Visuo-Motor Adaptation to Stepwise and Gradual Changes in the Environment: Relationship between Consciousness and Adaptation
Yutaka Sakaguchi, Yu-ichi Akashi and Mitsuo Takano
University of Electro-Communications, Tokyo, Japan 1-5-1, Chofugaoka, Chofu, Tokyo 182-8585, Japan
Visuo-motor transformation in the human brain continuously adapts to the external environment, regardless of whether we are aware of the environmental change. This study examines the features of visuo-motor adaptation with stepwise and gradual visual shifts to explore the relationship between consciousness and adaptation. First, we ran psychological experiments, in which the amount of aftereffect was compared between the two kinds of visual shift. For most participants, almost complete aftereffects were observed in the gradual condition, while a slight aftereffect was observed in the stepwise condition. Interestingly, however, the magnitude of the aftereffect depended more on whether the participant noticed the visual shift than on whether the visual shift was stepwise or gradual. This suggests that participant consciousness is an essential factor in visuo-motor adaptation. Next, we built a computational model to simulate the experimental results. Its fundamental concepts were “reinforcement learning”, giving a basic strategy for r choosing an appropriate motor command; “modular architecture”, providing different visuo-motor transformations for different environments; and “reliability of the internal model”, realizing an adaptive command selection according to the progress in learning. The behavior of the proposed model was examined in numerical experiments. Some related problems are discussed in relation to the results of psychological and numerical experiments.
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