EFFECTS OF ETHANOL ON HUMAN FREE-OPERANT COOPERATIVE RESPONDING

The effects of ethanol (0.5, 0.75 and 1.00 g/kg) on human cooperative behavior were examined. Ethanol or placebo was administered 30 min bef ore the second of five trials. During the first of two alternating sch edule components, button presses were maintained by a random interval (RI) 60-s schedule of point additions to a counter marked 'Your Earnin gs'. During the second, Choice, component a concurrent RI 60-s schedul e maintained button presses on two manipulanda. Subjects randomly assi gned to the social group were instructed that they were paired with an other person and could earn points working with or independently of th is person. Working together, the cooperative response, simultaneously produced points on counters marked 'Other's Earnings' and 'Your Earnin gs'. Working independently, the independent response produced points o nly on the counter marked 'Your Earnings'. The other person was fictit ious. The instructions for the non-social group did not mention anothe r subject and the counter marked 'Other's Earnings' was not visible bu t schedule contingencies were identical to those for the social instru ction group. For the social instructions group, 1.00 g/kg ethanol incr eased the proportion of cooperative responses and time allocated the c ooperative option. For the non-social instruction group, time allocate d to the topographically identical but non-social equivalent of the co operative response decreased at the same dose. No significant between- group effects were observed following acute administration of 0.50 and 0.75 g/kg ethanol. These results suggest that the instructions establ ished a functionally distinct social, cooperative, response which was differentially affected by ethanol.