DISCRIMINATIVE ABILITY OF THE TURTLE 21 



cent of the entrances were correct. The box with i mm. lines 

 was then faced with boards bearing 2 mm. lines and a grade of 

 94 per cent correct was made in fifty trials. In this series the 

 4 mm. lines still indicated the food box while 2 mm. lines marked 

 the electric box. The 4 mm. lines were next exchanged for a 

 series 3 mm. wide, so that the problem before the turtle was to 

 choose between two boxes bearing lines on their faces which 

 differed but i mm. in width. The 3 mm. lines were on the food 

 box, the 2 mm. on the electric box. The first fifty trials of 

 this combination resulted in 82 per cent of the choices being 

 correct and the next fifty trials of the same problem resulted 

 in a grade of 92 per cent correct. 



As will be noticed, the changes of line width were alternated 



TABLE 10 



Turtle No. 10, Discrimination 

 Between Lines of Dif- 

 ferent Width 



Lines 8, 4 and 3mm. were on the food 

 box. All lines vertical 



Lines 8mm. and 1mm. wide Lines -imm. and 2mm. ivide 



Test Right Wrong Test 



1 2 8 1 



2 3 7 2 



3 6 4 3 



4 9 11 4 



5 9 11 5 



6 12 8 



7 16 4 47 3 



8 18 2 =— - 



9 10 



10 9 1 Lines Snun arui 2mm. wide 



11 8 2 1 6 4 



12 9 1 2 9 1 



13 10 3 :.::: s 2 



14 10 4. 9 1 



15 10 5 9 1 



141 59 41 



Lines 4mm. and 1mm. ivide Lines 3mm. and 2mm. wide 



1 8 2 1 10 



2 10 2 9 1 



3 10 3 10 



4 10 4 9 1 



5 10 5 8 2 



48 2 46 



