EFFECTS OF STRYCHNINE UPON RATE OF LEARNING 



153 



differences are at least three times their probable errors and 

 therefore almost certainly the result of the differential treat- 

 ment of the two groups. In the second strychnine experiment 

 (groups E and F) the superiority of the drugged over the nor- 

 mal animals is less pronounced, amounting to only 18 per cent 

 for the first errorless run and 11 per cent for three successive 

 errorless runs. The differences also are not significantly greater 



TABLE 2 



A comparison of the number of trials required for learning by rats after injections 

 of strychnine and of water 



Differences 



* In a previous discussion of these data (Lashley, '17) a mistake was made in 

 computing the probable error of this average. The error was large but does not 

 significantly affect the conclusions of that paper. 



than their probable errors, so that from these data alone the 

 second experiment lends little support to the first. 



As has been brought out in the earlier discussion, however, 

 the drugged animals in this experiment showed in other re- 

 spects a lesser effect of the drug than did those used in the first 

 experiment. The records of the behavior of the animals of 

 group E in the maze give only two rats which showed tremor 

 after injection of strychnine and these two animals required 

 fewer trials for learning than any others in the group. It is 



