Facial expressions affect the memory of facial colors

Abstract

Facial color influences the perception of facial expressions, and emotional expressions bias how facial color is remembered. However, it remains unclear whether facial expressions affect daily facial color memory. The memory color effect demonstrates that knowledge about typical colors affects the perception of the actual color of given objects. To investigate the effect of facial color memory, we examined whether the memory color effect for faces varies depending on facial expression. We calculated the subjective achromatic point of the facial expression image stimulus and compared the degree to which it was shifted from the actual achromatic point between facial expression conditions. We hypothesized that if the memory of facial color is influenced by the facial expression color (e.g., anger is a warm color, fear is a cold color), then the subjective achromatic point would vary with facial expression. In Experiment 1, we recruited 13 participants who adjusted the color of facial expression stimuli (anger, neutral, and fear) and a banana stimulus to be achromatic. No significant differences in the subjective achromatic point between facial expressions were observed. Subsequently, we conducted Experiment 2 with 23 participants because Experiment 1 did not account for the sensitivity to color changes on the face; humans perceive greater color differences in faces than in non-faces. Participants selected which facial color they believed the expression stimulus appeared to be, choosing one of two options provided to them. The results indicated that the subjective achromatic points of anger and fear faces significantly shifted toward the opposite color direction compared with neutral faces in the brief presentation condition. This research suggests that the memory color of faces differs depending on facial expressions and supports the idea that the perception of emotional expressions can bias facial color memory.

Figure 1.

(A) Examples of the color state for each image condition. (B) The mean a*-b* values of the image stimuli. A red diamond represents the mean of all face image stimuli, and a yellow diamond represents the mean of the banana stimulus. Blue lines denote the averages of color change axes for the face and banana stimuli. Individual points on the right side represent each face image stimulus, including three facial expressions and four individuals. The red diamond corresponds to the left side. The faces in the figure are one of the author's faces (Y.H.), which was not used in the experiment.

Figure 2.

Procedure of Experiment 1. Notably, the ratio of the screen to the stimulus depicted in this figure differs from the actual ratio.

Figure 3.

Results of Experiment 1. Participants’ mean of the achromatic adjustment point (A, Facial expression condition; B, Banana condition). Each gray points show individual data. Error bars represent the standard error of the mean.

Figure 4.

Each axis of condition in Experiment 2. The original-opposite color axis in the figure is the average line of all the faces.

Figure 5.

Procedure of Experiment 2.

Figure 6.

Results of Experiment 2. Participants mean of PSE ([A] original-opposite color axis, [B] a* axis, [C] b* axis). The closer the value is to “0,” the closer the subjective achromatic point is to the physical achromatic point. A larger positive value indicates that the subjective achromatic point is more shifted toward the original color (A)/red (B)/yellow (C), whereas a larger negative value indicates that the subjective achromatic point is more shifted toward the opposite color (A)/green (B)/blue (C). The other formats were the same as in Figure 3.