Motivational Effects of Alcohol on Memory Consolidation and Heart Rate in Social Drinkers

Several studies have documented the retrograde facilitation of memory by alcohol, but the mechanisms responsible for this curious effect are unknown. In an experiment designed to complement previous studies on incidental learning, social drinkers (men aged 18 to 30; n= 44) took part in an experiment examining the effects of alcohol on intentional learning of emotionally salient verbal stimuli. Learning occurred when participants were sober. Alcohol or placebo (1.0 vs. 0.1 ml/kg) was consumed after learning, and memory was tested, sober, 24 hr later. Compared with placebo, alcohol modestly enhanced recall of positive but not negative stimuli. Furthermore, results suggest that the reinforcing effects on memory for positive (relative to negative) stimuli occurred in association with acute psychomotor stimulant effects during the ascending limb of the blood alcohol curve. The present finding that alcohol appeared to enhance intentional learning in association with its incentive effects contrasts results from previous studies, demonstrating that alcohol appears to enhance incidental learning by memory mechanisms independent of its incentive effects. These findings support a theory of alcoholism that is based on motivational systems.