Short term adaptation exists in the disparity vergence system exhibited by a decrease in the response dynamics

In order to survive, humans have learned to adapt to their environment. Evidence of adaptation is present in many physiological systems. This study shows the disparity vergence system also adapts to environmental conditions. Two types of step stimuli, a small stimulus of one degree and a large stimulus of four or eight degrees, were presented to subjects using a haploscope configuration. There were three phases to the experiment, beginning with a baseline phase, then adaptation, and recovery. The baseline paradigm presented only large steps. The adaptation phase presented small and large steps in a 5:1 ratio, and the recovery phase presented only large steps to ensure fatigue was not affecting the adaptation results. The goal of this study was to determine if the predominance of smaller stimuli has a dynamic affect on the larger step responses. Preliminary data show the dynamics as quantified by the main sequence of adapted responses decreases on average compared to the baseline data. Furthermore, the dynamics return to similar values as those measured during the baseline, showing fatigue was not present during the adaptation phase. This study demonstrates short term adaptation exists in the vergence system demonstrated by a decrease in the dynamics.