264 The Animal Mind 



a darkened region, to turn away and towards the light. 

 The cockroach, as is well known, prefers darkness to light : 

 Szymanski (701), however, succeeded, by giving it an 

 electric shock when it ran into the dark part of a box, in 

 educating it to turn back as soon as it reached the edge 

 of the darkened region, without waiting for the shock, 

 and Turner (729) obtained similar results. 



When an instinct is thus completely suppressed by 



'punishment, the conscious accompaniment of this modifi- 



I cation in behavior is probably simply a change in the af- 



llective tone of the situation. Instead of being pleasant, 



it becomes unpleasant. In a human being, memory ideas 



I might accompany the process : a human pike, for instance, 



I might at the sight of a minnow recall clearly the bump on 



\the nose and his consequent humiliation. But we can 



/explain the pike's behavior just as well if, in accordance 



/with Lloyd Morgan's canon, we assume merely that the 



I sight of a minnow has become unpleasant to him : he has 



lost his taste for minnows. 



r Punishment has been the means in many cases of train- 

 I ing animals to manifest their ability to discriminate be- 

 V^tween stimuli. The desired end is of course to attach the 

 [negative reaction to those features in which the "wrong" 

 stimulus differs from the "right" stimulus. For instance, 

 an animal is being taught to choose a light rather than a 

 dark passage, the two openings being side by side : when he 

 enters a dark passage he gets an electric shock. It will be 

 natural for him at first to attach the withdrawing reaction 

 consequent on the electric shock to the sight of the whole 

 apparatus. Whether he will shrink back from it or rush 

 indiscriminately into either of the passages depends on 

 the relative prepotency of his impulse to enter the pas- 

 sages and his impulse to withdraw from injury : in either 



