얼굴표정에 함의된 정서 특성에 대한 연구들은 대개 무표정 얼굴을 중립 정서자극으로 사용한다. 그러나 일상생활에서 흔히 무표정은 타인에 의해 부정적 정서의 표현으로 해석되는 경향이 있다. 본 연구에서는 유쾌 혹은 불쾌한 얼굴에 대한 무표정 얼굴의 상대적 현출성을 비교하기 위해 유쾌 또는 불쾌 얼굴표정 방해자극들 사이에 출현한 무표정 표적자극에 대한 시각탐색을 요구하였다. 탐색 과제의 반응시간과 정확도 자료에 대한 분석을 시도한 결과 유쾌보다는 불쾌 방해자극 사이에 표적 자극이 출현한 경우 반응시간이 지연되었으며 정확성 또한 감소한 것이 관찰되었다. 이러한 상대적 부정확성은 무표정과 불쾌 방해자극을 서로 구분하는 민감도(d')의 저하에 의한 것으로 나타났다. 또한 ex-Gaussian 모형에 근거하여 개별 참가자들의 반응시간 분포를 유쾌 혹은 불쾌 방해자극 조건 간 상호 비교하였다. 표적있음 시행의 불쾌조건에서의 반응시간 지연은 의사결정 및 반응선택이 초래하는 편포성 증가에 기인한 것으로 나타났으며, 특히 이러한 반응시간의 지연은 표적없음 시행에서 분포의 전반적 지연과 함께 더욱 두드러졌다. 본 연구의 결과는 유쾌 및 불쾌 표정의 맥락 내에서 무표정한 얼굴이 출현할 경우, 무표정 얼굴은 지각된 정서가(emotional valence) 차원에서 유쾌 표정보다는 불쾌 표정과 상대적으로 구분되기 어려움을 시사한다.
Many studies characterizing perceived emotion on one’s face have used emotionless faces as neutral face stimuli. In our daily circumstances, however, an emotionless face tends to represent a negative expression of emotion rather than purely neutral. The present study aimed to compare the saliency of an emotionless face against either smiling or frowning faces, and asked participants to search for a target of an emotionless face among the distractors of either smiling or frowning faces. The analyses of search found delayed RTs as well as inaccurate search performance if the target was displayed among the frowning distractors rather than among smiling faces. The relative inaccuracy of target search was shown to derive from the decrease of sensitivity (d’) for discriminating the emotionless target from frowning distractor faces. We also compared the search RT distributions according to the ex-Gaussian model across the smiling and frowning distractor conditions. The ex-Gaussian analyses showed that the delayed RTs in the frowning condition owes to an increase of skewness in the distribution as a result of decision and response-selection processes. The skewness became more evident in the target-absent trials with an overall delay in their RTs. The results of the present study indicate that the emotionless faces is more difficult to distinguish from frowning faces than smiling faces if it is displayed among either of the two faces.
Many studies characterizing perceived emotion on one’s face have used emotionless faces as neutral face stimuli. In our daily circumstances, however, an emotionless face tends to represent a negative expression of emotion rather than purely neutral. The present study aimed to compare the saliency of an emotionless face against either smiling or frowning faces, and asked participants to search for a target of an emotionless face among the distractors of either smiling or frowning faces. The analyses of search found delayed RTs as well as inaccurate search performance if the target was displayed among the frowning distractors rather than among smiling faces. The relative inaccuracy of target search was shown to derive from the decrease of sensitivity (d’) for discriminating the emotionless target from frowning distractor faces. We also compared the search RT distributions according to the ex-Gaussian model across the smiling and frowning distractor conditions. The ex-Gaussian analyses showed that the delayed RTs in the frowning condition owes to an increase of skewness in the distribution as a result of decision and response-selection processes. The skewness became more evident in the target-absent trials with an overall delay in their RTs. The results of the present study indicate that the emotionless faces is more difficult to distinguish from frowning faces than smiling faces if it is displayed among either of the two faces.
