108 EUPHA FOLEY TUGMAN 



Another question was raised. When perplexed for a long time 

 does the bird forget or unlearn the problem? The observer is 

 inclined to think that it does. 



Male IV learned to discriminate the lights when the differ- 

 ence in intensity was .017 c.p. after 225 tests. The difference 

 in intensity was decreased to .013 c.p. and he learned the dis- 

 crimination in 315 tests. The difference was again decreased 

 to .009 c.p. The bird was completely* perplexed. Each time 

 he went to the right side. 390 tests were given him but he could 

 not learn to discriminate so small a difference in intensity. The 

 variable light was shifted back so the difference in intensity 

 was .013 c.p. He had correctly discriminated this difference be- 

 fore in 315 tests. But now he continued to go every time to the 

 right side. After 360 tests the difference in intensity was again 

 increased — this time to .017 c.p. He had previously learned 

 this discrimination after 225 tests. The bird still persisted in 

 going to the right side. The observer finally decided that the 

 bird had forgotten the problem. So the difference in intensity 

 was made extremely large. The bird correctly discriminated the 

 lights in 15 tests. The lights were then shifted back to .017 

 c.p. and the bird took 240 trials in learning the discrimination 

 which had only required 225 trials in the descending series. The 

 results therefore, seem to indicate that the bird was perplexed 

 so long that he really forgot or unlearned the problem. 



Another question which suggested itself was whether or not 

 the birds would learn the position habit if the order was very 

 complicated. They soon acquired the habit of alternating from 

 right to left. A few times the experimenter observed that the 

 birds learned to go twice to one side and twice to the other and 

 three times to one side and three times to the other. These 

 latter cases might have been merely accidental. It would cer- 

 tainly be an interesting problem to try various orders and see 

 if the bird could learn them. Also, could the bird acquire the 

 position habit if it did not have the light to guide it, i.e., if the 

 lights were of equal intensity? 



The observer is very much interested in the question of whether 

 or not these periods of stubbornness or stupidity, which all the 

 birds seem to have occasionally, occur periodically. She was 

 unable to tell from the data at hand. 



