台灣嬰兒和成人的他種族效應之探討

Exploring the Other-Race Effect in Taiwanese Infants and Adults

「他種族效應」是指成人辨識自己種族臉孔的能力優於辨識其他種族臉孔的能力。Kelly、Quinn等人（2007）與Kelly等人（2009）發現三個月大的嬰兒可以區辨自己和其他種族的臉孔，但是到了九個月大僅只能區辨自己種族的臉孔；研究者認為這是「知覺窄化」。然而，目前關於嬰兒期「他種族效應」的主要發現僅證明嬰兒辨識其他種族臉孔的能力隨著年齡增長而變差，缺乏研究證據同時探討嬰兒辨識自己種族臉孔的能力是否會進步。因此，本研究主要目的乃透過操弄不同難易程度的臉孔刺激圖片，來探討台灣地區四個月、六個月和九個月大的嬰兒辨識自己與他種族臉孔的能力是否會隨著年齡增長而有所變化。同時也測試成人作為參照值，並檢測刺激難易度之操弄有效性。嬰兒實驗結果顯示四個月大的嬰兒僅能區辨亞洲人簡單程度的臉孔，六個月大的嬰兒可以區辨亞洲人、白種人和黑種人簡單程度的臉孔，九個月大的嬰兒進一步可以區辨亞洲人和白種人中等程度的臉孔。成人實驗結果看到「他種族效應」，並證明刺激難易度的操弄是有效的。整體而言，本研究發現本種族優勢讓嬰兒在辨識自己種族臉孔的能力在四個月就已出現，他種族效應則是發生在六至九個月之間；然而辨認其他種族的能力（如黑種人）並不會消失，僅是維持在最基本的辨識層次上。換言之，嬰兒辨識臉孔的能力會隨著年齡增長而變得更好，同時又因為受到經驗的調控，使得辨識同種族臉孔的能力有所提昇。

The other-race effect (ORE) refers to the phenomenon that we can discriminate own-race faces better than otherrace faces. The present study aims to explore the face processing ability for own-race and other-race faces in Taiwanese infants aged between 4 and 9 months when the visual system is still maturing. The stimuli contained faces of three ethnic groups (Asian, Caucasian, and African). In each race, the face discrimination task had three levels of difficulty (Easy, Median, and Hard). The visual paired-comparison (VPC) task was used to assess 4-, 6-, and 9-month-old infants' discriminability for the familiar/novel faces via recording infant's looking time. Comparable 3-alternative forced-choice procedure was used in the adult experiment except that an additional “identical” condition was added. The results showed that 4-month olds can only discriminate Asian “easy” faces. 6-month olds can discriminate “easy” faces of all three ethnic groups. 9-month olds can further discriminate “median” Asian and Caucasian faces but not African “median” faces. For adults, the accuracy decreased and response time increased as the stimulus difficulty increased, indicating the validity of the stimulus difficulty. In conclusion, own-race advantage emerges around 4 months of age, while ORE may take place between 6 and 9 months as the discriminability for African faces does not improve. Taken together, these findings suggest a mixture of general improvement in face processing ability as well as a specific tuning by the own-race experience.