430 STELLA B. VINCENT 



It was not determined upon what sensory basis the above 

 response was made. It may have been olfaction or vision. 

 In some experiments where sweet potato was used instead of 

 cabbage the experimenter thinks that form, size and color were 

 eliminated which leaves brightness as a possible cue. The human 

 element was always present and although the writer concludes 

 ' that the animal's basis for reaction was something else than 

 the unconscious idiosyncracies of the experimenter," the reader 

 cannot feel so sure that this was true. 



The results from the puzzle box experiments did not differ 

 in any significant way from those obtained by others with 

 different animals. 



The third attempt was to teach the animals to discriminate 

 forms. These forms were cut out of wood, and the opening 

 which was to be discriminated was the entrance to the food 

 box. The author says that they learned to discriminate the 

 circle from the other forms when presented in pairs and even- 

 tually when given with six others. There was a strong effort 

 to control this part of the work but the basis upon which the 

 choice was made was again left unsettled. The experimenter 

 was always present in these tests. 



Color tests, which formed the fourth part of the work, were 

 made by the use of food boxes covered with standard colored 

 papers. They gave negative results. 



The brightness tests which followed were more successful. 

 It appeared that the porcupine was able to discriminate a bright- 

 ness difference of about ten shades of the Nendel series of grays. 

 Observation of the behavior of the animals led to the belief that 

 one animal reacted always by choosing the black while the 

 other reacted by avoiding the white. 



In the maze tests the porcupine compared most favorably with 

 other animals. Rotating the maze caused confusion, but they 

 were able to follow the path in the dark when they had learned 

 it in the light and learning in the dark differed little from that 

 in the daylight. 



The author says: " Memory tests of the porcupine show 

 better retention where motor or kinaesthetic factors are char- 

 acteristic of the responses than where the same general motor 

 response follows a choice of sensory stimuli, i.e., ability to thread 



