48 L. W. SACKETT 



relapses learning to discriminate between the circle and the 

 square, while the success of No. 7 came suddenly in the 13th 

 series. Fearing that this was a matter of chance, the experi- 

 ment was continued, but he missed only three in the following 

 60 tests. The most marked divergence came when the ellipse 

 was paired with the circle. No. 6 required only one series and 

 there was no reason to doubt his ability as he simply looked the 

 apparatus over carefully in his first experience with it, running 

 his nose along the circumference, giving it only a passing glance 

 after that. No. 7 was completely lost with it. It was only 

 after 23 series, with numerous relapses, that he succeeded 

 at all. This difference is not easily accounted for unless 

 it be due to the fact that when No. 6 made his selection 

 his head was raised considerably so that he could see the whole 

 form at once, or at least some of its main dimensions, while 

 No. 7 approached the apparatus with his nose very close to 

 the ground in such a way that when he raised his head to inspect 

 the forms his eye would catch the base lines first. This had been 

 sufficient to enable him to discriminate between the forms before 

 but now other parts of the forms must be closely observed. 

 This explanation is given color by the fact that his success came 

 only after he had been scolded and even punished out of his 

 slovenly habits. At no time did this intrusion of the experi- 

 menter occur when the animal was making a selection. He 

 probably succeeded by virtue of a better method which gave 

 him better position and led him to give better attention and not 

 through an increase in ability. Both discriminated the rect- 

 angle after they had learned the ellipse. This indicates that 

 only the general features of the ellipse were observed and that 

 if they selected by means of the whole form the margins were 

 not distinctly seen. The hexagon had to be learned but there 

 was never any doubt that they would succeed in avoiding it. 

 It was only a matter of how long it would take them to form 

 the habit well enough to get 100% right choices in any one 

 series. A new irregular form which was half circle and half 

 hexagon was then made. When this was paired with the circle 

 it gave No. 7 no difficulty when either the hexagonal or circular 

 edge was down. No. 6 was never very doubtful about it as 

 the table indicates. The success with the hexagon-circle and 

 the failure with the circle -triangle is no doubt due to practice 



