STUDIES OF CEREBRAL FUNCTION IN LEARNING, VII 



19 



THE EFFECT OF OCCIPITAL LESIONS UPON THE INITIAL 

 FORMATION OF A VISUAL HABIT 



The animals in group A were given initial training in visual 

 discrimination after lesions in the occipital region varying 

 in extent from 3.1 to 43.9 per cent of the neopallium. The 

 average amount of destruction in the group was 17.9 ±: 0.9 

 per cent. The total series (figs. 1 to 48) covers every part of 

 the occipital third of the cortex. The total extent of injury 

 in these cases is shown in text figure 1. 



The training records of group A are summarized in table 2. 

 The forty-eight animals required an average of 121.9 ±: 4.5 



Text fig. 1 Composite diagram made by superimposing the diagrams of the 

 lesions for cases 1 to 48, group A, showing that every part of the occipital third 

 of the cerebrum was destroyed in one or another of these animals. 



trials for learning and made an average of 39.1 ±: 1.6 errors 

 during training. For comparison with these figures, the 

 learning rates of unoperated animals trained under the same 

 conditions are given in table 3, columns 3 and 4. These nor- 

 mal animals required an average of 128.2 ± 5.2 trials for 

 learning and made an average of 41.8 ±: 2.5 errors during 

 training. The differences between the normal and operated 

 groups are given below. 



