Smooth and sampled motion

• Published in: Vision research (Oxford) Vol. 26; no. 4; pp. 643 - 652
• Main Authors: Burr, David C., Ross, John, Morrone, M.Concetta
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1986; Elsevier Science
• Subjects: Biological and medical sciences; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Humans; Motion Perception - physiology; Pattern Recognition, Visual - physiology; Photometry; Sensory Thresholds - physiology; Space life sciences; Time Factors; Vertebrates: nervous system and sense organs; Vision Stroboscopic motion Sampling Sinusoidal gratings Apparent motion; Vision Stroboscopic motion Sampling Sinusoidal gratings Apparent motion; Human; Spatial frequency; Motion; Discrimination; Stroboscopy; Vision; Contrast
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/0042-6989(86)90012-X

Stroboscopic or sampled motion is indistinguishable from smooth motion if the frequency of sampling is sufficiently high. We report measurements of the minimum sample frequency for smooth motion of drifting sinusoidal gratings (extended and truncated) which varied in spatial frequency from 0.06 to 24c/deg, in temporal frequency from 1.5 to 24 Hz and in contrast from 3 to 100 times detection threshold. Threshold sampling frequency for smoothness increased with temporal frequency and contrast, and inversely with spatial frequency. The threshold step size associated with the sampling frequency ranged from 20′' arc (for gratings of 24 c/deg) to 6 deg (for gratings of 0.06 c/deg). Calculations of the spurious frequencies introduced by sampling lead us to conclude that motion appears smooth provided that sampling is above the Nyquist limit and that the amplitude of the spurious components is below their independent threshold.