E. GARCIA-AUSTT, J. BOGACZ AND A. VANZULLI 623 



40 minutes of exposure. I would like to know the relation between what you call 

 habituation and fatigue. 



Garcia-Austt. As to Dr Jouvet's remarks I must say that all subjects were given 

 careful instructions beforehand, so that, throughout the experiment, they kept 

 looking at the stroboscope. It is very unlikely that the diameter of the pupil should 

 play an important role as the eyes were fixed on the stroboscope, stimulation was 

 alwavs rhythmic and at constant frequency throughout the experiment. Conse- 

 quently illumination remained unchanged. The flash intensity was supra-maximal 

 for any given pupillary diameter. 



In answer to Dr Berger's questions, we worked with frequencies of 0.5-5/sec. 

 which are very far from the fusion frequency. Between this range we did not fmd 

 variations in the initial component of the evoked response. However, the after- 

 discharge was not observed at 4-5 sec. Of course, it is not a question of fatigue. It 

 should be mentioned that through association with other stimuli, a response may 

 be habituated or dishabituated and this occurs without any interruption or changes 

 in the flicker frequency. 





