In the 1st experiment , the cognitive effects of experimental tonic pain of mild and moderate intensities produced by a computer-controlled pneumatic tourniquet cuff were assessed ; in the 2nd , the effects of saline solution and remifentanil were assessed in the absence of pain ; and in the 3rd experiment , the cognitive effects of moderate pain intensity relieved by remifentanil infusion were assessed followed by increasing pain to moderate intensity during a constant remifentanil infusion .