Perception of coherent motion, biological motion and form-from-motion under dim-light conditions

Department of Psychology, Vanderbilt Vision Research Center, Vanderbilt University, Nashville, TN 37240, USA.
Vision Research (Impact Factor: 1.82). 12/1999; 39(22):3721-7. DOI: 10.1016/S0042-6989(99)00084-X
Source: PubMed


Three experiments investigated several aspects of motion perception at high and low luminance levels. Detection of weak coherent motion in random dot cinematograms was unaffected by light level over a range of dot speeds. The ability to judge form from motion was, however, impaired at low light levels, as was the ability to discriminate normal from phase-scrambled biological motion sequences. The difficulty distinguishing differential motions may be explained by increased spatial pooling at low light levels.

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    • "Results that are consistent with the dissociation between visual acuity and motion coherence thresholds in patients with amblyopia have also been found in observers with normal vision. For example, motion coherence thresholds are unaffected by stimulus manipulations that significantly impair visual acuity such as low lighting conditions (Grossman & Blake, 1999) and optical defocus (Trick & Silverman, 1991; Trick, Steinman, & Amyot, 1995). Furthermore, no relationship between visual acuity and motion coherence thresholds was found in a group of 2-year old children born at risk of neonatal hypoglycemia (Yu et al., 2013). "
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    ABSTRACT: Global motion processing depends on a network of brain regions that includes extrastriate area V5 in the dorsal visual stream. For this reason, psychophysical measures of global motion perception have been used to provide a behavioral measure of dorsal stream function. This approach assumes that global motion is relatively independent of visual functions that arise earlier in the visual processing hierarchy such as contrast sensitivity and visual acuity. We tested this assumption by assessing the relationships between global motion perception, contrast sensitivity for coherent motion direction discrimination (henceforth referred to as contrast sensitivity) and habitual visual acuity in a large group of 4.5-year-old children (n=117). The children were born at risk of abnormal neurodevelopment because of prenatal drug exposure or risk factors for neonatal hypoglycemia. Motion coherence thresholds, a measure of global motion perception, were assessed using random dot kinematograms. The contrast of the stimuli was fixed at 100% and coherence was varied. Contrast sensitivity was measured using the same stimuli by fixing motion coherence at 100% and varying dot contrast. Stereoacuity was also measured. Motion coherence thresholds were not correlated with contrast sensitivity or visual acuity. However, lower (better) motion coherence thresholds were correlated with finer stereoacuity (ρ=0.38, p=0.004). Contrast sensitivity and visual acuity were also correlated (ρ=-0.26, p=0.004) with each other. These results indicate that global motion perception for high contrast stimuli is independent of contrast sensitivity and visual acuity and can be used to assess motion integration mechanisms in children. Copyright © 2015. Published by Elsevier Ltd.
    Vision research 08/2015; 115. DOI:10.1016/j.visres.2015.08.007 · 1.82 Impact Factor
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    • "Another common test used for spatial perception is the “Benton judgment for line orientation” [8], in which the subjects compare straight lines oriented in different directions with a pull of reference lines and they have to find the line in the pull that matches the orientation of the line under test. Motion blindness is often tested with Random Dot Cinematograms [9], patterns of dots moving in a direction that has to be recognized by the subjects. In all these tests, the results are usually the number of items correctly addressed at the different tasks and the diagnosis is given based on this number and on a comparison with normative data. "
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    ABSTRACT: Background Higher visual functions can be defined as cognitive processes responsible for object recognition, color and shape perception, and motion detection. People with impaired higher visual functions after unilateral brain lesion are often tested with paper pencil tests, but such tests do not assess the degree of interaction between the healthy brain hemisphere and the impaired one. Hence, visual functions are not tested separately in the contralesional and ipsilesional visual hemifields. Methods A new measurement setup, that involves real-time comparisons of shape and size of objects, orientation of lines, speed and direction of moving patterns, in the right or left visual hemifield, has been developed. The setup was implemented in an immersive environment like a hemisphere to take into account the effects of peripheral and central vision, and eventual visual field losses. Due to the non-flat screen of the hemisphere, a distortion algorithm was needed to adapt the projected images to the surface. Several approaches were studied and, based on a comparison between projected images and original ones, the best one was used for the implementation of the test. Fifty-seven healthy volunteers were then tested in a pilot study. A Satisfaction Questionnaire was used to assess the usability of the new measurement setup. Results The results of the distortion algorithm showed a structural similarity between the warped images and the original ones higher than 97%. The results of the pilot study showed an accuracy in comparing images in the two visual hemifields of 0.18 visual degrees and 0.19 visual degrees for size and shape discrimination, respectively, 2.56° for line orientation, 0.33 visual degrees/s for speed perception and 7.41° for recognition of motion direction. The outcome of the Satisfaction Questionnaire showed a high acceptance of the battery by the participants. Conclusions A new method to measure higher visual functions in an immersive environment was presented. The study focused on the usability of the developed battery rather than the performance at the visual tasks. A battery of five subtasks to study the perception of size, shape, orientation, speed and motion direction was developed. The test setup is now ready to be tested in neurological patients.
    BioMedical Engineering OnLine 07/2014; 13(1):104. DOI:10.1186/1475-925X-13-104 · 1.43 Impact Factor
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    • "Psychophysical research has also uncovered a considerable number of other differences in the way we perceive OR and NOR motion. Direction discrimination thresholds (Beardsley & Vaina, 2008; Linares, Motoyoshi, & Nishida, 2012; Snowden, 1992), displacement thresholds (Lappin, Donnelly, & Kojima, 2001; Legge & Campbell, 1981; Murakami, 2004; Palmer, 1986; Sokolov & Pavlova , 2006; Whitaker & MacVeigh, 1990) and reaction times (Smeets & Brenner, 1994) are lower for OR than for NOR motion, and changes in contrast (Grossman & Blake, 1999; Shioiri et al., 2002), spatial frequency (Shioiri et al., 2002) and stimulus size (Mestre, Masson, & Stone, 2001; Murakami & Shimojo, 1996; Nawrot & Sekuler, 1990) affect OR and NOR motion perception differently . Other differences occur during binocular rivalry – if one eye is presented with an OR motion stimulus and the other with NOR motion, the former becomes the dominant percept (e.g. "
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    ABSTRACT: In two experiments, we demonstrate a misperception of the velocity of a random-dot stimulus moving in the presence of a static line oriented obliquely to the direction of dot motion. As shown in previous studies, the perceived direction of the dots is shifted away from the orientation of the static line, with the size of the shift varying as a function of line orientation relative to dot direction (the statically-induced direction illusion, or 'SDI'). In addition, we report a novel effect - that perceived speed also varies as a function of relative line orientation, decreasing systematically as the angle is reduced from 90 to 0°. We propose that these illusions both stem from the differential processing of object-relative and non-object-relative component velocities, with the latter being perceptually underestimated with respect to the former by a constant ratio. Although previous proposals regarding the SDI have not allowed quantitative accounts, we present a unified formal model of perceived velocity (both direction and speed) with the magnitude of this ratio as the only free parameter. The model was successful in accounting for the angular repulsion of motion direction across line orientations, and in predicting the systematic decrease in perceived velocity as the line's angle was reduced. Although fitting for direction and speed produced different best-fit values of the ratio of underestimation of non-object-relative motion compared to object-relative motion (with the ratio for speed being larger than that for direction) this discrepancy may be due to differences in the psychophysical procedures for measuring direction and speed.
    Vision research 08/2013; 92. DOI:10.1016/j.visres.2013.08.010 · 1.82 Impact Factor
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