294 The Animal Mind 



"should the animal put the red card down if it did not fail 

 to correspond with some image he had in mind, and why 

 when he put the green up should he leave it up and go up 

 on the high box for food if the green did not correspond 

 with some image he had in mind?" It seems to the writer 

 that the supposition of an image is unnecessary, except 

 possibly in the experiments requiring discrimination of 

 sizes. It is perfectly possible, as we know from our own 

 experience, to react to one stimulus and not to another 

 without going through a comparison of the two, unless 

 the difference between them is merely one of degree. It 

 might have been possible for a human being to discriminate 

 between the larger and the smaller cards only by calling up 

 a memory image of the card not shown and comparing it 

 with the one before him ; it surely would not have been 

 necessary for him to use images in the reactions to colors, 

 forms, and tones. And if a human being, accustomed to 

 much dependence on memory ideas, could get on without 

 them here, surely a raccoon could. Even in judgments of 

 degree, all laboratory psychologists know that human 

 beings have a strong tendency to make absolute rather 

 than comparative judgments, and use memory ideas but 

 little. Better, though still unsatisfactory, evidence of 

 the use of images is furnished by the following method: 

 " Three levers were placed on the displayer. One, on being 

 raised, displayed white, another orange, another blue. 

 The plan was to display white, orange, and blue consecu- 

 tively, then to display the same blue three times. I fed 

 the animal if he climbed upon the high box on being shown 

 the series white, orange, blue, and did not feed him after 

 the series blue, blue, blue." That is, the stimulus immedi- 

 ately preceding the reaction was the same in both cases. 

 The difference lay in the foregoing stimuli. The series 



