It is expected that summation of visual system increases at dark adaptation. For spatial summation, Arden
et al. reported the result to prove this expectation. But there is no report to show directly the increase of temporal summation through dark adaptation process. In this paper, dark adaptation curves at several temporal and spatial test conditions were obtained. Results show that spatial summation increases through dark adaptation process significantly, as Arden
et al. reported. On the other hand, temporal summation does not increase through dark adaptation process, except when test field is small. It is suggested that these results can be interpreted by introducing the inhibitory mechanism of visual system.
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