Lines and Gabor functions compared as spatial visual stimuli

Foveal discrimination thresholds were measured for orientation, vernier alignment, bisection, displacement detection and stereoscopic acuity using simple line stimuli and also sinusoidal grating patches with gaussian intensity modulation (Gabor stimuli). Stimulus parameters such as luminance, exposure duration, component separation and, as far as possible, length were identical for both. Orientation discrimination as a function of length is almost identical for the two classes of stimuli, some observers performing slightly better with Gabor patches. Thresholds for displacement detection are also the same. Vernier, stereo and bisection acuities, however, are considerable better with line than with Gabor stimuli.