Table 1.

The relationship between age and luminance (L^*) or color (a^*, b^*) contrast for the 4 groups of faces.

Feature	Contrast	Caucasian			Chinese			Latin American			South African
		R	P-value	Direction	R	P-value	Direction	R	P-value	Direction	R	P-value	Direction
Brow	L*	−0.50	<0.05	Decrease	−0.33	<0.05	Decrease	−0.49	<0.05	Decrease	−0.21	<0.05	Decrease
	a*	−0.27	<0.05	Decrease	0.21	<0.05	/	−0.06	ns	/	−0.36	<0.05	Decrease
	b*	−0.23	<0.05	Decrease	0.08	ns	/	−0.11	ns	/	−0.26	<0.05	Decrease
Eyes	L*	−0.11	<0.10	Decrease	−0.09	ns	/	−0.13	<0.10	Decrease	−0.25	<0.05	Decrease
	a*	−0.32	<0.05	Decrease	−0.10	ns	/	−0.30	<0.05	Decrease	−0.46	<0.05	Decrease
	b*	−0.24	<0.05	Decrease	−0.18	<0.05	Decrease	−0.17	<0.05	Decrease	−0.40	<0.05	Decrease
Mouth	L*	0.03	NS	/	0.21	<0.05	Increase	0.14	<0.10	Increase	0.18	<0.05	Increasea
	a*	−0.292	<0.05	Decrease	−0.35b	<0.05	Decrease	−0.34b	<0.05	Decrease	0.23c	<0.05	Decrease
	b*	0.16	<0.05	Increase	0.28	<0.05	Increase	0.06	ns	/	−0.06	ns	/

^aThe L^* mouth contrast of South African faces decreased until around 40 years old but then increased with age.

^bThe a^* mouth contrast was analyzed in absolute value for the Caucasian, Chinese and Latin American faces, because it had negative values for all these faces.

^cThe a^* mouth contrast of South African faces had positive and negative values according to the face; the slop of the correlational line increased when the age increased but in a negative value range (so closer to 0 in older faces than in younger faces). The aspects of contrast that decreased with age in the 4 groups of faces are highlighted in dark gray, and the aspects of contrast that decreased with age in 3 of the 4 groups of faces are highlighted in light gray.