LIGHT DISCRIMINATION IN THE ENGLISH SPARROW 



93 



always to the brighter light, and learn to choose the darker 

 light. It took Male V 165 trials and Female VI 270 trials to 

 learn the problem. Table V shows the record made by the two 

 sparrows in learning the problem. The first column gives the 

 number of each series of 15 trials. The second and fifth columns 

 give the average percentage of error (series divided into small 



TABLE V 



Showing errors made in learning the first discrimination by the two birds which 

 were trained to choose the darker light. The middle column in each group shows the 

 percentage of errors made in each test. In the column to the left of the middle, 

 the period of learning is divided into thirds and the average percentage of error is 

 calculated for each third. In the column to the right is given the percentage of 

 error for each half of the learning period. Despite occasional lapses as shown by 

 increased percentage of error for single days, each of the later groups of days shows 

 a decided lowering of the error percentage. This shows the gradual aspect of the 

 learning process. 



groups) for Male V and Female VI respectively. The averages 

 show a decided decrease in the percentages of error made by the 

 birds during the learning of the problems. The third and sixth 

 columns show the percentage of error for the daily series of 15 

 trials each, for each of the. birds. The fourth and last columns 

 give respectively the average percentage of error for the first 



