THE CANADIAN ENTOMOLOGIST 103 



APPERCEPTIONAL EXPPXTANCY AS A FACTOR IN 

 PROTECTIVE COLORATION. 



BY HARRY B. WEISS, NEW BRUNSWICK, N. J, 



It is a matter of common knowledge that many insects 

 escape detection by reason of their resemblance to certain sur- 

 roundings. Conotrachelus nenuphar Hbst., which drops to the 

 ground when disturbed, resembles bits of soil so closely that it 

 often escapes observation. Certain moths resemble the bark upon 

 which they rest; many caterpillars resemble the foliage upon 

 which they feed; in fact, such resemblances arc almost too 

 numerous to mention. 



• This phenomenon is known as protective coloration, and is 

 usually dismissed without further thought. Upon analyzing it 

 further, however, it is evident that other factors contribute to- 

 ward the result obtained by the perception of such an insect 

 amid such surroundings, or, in fact, any surroundings. The per- 

 ception of an insect is modified by associated perceptions from 

 adjoining surroundings. A perception of a colour received, for 

 instance, from a butterfly's wing will depend in part upon other 

 perceptions received at the same time from adjoining surroundings 

 or adjoining parts of the butterfly. 



In addition to sensation, which is the result of stimulation 

 upon the organ of sight by the object in question, perception is 

 also determined by apperception, which is the contribution of the 

 mind from previous experience. In other words, the mind also 

 contributes something which helps to form the complete mental 

 content. A red background, for instance, arouses an appercep- 

 tional expectancy for red, a green background an apperceptional 

 expectancy for green, and so on. Many green insects are rendered 

 less conspicuous and sometimes inconspicuous against a green 

 background by reason of this expectancy on the part of the ob- 

 server. Without this expectancy factor such insects would be 

 more conspicuous than they are. When a protectively coloured 

 insect is removed from its surroundings, and both surroundings 

 and insect viewed separately, the sensations are quite distinct. 



Many trained observers, and, in fact, numerous birds, are 

 able to overcome this expectancy, and as a result discriminate 



June, 1913 



