The Stimuli: Chicago Face Database

Thirty high-resolution photograph images were presented to the participants that show both male (n = 15) and female faces (n = 15). Three different orders of image presentation were created to avoid a “presentation sequence” bias. The face stimuli were selected from the Chicago Face Database (CFD version 2.0.2—March 2016) (Ma et al., 2015), free facial stimuli of 597 high-resolution, standardized photographs of black and white men and women of varying ethnicity (Asian, Black, Latino, White) between the ages of 18 and 40. For each face there are extensive data including both physical attributes (e.g., face width, nose shape.) as well as subjective ratings by independent judges (e.g., attractiveness, masculinity, femininity…). The database includes photographs with varying facial expressions: neutral, angry, fear, happy with closed mouth, happy with open mouth.

For our study we chose faces that were homogeneous in their ethnicity (White) and considered neutral (N) in emotional expressiveness. The average age attributed to the faces by the participants of the CFD study was 22.31, SD = 1.57, whereas the averages for attractiveness (3.37, SD = 0.67), dominance (2.40, SD = 0.55), trustworthiness (3.46, SD = 0.35), and perceived racial prototypicality (3.57, SD = 0.78) relate to a scale from 1 (not at all) to 7 (extremely), and are all relevant aspects particularly influential for our study (see Figure 1).

Four of the face stimuli extracted from the Chicago Face Database (Ma et al., 2015) considered in the study.

Male and female faces significantly differed only in age (average age, M + F = 22.31; males = 21.35, SD = 1.64; females = 23.26, SD = 0.77; t = 1,707, df = 28, p < 0.000).