404 JOHN LINCK ULRICH 



posturing to raise the latch occurred on the fourth trial, and not 

 a single imperfect response was recorded. The superiority of 

 this rat was such that an adequate explanation can not at this 

 time be given. 



One thing, however, was clearly noticeable. When in one rat 

 of a litter marked efficiency in learning the latch-box existed, 

 other members of the litter showed efficiency in this direction, 

 or the behavior of a member of the litter revealed evidence that 

 the problem might be solved; and when the solving of the prob- 

 lem did not take place in any member of a litter, the behavior of 

 only one or two members showed that the problem might be 

 solved. There is a high correlation between members of a litter 

 when the problem is effectively solved, and a low one when the 

 solving of the problem was impossible. An explanation of this 

 high and this low correlation in litters can not be attributed to a 

 difference of " intelligence' ' in rats, for no such factor can be sup- 

 posed to condition ineffective posture under the latch, and the 

 production of imperfect responses. Moreover, if " intelligence" 

 is indicated by the efficiency of the performance of movements, 

 then when the problem remained unsolved at the end of 6 days, 

 a low limit of "intelligence" or its entire absence must be assumed. 

 There is danger if such a norm as " intelligence" is accepted, that 

 this will become our chief concern, and not the conditions that 

 actually determine and do not determine the solution of the 

 problem. 



Some additional observations of the movements of rats led to 

 the belief that there exist in many rats functionally undeveloped 

 reflex mechanisms, and this led to additional experimentation 

 and tests of rats. Some idea of undeveloped integrated reflexes 

 was obtained when it was observed that posturing to produce 

 the neck reflex was difficult or impossible, and as a consequence 

 imperfect responses were produced. Observations of the be- 

 havior of rats in the problem did not determine for a certainty 

 that the reflex mechanisms were undeveloped, for the neck reflex 

 movement was produced rapidly, too rapidly in fact, for good 

 observation. 



