Alcohol and memory: Blackouts
        Blackouts represent episodes of  amnesia during which subjects are capable of participating even in salient, emotionally charged events-as well as more mundane events-that they later cannot remember (Goodwin 1995). Like milder alcohol-induced memory impairments, these periods of amnesia are anterograde , meaning that alcohol impairs the ability to form new memories while intoxicated, but does not erase memories that were formed prior to becoming intoxicated. Formal research into the nature of alcohol-induced blackouts began in the 1940s with the work of E.M. Jellinek (1946). Jellinek's initial characterization of blackouts was based on data collected from a survey of Alcoholics Anonymous members. Noting that recovering alcoholics frequently reported having experienced alcohol-induced amnesia while they were drinking, Jellinek concluded that the occurrence of blackouts is a powerful indicator of alcoholism.
       In 1969, Goodwin and colleagues published two of the most influential studies in the literature on blackouts (Goodwin et al. 1969a,b). Based on interviews with 100 hospitalized alcoholics, 64 of whom had a history of blackouts, the authors posited the existence of two qualitatively different types of blackouts. People experiencing the first type, en bloc blackouts, are unable to recall any details whatsoever from events that occurred while they were intoxicated, despite all efforts by the drinkers or others to cue recall. Referring back to our general model of memory formation, it is as if the process of transferring information from short-term to long-term storage has been completely blocked. En bloc memory impairments tend to have a distinct onset. It is usually less clear when these blackouts end because people typically fall asleep before they are over. Interestingly, even in the midst of an en bloc blackout, people appear able to keep information active in short-term memory for at least a few seconds. As a result, they can often carry on conversations, drive automobiles, and engage in other complicated behaviors. Information pertaining to these events is simply not transferred into long-term storage. Ryback (1970) said that intoxicated subjects in one of his studies "could carry on conversations during the amnesic state, but could not remember what they said or did 5 minutes earlier. Their immediate and remote memory were intact" (p. 1003). Similarly, in his study of memory impairments in intoxicated alcoholics, Goodwin (1970) reported that subjects who experienced blackouts for testing sessions showed intact memory for up to two minutes while the sessions were taking place.
      The second type of blackouts, fragmentary blackouts, as the name suggests, involve partial blockade of memory formation for events that occurred while a person was intoxicated. Goodwin and colleagues(1969a) reported that subjects experiencing fragmentary blackouts often become aware that they are missing pieces of events only after being reminded that the events occurred.  Interestingly, these reminders trigger at least some recall of the initially missing  information. Research suggests that fragmentary blackouts are far more common than those of the en bloc variety (White et al., in press; Hartzler and Fromme, 2003; Goodwin et al., 1969b).