Differential Spectral Sensitivity in the Optic Tectum and Eye of the Turtle

Light flashes of calibrated wavelength and intensity were presented to the turtle eye and electrical responses were simultaneously recorded from the cornea and the optic tectum. Spectral sensitivity curves derived from criterion-response levels showed a characteristic red-sensitive process at both sites. At high criterion levels the two curves were quite similar. At low criterion-response levels the tectum showed an enhanced blue-green process not evident in the peripheral record. The sensitivity to blue-green may correspond to previously observed behavior.