When, during monocular viewing of a picture, a person changes fixation point to an apparent nearer object, convergence of as much as a degree or two usually occurs. The magnitude of this newly discovered response (called perspective vergence), can be altered by making relatively minor changes in an illustration. The trial-to-trial reproducibility of the responses, as well as the cross-subject agreement in changes of response magnitude for a given change in stimulus in configuration will permit a systematic exploration of the kinds of stimuli in perspective illustrations which contribute to this sort of involuntary oculomotor response. Dr. James Enright will continue his studies of perspective vergence while performing psychophysical studies and making measurements of eye movements in humans. His work is directed at exploring previously unappreciated components of eye movements. Nevertheless, there is ultimately a potential for clinical appreciation as well. Correction of squint is one of the most common sorts of surgical interventions in the human visual system, and a more thorough understanding of the muscular activity associated with vergence and torsion may well eventually contribute to more efficient diagnosis and correction of muscular and nervous imbalances responsible for abnormal eye orientation.
