A visual stimulus generator was used to display 2-D textured images on a monitor. The size of the texture components was chosen with reference to previously measured psychometric curves for detection threshold. Limits between categories differed significantly. This demonstrates the existence of two responses, one for the gradient detection and one for the edge detection. The former case suggests a filling-in phenomenon.
Preliminary results show the same tendency for contrast.
It has also been reported by the observers that the latency for detecting texture gradient was greater than for discriminating shape from texture.