The men had been alcoholics with verifiable blackout periods occurring during the 4 preceding years. Mental status examinations of the sober subjects were within normal limits. At the start of the experiment, pulse rate, blood pressure, respiration rate, and blood alcohol concentration (BAC) were measured, and a full electroencephalogram (EEG) was administered. Each subject then drank four ounces of whisky. At 45 minute intervals, vital signs and BAC were measured, a 5-minute EEG was recorded, and the subjects were given another four ounces of whisky. After 4 hours, the subjects were returned to the ward, and their behaviour was monitored for another 6 hours. The following morning, the subjects were questioned about the events of the previous day. All subjects abruptly changed to a more angry and challenging mood between 1 1/2 and 2 1/2 hours after drinking began. Memory gaps began coincident with the time that this change in mood was noted and ranged from 2 to 7 hours. The mood change deepened during the period of memory loss and resulted in one subject becoming violent and the others reporting violent feelings. Following the abrupt change in mood, each subject narrowed his verbal production to an emotion-laden theme from his remote memory. The theme became the major component of both the change of mood and the content of the mood for the remainder of the period of memory loss and dealt with the subject's cultural identity as well as his personal identity. Thus, it appears that a blackout not only involves a short-term memory loss that is not dependent upon a subject's mental state but also brings into focus specific stored memories and determines how these memories will be dealt with in an affective manner. Knowledge of this process may be useful in predictively forestalling major acts of violence in people in whom random violence or violent feelings have been noted during blackout periods. Eleven references are included.