Dynamic contrast sensitivity: methods and measurements

A portable device was constructed which presents moving, computer generated, sine-wave grating slide projections that range in spatial frequency from 0.4 to 20.5 cycles per degree. At each of two different testing sessions, the contrast sensitivities of 60 undergraduate psychology majors were measured at a static, 25 deg/sec, and 50 deg/sec target movement condition. The results indicate that as target velocity was increased, contrast sensitivity decreased at middle and high spatial frequencies but that contrast sensitivity was enhanced at very low spatial frequencies by target movement. Also, the area of peak sensitivity shifted toward lower spatial frequencies as target velocity increased. In addition, test, re-test reliability was demonstrated. The results are consistent with previous Dynamic Visual Acuity (DVA) research which has shown that the ability to resolve fine detail decreases as target velocities increase, presumedly due to limitations in eye movement control. The testing device, which was designed and constructed for the present study, has proven to be a reliable means for measuring dynamic contrast sensitivity (DCS) and has some distinct advantages over existing methods for measuring both DVA and DCS and, as such, will be valuable in future DVA and DCS research.