辨識真實臉孔與圖形化臉孔情緒表達之差異性探討

A Comparison of Identity and Emotional Expression Processing between Real and Line-Drawn Faces

拜科技之賜，人們的社交活動早已不限於面對面的交流，而吾人經常使用的各類通訊軟體皆包含豐富的表情圖案，為冰冷文字添上生動的情緒。在過去，人們的社交活動大多藉由實際的接觸來辨別彼此的情緒狀態，因此以往的研究亦多著重於辨識真實臉孔的情緒表達。本研究利用兩個實驗探討吾人辨識真實臉孔與圖形化臉孔在情緒表達歷程上可能存在的差異。實驗一比較真實臉孔、圖形化臉孔及物體在整體辨識及部件辨識上正確率的差異，發現圖形化臉孔的辨識已脫離辨識真實臉孔的範疇，而與物體辨識較為相近。實驗二則藉由眼動儀的紀錄，檢驗臉孔部件在真實臉孔與圖形化臉孔情緒表達上權重的差異性，並進一步探討語意訊息是否會改變吾人對不同臉孔部件在情緒表達上的權重結果顯示雖然真實臉孔與圖形化臉孔在辨識歷程上有所差異，情緒辨識上圖形化臉孔的正確率較低、反應時間較長，但在眼動儀的資料當中卻發現兩者擁有相似的情緒辨識歷程。再者，提供語意線索並無法提高圖形化臉孔的情緒辨識正確率。以上結果部分解釋了何以現行通訊軟體中的表情圖案需要放大表情特徵以可服圖形化臉孔所造成的訊息減損。

Face processing and recognition has been one of the most productive research areas in cognitive science over the past four decades, and in most studies images of real faces are the focus of inquiry. Owing to the proliferation of technology in social media in recent years, we have witnessed a significant surge of using line-drawn faces and expressions along with their real-face counterparts for purpose of communication. Here in two experiments we examined how line-drawn faces may differ from real faces in terms of identity and emotional expression processing. In Experiment 1, we used the partwhole task and showed that, compared to real faces, line-drawn faces were processed in a more part-based manner similar to non-face objects (i.e., houses). In Experiment 2, we tracked participants' eye movements while they performed a delayed matching-to-sample task, in terms of expressed emotion, where images of either real or line-drawn faces were used as the sample. In addition, we also examined the role a verbal label may play in identifying the facial expression that matched the description. We did this to test the idea whether facial expressions of line-drawn face were in general more symbolically coded than real faces such that a verbal label would be more effective in retrieving those expressed by line-drawn faces. The results indicated that while line-drawn faces differed from real faces in terms of identity processing, they may be quite similar in terms of expression processing. Furthermore, compared to real faces, providing a verbal label failed to offer any additional help locating the matched expression from line-drawn faces, after controlling for the potential speed-accuracy tradeoff with inverse efficiency scores. This might explain why it has become a common practice to exaggerate portrayed expression in line-drawn faces: To overcome the inherently vague signals of emotional expression.