94 



CHARLES A. COBURN AND ROBERT M. YERKES 



TABLE 4 



Daily Series and Averages with Ratios of Correct to Incorrect 



First Choices 



Crow Number 3 



Problem 1a 



Crow Number 4 



RESULTS, PROBLEM 2 



Our second problem, which we arranged as a more difficult 

 one than the first, proved for the crows much more difficult 

 than we had expected. It may be described as the problem of 

 the second door at the left. The series of ten settings for this 

 problem is as follows: 



Problem 2. Second door at the subject's left to be chosen 



Settings Doors open No. of doors open No. of right door 



1 7.8.9 3 8 



2 6.7.8.9 4 7 



3 2.3.4.5.6.7 6 3 



4 4.5.6.7 4 5 



5 1.2.3.4.5.6 6 2 



6 5.6.7.8.9 5 6 



7 1.2.3.4.5.6.7.8.9 9 2 



8 3.4.5.6.7.8 6 4 



9 7.8.9 3 8 



10 2.3.4.5 4 3 



