Abstract
Introduction It is now nearly 100 years since Frithiof Holmgren placed recording electrodes on an eye and discovered that a momentary change in potential accompanies the: reaction of the eye to light. The electrical response that he found paralleled subjective aspects of vision in several ways. Research since Holmgren's time has been directed toward fuller exploration of these parallels. The electroretinogram, or ERG, has proved to be a complex phenomenon. The search still continues for ways in which aspects of the responses may be used as objective indices of visual processes. For the physiologist this electrical behavior is interesting both for itself and for what it reveals of neural activity within the eye. To the psychologist there occurs the hope that it may enable him to bypass some of the tortuous paths of psychophysics. And to the clinician the ERG presents itself as a possible means of diagnosing particular functional