RONALD E. MYERS 489 



Hiir failed to show any evidence of transfer of discrimination Ill-ab 

 from the left eye to the right; however, tests of transfer of discrimination 

 V-ab from the right eye to the left showed a performance better than 

 chance (28 40). Figural equivalence effects may again have accounted for 

 the partial transfer although these figures have not been tested in this 

 respect. That the apparent transfer was due to effects other than a central 

 neural intercommunication was strongly indicated, however, by the great 

 ease with which Hiir was thereafter taught the inverse discrimination V-ba 

 with the untrained left eye. Cat Miiiiii has also evidenced no cross inter- 

 ference after corpus callosum section when the two eyes were separately 

 taught inverse discriminations (Ill-ab and Ill-ba). 



The considerations just described led to the conclusion that the apparent 

 transfer of the learned responses between the eyes seen in the instances 

 of Bj^'N' and Hfir and the depression of performance below a chance level 

 seen in the instance oiBrd were related not to the contribution of a com- 

 missural linkage other than the corpus callosum between the brain halves 

 but to figural generalization effects arising from similarities between 

 patterns of the separate discriminations taught the separate eyes. 



From the foregoing experiment it is clear that the cross-availability of 

 information between the two hemispheres in regard to the significance of 

 complex visual pattern stimulation occurs through the corpus callosum. 

 In the absence of corpus callosum visual learning and recall may occur 

 independently in the two hemispheres given independent sensory stimula- 

 tion. One hemisphere, under the circumstances, may support learned 

 visual responses conflicting completely with responses subsumed by the 

 other hemisphere without cross-interference. 



Subsequent work (Sperry, Stamm and Miner, 1956) has shown that 

 cats with optic chiasma and corpus callosum sectioned must relearn anew 

 with one eye pattern discriminations learned with the other eye, the 

 curves of relearning through the 'untrained' eye tending to reduplicate 

 even in detail the learning curves obtained during initial learning through 

 the 'trained' eye. This latter experiment tends to further accentuate the 

 interpretation that no information leaks across the mid-line relative to 

 visual pattern discriminative learning in the absence of corpus callosum. 



PROBLEM in. TO WHAT EXTENT DOES GNOSTIC INTERCOMMUNICATION 

 RESULT IN CONTRALATERAL MEMORY TRACE ESTABLISHMENT? 



During the monocular training in the chiasma-sectioned cat, a stable 

 and lasting change is induced in the 'trained' hemisphere receiving the 



