Motion perception in two different contexts
Project Completed
Project A
This was a cooperation with Drs. Werner Eisenbarth and Hans Strasburger, Generation Research Program, University of Munich, Germany.
Motion perception was used as an indicator of early effects of eye diseases in the periphery of the visual field. In particular, we investigated whether subtle defects of motion perception in patients with age-related maculopathy (ARM) can be found in regions of the retina that lie outside the macula. The results showed that such defect can indeed be found. Bottom line: Early ARM already affects areas of the retina that do not belong to the macula.
Publication:
Eisenbarth W, MacKeben M, Poggel DA, Strasburger H. (2008) Characteristics of dynamic processing in the visual field of patients with age-related maculopathy. Graefe’s Arch. Clin, Exp. Ophthal. Jan; 246(1): 27-37 (pubmed, free open access)
Abstract
Purpose. To study the dynamic visual field characteristics in age-related maculopathy (ARMD) we measured motion sensitivity, double-pulse resolution (DPR) and critical flicker fusion in 14 ARMD patients (18 eyes), age-matched controls, and young controls.
Methods. Motion stimulus was a plaid with spatial and temporal Gaussian envelope, moving in one of four directions at a constant velocity (5.7°/s) inside the Gaussian aperture. Motion contrast thresholds were determined by a 4-afc staircase algorithm on the horizontal meridian at 10°, 20°, 30°, 40°, and 60° eccentricity. DPR was measured under photopic conditions using Treutwein`s 9-fold interleaved technique (Treutwein, 1991), with stimuli positioned on concentric rings at 5°, 10°, and 20° eccentricity on the main and oblique meridians, at a total of 25 positions. CFF was measured foveally only.
Results. Motion contrast sensitivity in ARMD patients was pronouncedly reduced (0.23 – 0.66 log units, p< 0.01), not only in the macula but out to at least 20° eccentricity. In the two control groups, motion contrast sensitivity systematically declined with retinal eccentricity (0.009 – 0.032 log units/deg) and slightly with age (0.01 log units/year). Photopic double-pulse thresholds in normals were approximately constant in the central visual field and increased outside a radius of 10° (1.73 ms/deg). DPR thresholds were strongly increased in ARMD patients (by 23 –32 ms, p< 0.01) in the entire test field up to 20° eccentricity, which confirms the findings from motion sensitivity. The foveal CFF was increased in ARMD by 5.5 Hz, or 14% (p< 0.01).
Project B
This was a cooperation between Drs. Dorothé Poggel and Hans Strasburger, Generation Research Program, University of Munich, Germany.
We investigated whether relative motion can serve as a cue for sustained attention. The rationale was that in real life almost all perception of motion is produced by relative motion of stimuli on the retina. In our experiments, we used a simple perceptual task to see whether attention can help solve it. This task was direction discrimination of a static stripe pattern. Bottom line: Relative motion perception has a long latency, but it can indeed attract attention to improve discrimination performance.
Publication:
Poggel DA, Strasburger H, MacKeben M. (2007) Cueing attention by relative motion in the periphery of the visual field. Perception 36(7) 955 - 970. (pubmed)
Abstract
Sudden changes of visual stimulation attract attention. The observer’s body motion generates retinal flow field patterns containing information about his own speed and trajectory and relative motion of other objects. We investigated the effectiveness of relative motion as an attentional cue and compared it with conventional cueing by appearance of a frame in the far periphery of the visual field.
In a group of ten subjects, contrast thresholds for the perception of static Gabor grating orientation (4 ANFC task) were determined at 20°, 30°, 40°, and 60° eccentricity. Subsequently, near-threshold discrimination performance of Gabor pattern orientation without vs. with a ring-shaped cue was measured at the same positions. The same Gabor patterns were then presented embedded in a random-dot flow field, and uncued discrimination performance was compared with performance after presentation of a relative-motion cue (RMC), i.e. a small random-dot field with motion in the opposite direction of the flow field.
Both, the conventional ring cue and the RMC induced significantly increased discrimination performance at all test locations. With the parameters chosen for this study, the RMC was slightly less effective than the conventional cue, but its effects were somewhat more pronounced in the far periphery of the visual field.
Thus, relative motion is a powerful cue to attract attention to peripheral visual objects and improves performance as effectively as a conventional ring cue. The findings have practical relevance for everyday life, in particular for tasks like driving and navigation.