2 Animal Intelligence 
ness. ‘Imitation,’ ‘invention’ and ‘practice’ almost 
inevitably refer to behavior observed from the outside. 
‘Perception,’ ‘attention,’ ‘memory,’ ‘abstraction,’ ‘rea- 
soning’ and ‘will’ are samples of the many terms which 
illustrate both ways of studying human and animal 
minds. That an animal perceives an object, say, the sun, 
may mean either that his mental stream includes an aware- 
ness of that object distinguished from the rest of the visual 
field; or that he reacts to that object as a unit. ‘Atten- 
tion’ may mean a clearness, focalness, of the mental state ; 
or an exclusiveness and devotion of the total behavior. It 
may, that is, be illustrated by the sharpness of objects 
illumined by a shaft of light, or by the behavior of a cat 
toward the bird it stalks. ‘Memory’ may be conscious- 
ness of certain objects, events or facts; or may be the per- 
manence of certain tendencies in either thought or action. 
‘To recognize’ may be to feel a certain familiarity and 
surety of being able to progress to certain judgments about 
the thing recognized; or may be to respond to it in cer- 
tain accustomed and appropriate ways. ‘Abstraction’ may 
refer to ideas of qualities apart from any consciousness of 
their concrete accompaniments, and to the power of having 
such ideas; or to responses to qualities irrespective of their. 
concrete accompaniments, and to the power of making such 
responses. ‘Reasoning’ may be said to be present when 
certain sorts of consciousness, or when certain sorts of 
behavior, are present. An account of ‘the will’ is an 
account of consciousness as related to action or an account 
of the actions themselves. 
Not only in psychological judgments and psychological 
terms, but also in the work of individual psychologists, 
this twofold content is seen. Amongst writers in this 
country, for example, Titchener has busied himself almost 
