The effects of flicker-rate (0 to 24 cps) on rotary tracking performance and physiological “indicants” of activation level were studied under two conditions of background illumination (illuminated and non-illuminated). During the illuminated condition the target was visible between flashes (continuously), whereas during the non-illuminated condition it was visible only during the flash. Muscle tension of the neck and forearm flexor muscles, skin conductance, and heart rate were used as indicants of activation level. Tracking performance varied significantly with flicker-rate and illumination level. During the illuminated condition, performance decreased then increased as flicker-rate increased, the low point being at about 9 cps. During the non-illuminated background condition, performance increased rapidly as flicker-rate was increased up to 9 cps. Further increases had relatively slight effects on tracking performance. The physiological indicants remained essentially constant when flicker-rate was varied, indicating no change in activation level. The performance data were interpreted in terms of a “psychological moment” model.
The Wandering Circles: A flicker-rate and contour dependent motion illusion