Effects of haloperidol on recall and information processing in verbal and spatial learning

1. Normal male subjects were tested with either a multi-trial word list learning test or a spatial analogue prior to administration of either 4 mg. or 10 mg. of oral haloperidol. Six hours after drug administration subjects who had previously received the verbal test were administered the spatial test, and vice versa, so for each test there was a no-drug control group, a group tested after receiving 4 mg. of haloperidol, and a group tested after a 10 mg. dose. 2. Both the verbal and spatial learning tests yield multidimensional measures of components of memory and learning, including measures sensitive to effort-demanding and more automatic information processing operations. 3. Results showed no differences for either test among the pre-drug control group and the 4 mg. and 10 mg. groups, with only one minor exception. 4. The lack of significant results cannot be attributed to insensitivity of the test instruments used, since previous studies have documented sensitivity to a number of clinical conditions and to aging. 5. Results have implications regarding clinical effects of haloperidol. A theory that links dopaminergic functioning with effortful information processing underlying memory and learning was not supported.