100 HAROLD C. BINGHAM 



Having found that the chicken could learn to pick up wheat 

 and avoid rice, Katz and Revesz sought to answer the question : 

 By what means does the bird discriminate between the two 

 kinds of grain? Accordingly they began to test the chicken's 

 discrimination of sizes and forms. Because the chickens could 

 be trained to eat only half -grains of rice when scattered among 

 whole grains, the authors were convinced that there was a dis- 

 crimination of size and form. A little further study leads them 

 to conclude : ' The chicken also discriminates between squares 

 and triangles. Knowledge of this fact we secured through a 

 variation of the experimental procedure. Out of green peas, 

 (some cf which had been readily eaten), we cut three and four 

 cornered pieces. On account of their moisture they could not 

 be glued down, so we laid the four sided-pieces upon a glass 

 plate and the three -sided pieces under it. The chicken found 

 that the three-sided pieces could not be reached and soon ceased 

 to peck at them. Then if we laid both forfns upon the glass 

 plate, only the squares were picked up. By means of the same 

 method we found that the chicken discriminates between trian- 

 gles and circles as well as squares and triangles." 



The study made by Katz and Revesz is open to the same 

 general objection with which this paper was opened. They 

 have, in too many cases left the reader uncertain of the exact 

 conditions. They have tried to do too much and have not 

 accomplished any one task; their report indicates carelessness 

 and indifference to details. Such work makes an interesting 

 paper. It is probably received more favorably by the majority 

 of readers than an intensive study of a problem. After all, 

 however, this sort of superficial work does not get us anywhere. 

 No doubt the statement that "the chicken also discriminates 

 between squares and triangles" and "between triangles and 

 circles as well- as squares and circles," holds true for the condi- 

 tions under which the experiment was made. But from the 

 written account one cannot tell what the conditions were. One 

 does not know, for example, the relative sizes of the different 

 forms. Were they equal in area? Was the square an inscrip- 

 tion of the circle or vice versa? Was the diameter of the circle 

 equal to the height of the square or the altitude of the triangle ? 

 These are some of the factors which must be known before one 

 can safely say that the chicken perceives form. One could 



