Figure 1.
Effect of skin redness and blood colour on apparent health of faces.
(A) Untransformed image and images pair showing low (−) and high (+) endpoints of oxygenated and deoxygenated blood colour transforms. (B) Participants increase deoxygenated and oxygenated blood colour to optimise healthy appearance. Initial facial redness (a*) correlates with oxygenated (r = −0.911; p<0.001; R2 = 0.83) and deoxygenated (r = −0.831; p<0.001; R2 = 0.69) blood colour change applied to optimize health appearance. (C) Endpoints of the two-dimensional oxygenated versus deoxygenated blood colour transform. (D) Two-dimensional colour transform applied to optimize healthy appearance (ΔE mean±SE). (E) Regression lines relating initial face redness to deoxygenated colour change applied to optimise healthy appearance for each participant. (F) Regression lines relating initial face redness to oxygenated colour change applied to optimise healthy appearance for each participant.
Figure 2.
Effect of skin colour on apparent health of faces of various ethnicity.
(A) Untransformed image and image pair showing endpoints of skin redness transform (±16 units on the CIELab a* axis). Images shown are composites of many faces. Stimuli used were photographs of real individuals. (B) Participants increase redness to optimise healthy appearance of faces. Initial facial redness correlates with redness change applied to optimize healthy appearance (r = −0.832; p<0.001; R2 = 0.69). Different coloured symbols represent different ethnic groups of faces. (C) Regression lines relating initial face redness to redness change applied to optimise healthy appearance for each individual participant. (D) African participants increase redness in black faces more than other faces. Both African and UK-based participants increase redness in all three ethnic group faces to optimise healthy appearance.