Various drugs and hormones were injected subcutaneously into four albino rats and their effects upon rate of response in the Skinner conditioning box studied. Sodium bromide has no effect upon mean rate of response. Adrenalin (.025 cc.) decreased the rate by 25-30%. Benzedrine in .5 mgm. dosage increased the number of responses by 142%…0375 gm. of ephedrine produced little effect upon rate…005 unit insulin given one hr. before the test increased rate of response by 26%…1 unit given one hr. previous to the test produced an increase of 19%. A combination of .005 unit insulin given one hr. and .5 mgm. benzedrine injected 15 min. before the test produced a decrease in the number of responses. This effect is variable and difficult to control. Pellets containing .033 mgm. benzedrine produced an increase above the base rate in the rate of pushing, but not so high a one as that produced by subcutaneous injection. A combination of .005 unit insulin and benzedrine pellets resulted in a mean increase in rate of 22%…011 gm. of phenobarbital injected immediately before the test had no effect, while .022 gm. given immediately before the test almost completely eliminated the responses within 10 min. (PsycINFO Database Record (c) 2006 APA, all rights reserved)