4 ferrets were trained to discriminate upright and inverted triangles; on transfer tests they generalized to outline figures, small figures, and isosceles triangles. After training to discriminate an upright triangle from a cross, the ferrets generalized to outline figures, rotated figures, and a background of 2-cm. striae. A number of differences in performance between ferrets and hooded rats are noted.

In Experiment 1, 8 rats were given training on maze alleys blind at 1 end and a further 8 were given training on alleys open at both ends. On standard closed field test problems, the closed alley group made fewer errors than the open alley group, but showed no shift in the relative daculty of problems permitting direct visual solution.In Experiment 2,lO rats were given standard closed field test problems (white barriers and white maze floor) and another 10 were given the same problems with black barriers and white maze floor. There were no significant differences in errors or in the relative difficulty of problems permitting direct visual solution. It was concluded that rats make negligible use of visual cues to blind alleys in the closed field test situation.

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