Perceived eye size is larger in happy faces than in surprised faces

We demonstrated that perceived eye size is affected by facial expression. Stimuli were composite photographs generated from happy, surprised, and neutral faces. The top halves of the original photographs were separated from the bottom halves by a horizontal line below the eyes, and were pasted onto the superior areas of the happy and the surprised faces. Thus, the composites were happy faces and surprised faces with happy eyes, neutral eyes, and surprised eyes. When the eyes of the happy and the surprised face composites with the same top halves were compared by 142 naïve observers, the happy face composites were judged to have larger eyes than the surprised face composites.