Heading judgement from second-order motion.

M Hanada; Y Ejima

doi:10.1016/s0042-6989(00)00186-3

Home/Archive/PubMed

PubMed · 11058731

Heading judgement from second-order motion.

M Hanada·Y Ejima

View original source ↗Export metadata ↓

Abstract

We examined human heading judgement from second-order motion which was generated by random-dots with the contrast polarity determined randomly on each frame. It was found that human observers can judge heading fairly accurately from second-order motion when pure translation is simulated or when self-motion toward a ground plane with gaze rotation is simulated but they cannot when self-motion toward cloud-like random dots with gaze rotations is simulated. It is suggested that the human visual system cannot decompose the flow fields into rotational and translational components by using second-order motion information alone, but it can do in some ways from the flow field of the ground plane.

Explore related subjects

Contrast Sensitivity Humans Motion Perception Orientation Psychophysics Pursuit, Smooth Regression Analysis Comparative Study Journal Article Research Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

M Hanada, Y Ejima. 2000. Heading judgement from second-order motion.. https://doi.org/10.1016/s0042-6989(00)00186-3

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2002

High temporal frequency synchrony is insufficient for perceptual grouping.

We used textures of randomly moving grating patches to assess the role of fine-grain temporal synchrony in texture segregation. In the target area, patches reversed direction simultaneously. In the surround, patches changed direction at random times. Thus, phase changes in the target area were precisely synchronous, whereas those in the surround were not. In agreement with work carried out by Lee and Blake, we found that the target area was frequently visible, and that observers could discriminate its shape (horizontal versus vertical) at frame rates of 100 Hz in brief exposures (200 ms). Further experiments suggested that the length of unidirectional motion sequences in the target area, rather than synchrony, determined its visibility. To eliminate completely contrast and motion cues, we made all the background elements identical to the target elements, but with a random starting phase. Despite the presence of synchrony in the target area but not the background, the target was generally very hard to see. Targets that remained visible contained low temporal frequency modulations of direction. We conclude that the human observer can detect synchrony, but only at modest temporal frequencies once motion and contrast artefacts have been eliminated.

Contrast Sensitivity↗

PubMed2002

Effect of spatial waveform on apparent spatial frequency.

We examined the effect of spatial waveform on the perceived spatial frequency of a grating target. The luminance profile of 0.5 c/ degrees sinusoidal gratings was modified by either compressive or expansive power functions, and was presented alternately with a true sinusoidal grating. Subjects matched the apparent spatial frequency of the two gratings using a method of adjustment. Both compressive and expansive power functions lowered the perceived spatial frequency of the grating, irrespective of the stimulus contrast. Rectified sine wave gratings were also found to reduce apparent spatial frequency. The magnitude of the spatial frequency shifts with spatial waveform diminished with successive matches, which may represent a change in matching strategy employed by observers. Calculations and a further experiment suggest that judgements of spatial frequency may in part be determined by the separation between edges in a grating.

Contrast Sensitivity↗

PubMed2002

Perceptual grouping in the Ternus display: evidence for an 'association field' in apparent motion.

We present psychophysical experiments designed to reveal the role of facilitative contour interactions (the so-called 'association field') in apparent motion. We use the Ternus display (a trio of horizontally aligned elements oscillating in apparent motion). This display is perceived in 'element' motion when interframe intervals (IFIs) are short, and in 'group' motion when IFIs are long. Using Gabor elements arranged collinearly or in parallel, IFI is varied to find group motion thresholds. Consistent with a role for collinearity in perceptual grouping, thresholds are lower for collinear displays. The collinear vs. parallel comparison is made while manipulating contrast, spatial frequency, eccentricity, phase, orientation jitter and element separation. Results show a clear effect of contrast not observed in lateral masking paradigms or in 'pathfinder' stimuli, with higher contrast promoting within-frame grouping, and evidence of facilitatory interactions among parallel elements (although over a smaller scale). The tendency for collinear displays to group more than parallel displays declined with eccentricity with no clear difference evident at 12 deg. These changes in group motion thresholds indicate changing association strengths among the elements and is accounted for in terms of an association field. Alternative accounts in terms of second-order collector units or visible persistence are considered but are not supported by the data.

Contrast Sensitivity↗