業轉換派典為近年來探討行為控制的工具之一。藉由探討自主性作業轉換派典中，受試者如何以高等執行控制功能之意念控制，調節來自刺激驅動的影響，讓我們更加瞭解人類的心智運作。本論文的研究分為兩大部分，第一部分的研究包含實驗一與二，利用具有由左到右的水平表徵之數字為刺激，進一步操弄反應鍵之空間表徵，探討數字與反應鍵之空間表徵重疊與否的特性，是否會造成作業選擇的偏誤。其中以受試者間設計之方式，隨機分配受試者至下列兩組不同的反應鍵安排：與數字表徵同疊之水平組(作業安排呈現內/外)、以及不與數字表徵重疊之垂直組（作業安排呈現上/下）。實驗一結果顯示，反應鍵為水平呈現組，其內/外表徵與數字刺激的水平表徵有所重疊，受試者將傾向於選擇刺激—反應鍵空間表徵一致者，而非刺激—反應鍵空間表徵不一致者。反之，垂直呈現組的上/下表徵，因與水平數字表徵沒有重疊，故沒有作業選擇的偏誤。實驗二則進一步釐清此刺激—反應鍵一致性之效果，是否來自於反應鍵的極性安排; 結果顯示，造成自主性作業選擇的偏誤，主要取決於刺激與反應之空間表徵是否重疊、而非單純來自反應鍵的極性安排。
第二部分的研究則佐以事件相關電位技術，探討兩議題：其一同時以受試者內設計模式，進行自主性與指示性作業轉換派典，以利同時比較兩作業派典之異同。其二為延伸第一部分的研究結果，探討反應鍵安排對於作業準備策略的效果，隨機分派受試者至手—作業連結組、以及手指—作業連結組。在準備鎖定之事件相關腦波證據指出，指示性轉換作業派典中的轉換嘗試次，在頂葉處引發較大的P3b 活動、且不受反應鍵操弄之影響。相反地，我們觀察到只有在反應鍵安排為手—作業連結組，其自主性作業轉換派典中的轉換嘗試次，有一頂葉較大的contingent negative variation (CNV)負波疊加於一正波之上; 而在手指—作業組，則只有觀察到頂葉正波，而無轉換間的差異。為了瞭解「動作準備」在手—作業連結組的角色，以動作準備相關腦波(lateralized readiness potentials) 進一步檢驗，並發現指示性與自主性作業轉換中的動作準備歷程相同。整體來說，自主性作業轉換所引發的準備歷程，與指示性作業轉換可能不同; 且反應鍵的安排似乎會進一步引發受試者在自主性作業轉換派典下採取不同的準備策略。

關鍵字

策略 ； 事件相關電位 ； 事件編碼理論 ； 刺激-反應一致性 ； 自主性作業轉換 ； 作業選擇 ； P3b ； CNV ； 動作準備相關電位

並列摘要

Recently, the voluntary task-switching (VTS) paradigm has been proposed as a method for exploring the interplay between top-down volitional control and bottom-up stimulus-driven effects in voluntary action control. In the Part I study, we investigated how task selection is biased by inherent stimulus characteristics. Specifically, we examined whether an irrelevant stimulus representation coincides with specific response representation to bias task choices in terms of the stimulus-response (S-R) correspondence effect. Two experiments were conducted to manipulate the action code representation to either overlapped (horizontal layout condition) or non-overlapped (vertical layout condition) with the digit representations. The results of Experiment 1 demonstrated participants tended to categorize a digit as the S-R correspondent task more often than the S-R non-correspondent task only when the action code representation overlapped with the digits. Furthermore, Experiment 2 confirmed the S-R correspondence effect was not due to the response polarity assignment.
In the Part II study, we investigated VTS and instructed (ITS) task switching paradigms involved common or distinct neural mechanisms by examining event-related potentials (ERPs) using a within-subjects design. Furthermore, given that effector-to-task mapping might elicit participants’ different preparatory strategies, we assigned participants to one of two mapping groups: the hand-to-task (HAND) or finger-to-task (FINGER) group. Interestingly, the preparatory ERPs showed the effector manipulation resulted in differential ERP modulations. In the HAND group, there was a greater posterior CNV superimposed on a positive-going deflection for the switch trials in the VTS and an enhanced positivity for the switch trials in the ITS; in the FINGER group, no switch-specific CNV modulations but only a positive-going deflection was identified in the VTS, whereas a robust posterior switch-related positivity was found in the ITS. Furthermore, the foreperiod LRPs analysis indicated the enlarged CNV for voluntary switching was more than motor-specific preparation in the HAND group. Together, Part II study provides the direct EEG evidence to suggest the reconfiguration process differs between VTS and ITS. Notably, the reconfiguration process of VTS is further influenced by participants’ own strategy.

並列關鍵字

Strategy ； theory of event coding ； S-R correspondence effect ； voluntary task switching ； task selection ； ERPs ； P3b ； CNV ； LRPs

參考文獻

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