Symptoms of prosopagnosia in intoxicated subjects.

Two experiments were made to test whether a blood ethanol concentration of about 1 g ethanol per kg blood influences the ability to recognize faces which were shown 24 hours earlier. 18 subjects who saw the faces for the first time when sober and whose task it was to recognize the faces when under the influence of alcohol, recognized the faces significantly less frequently than controls. The controls saw the faces for the first time when sober and their task was to recognize the faces later when also in a sober state. When 20 sober subjects had to recognize faces which they had seen 24 hours earlier under the influence of alcohol, they recognized the faces significantly less frequently than controls. 18 subjects to whom visual forms were shown when under the influence of alcohol and who had to recognize these forms 24 hours later when sober again performed like subjects who had to recognize faces under identical experimental conditions. Subjects who saw the forms, however, in a sober state and who had to recognize these forms when intoxicated performed significantly better than subjects who had to recognize faces under identical experimental conditions. In additional experiments, it was shown that alcohol did not influence ability to compare simultaneously presented faces. Intoxicated subjects' reduced abilities to recognize faces is regarded as a symptom of prosopagnosia since it cannot be explained by a reduced ability to recognize forms or to compare faces.