| 摘要: | 數字表徵可能以多重形態存在於人類認知系統。SNARC效應和FoNARC效應分別說明了數字表徵除了有離散性的線性順序特性，也具備連續性強弱大小量特性，而目前尚未有研究探討兩類表徵間的關係。本研究以催眠提示作為操弄數字表徵中既有之順序或量概念之工具，以探討兩者相互轉換時之關係為何。
研究一探討非催眠提示在聽覺奇偶數判斷作業上之SNARC強度與受試者催眠易感性程度間的相關，分別給予兩組受試者逆向與順向提示後進行作業；結果顯示聽覺奇偶數判斷作業的 SNARC 強度未如以往呈現視覺數字刺激之研究所發現般穩定，但接受逆向提示之受試者，其逆向SNARC強度和催眠易感性程度達顯著正相關，這說明即使在非催眠的情況下，催眠易感性程度仍可作為提示效果之預測指標，而順逆向提示結果之差異可能在其誘受試者注意力投入程度之差異。
研究二則以催眠提示操弄數字表徵中「順序」或「量」的概念，藉由 SNARC與FoNARC 效應來觀察這兩種概念互相轉換；接受測試高催眠易感性受試者裡，一組接受操弄量之順/逆向提示、另一組接受操弄順序之順/逆向提示後，以空間 (左右按鍵) 或非空間 (輕重握力) 反應進行視覺奇偶數判斷作業。結果顯示在給予操弄量提示之情況下，順/逆向提示和空間/非空間反應方式達顯著交互作用；在順序提示情況則無此效果。此結果意味著「數字表徵中，僅被操弄的量概念轉換為非空間反應碼之效率，強過於其轉換為空間反應碼之效率」；也就是說：當受試者心中量概念被加強或反轉時，較易自動對應到非空間反應碼；但順序概念被加強或反轉時，卻不一定會轉換成相應之空間反應碼或非空間反應碼。而從腦造影的結果發現：(1) 在給予操弄順序之順向催眠提示下，SNARC強度和右背外側前額皮質的血氧濃度變化達顯著相關；(2) 而在給予操弄量之順向催眠提示下，FoNARC強度和左腹側頂葉區的血氧濃度變化達顯著相關； (3) 但在給予操弄量之反向催眠提示下，SNARC強度和右前額區、左角回及右丘腦的血氧濃度變化達顯著相關；(4) 反之，在給予操弄順序之反向催眠提示下，FoNARC強度和左前外側額葉皮質及左後側頂葉內溝血氧濃度變化達顯著相關。此研究之結果發現了不同型態數字表徵間訊息互通時的不對稱關係及其對應的神經機制，未來可進一步探討數字表徵中順序及量概念的本質。
;Numbers can be mentally represented in distinct forms: While the SNARC effect indicates the representations of a number line with discrete rank units, the FoNARC effect illustrates a magnitude form associated with continuous quantity. The current study aims to investigate the relationship between the rank and the magnitude forms of numerical representation by using hypnotic suggestion as a tool to alter the conversion between the two forms.
The Study 1 investigated the correlation between the strength of SNARC and hypnotic susceptibility under the influence of non-hypnotic suggestions. One group of participants received suggestions of the number-space mapping reversing the ordinary order, and the other group received ordinary suggestions. The results showed that the strength of the auditory SNARC was not as stable as those reported in previous studies presenting numerical information visually. However, under the reverse suggestion, the strength of SNARC was significantly correlated with hypnotic susceptibility. We speculate that under unfamiliar and attention-demanding circumstances, hypnotic susceptibility could be a significant predictor of the suggestion effect, even under non-hypnotic states.
The aim of Study 2 was to examine the conversion across rank/magnitude forms of numerical representation and the underlying neural mechanisms. Here one group of participants received the hypnotic suggestion of manipulated rank, and the other group received suggestion on manipulated magnitude before performing a visual parity judgment requiring spatial or non-spatial responses. The behavioral results showed a significant interaction between the type of suggestion and response under the manipulated magnitude condition. This finding implies that only the altered magnitude form could be represented by the non-spatial response but not by the spatial response. In other words, the altered magnitude form and the altered rank could not easily associate with each other and be significantly represented by the spatial response and the non-spatial response.
As for the FMRI results, the strength of SNARC in the ordinary suggestion (OS) condition of the rank group correlated with the activation in the right dorsolateral prefrontal cortex, which suggested this region to be involved in the numerical rank that represents the knowledge of rank form. Conversely, the strength of FoNARC in OS condition the magnitude group correlated with the activation in the left ventral intraparietal area, which suggested this region to be involved in the numerical magnitude that represents the knowledge of magnitude form. Interestingly, the strength of SNARC in the reverse suggestion (RS) of the magnitude group correlated with the activation in the right superior frontal area, the left angular gyrus and the right thalamus, which suggested the regions to be processing the conversion from the reversed magnitude form to the rank form. Conversely, the strength of FoNARC in the RS condition of the rank group correlated with the activation in the left ventrolateral prefrontal cortex and the left posterior intraparietal sulcus, which suggested these regions to be processing the conversion from the reversed rank form to the magnitude form. To conclude, these findings demonstrate an asymmetric flow of information between the numerical magnitude and rank in numerical representations: the processes of that the altered magnitude and the altered rank representations elicit to each other needed the resources both related the numerical magnitude and the numerical rank; especially the processing of that the altered magnitude form elicit the rank form (namely represented by the spatial response) needed more resources rather the opposite direction. |
