Some effects of lysergic acid diethylamide on visual discrimination in pigeons

Summary Six pigeons were tested on a visual discrimination between light flickering at various frequencies and a steady light, under saline and LSD. The birds were required to respond for food rewardby pecking on the left key in the experimental box at FR35 if the light was steady, and at FR35 on the right key if the light flickered. Incorrect responses were never rewarded. Each experimental session continued until the bird obtained 60 reinforcements.The doses of LSD were 20, 40, and 80 g/kg, administered by i.m. injection. 20 g/kg produced a significant increase in accuracy of performance and the results with 80 g/kg suggest a decrement in accuracy. Depression of the rate of responding as well as periods of complete cessation of responding were found to occur in dose-related fashion. Tolerance to the rate and pause effects apparently developed over the testing period of about 10 months.This research was supported in part by USPHS Research Grants MH-03363, MH-5942-14 and MH-5942-15 from the National Institute of Mental Health.