58 HAROLD C. BINGHAM 



threshold study would reveal a discrimination considerably 

 smaller than a 0.5 cm. difference. 



Evidently the crow's perception of size is much superior to 

 the ability of the chick in the same task. Although the experi- 

 mental setting was somewhat different in our studies, it seems 

 that they are sufficiently alike to warrant comparisons. The 

 maximum variable that my chicks were able to discriminate 

 from a standard 6 cm. circle was the same, 4.5 cm. circle, as his 

 crows discriminated from a 5 cm. circle. From the standpoint 

 of size perception, it would seem, therefore, that the ability of 

 the crow is considerably greater than that of the chick. 



