The sex and age effect on the capacity to detect slight facial changes in a pair of photo- graphs was evaluated in a group of people. Each pair of photographs was displayed during 1.5 s. Two treatments were used; with and without training. The former consisted of a pair of photographs that were exhibited to the person before the test like an example of the changes that could be expected to see in the trial. Men and women showed meaningful differences in the test results; women obtained higher scores indicating an upper detailed visual perception of human faces. Furthermore, age effect over perception was found, where the greater number of correct choices was presented