Selective changes of sensitivity after adaptation to simple geometrical figures

Using simple geometrical figures, the effect of adaptation upon sensitivity to figures of the same or different form was investigated. The adapting stimuli (blank white field, contour triangles, or circles) were presented for 1, 5, 30, or 60 sec. The test stimuli were always triangles, presented for a short exposure time at .1, .2, .4, .8, and 1.2 sec after the offset of the adapting pattern. The threshold duration of the test stimuli was measured. It was found that both adapting patterns raised the threshold above that measured for adaptation with the blank white field. But it wss only for the pair “adapting triangles-test triangles” that an increase of the time of adaptation beyond 5 sec resulted in an increase of this effect. This suggests that selective lowering in sensitivity during prolonged viewing of some figures may develop. The effect disappeared after about 1.2 sec following an exponential curve.