PATTERN-DISCRIMINATION IN VERTEBRATES 



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ceding this test I had required him to choose a field each stripe 

 on which was 0.312 mm. wide, and to reject a field each stripe 

 on which was 0.284 mm. wide. He chose correctly in 48 out 

 of 50 trials. In this control test I presented the 0.284 mm. 

 system ten times with a system each member of which was 

 0.312 mm. wide, and ten times with a system each member of 

 which was 0.260 mm. wide. The animal was required to choose 

 the coarser system at each trial, thus choosing the 0.284 mm. 

 system ten times and rejecting it ten times in the same daily 

 series. The results are shown in table 3. 



The animal was punished for choices 17 and 18. He had 

 usually shown a preference for the left-food-compartment. In 

 trials 17, 18, 19, and 20 he inspected the left field only. The 

 field presented on that side at these trials was the field which 

 he had correctly chosen in trials 14, 15 and 16. At trials 1 to 

 16, inclusive, he inspected both fields before choosing, and in 

 every case he selected the relatively coarser system, regardless 

 of the absolute width of its members. I believe that this animal 

 could have been adapted by training to study by the standard 

 method of right and wrong cases. Chick 2 gave no such promise. 



