WorldCat Identities

Fahle, Manfred

Works: 15 works in 51 publications in 2 languages and 1,983 library holdings
Roles: Author, Editor
Classifications: QP408, 612.82
Publication Timeline
Publications about  Manfred Fahle Publications about Manfred Fahle
Publications by  Manfred Fahle Publications by Manfred Fahle
Most widely held works by Manfred Fahle
Perceptual learning ( )
9 editions published in 2002 in English and held by 1,626 WorldCat member libraries worldwide
The neuropsychology of vision ( Book )
10 editions published in 2003 in English and held by 290 WorldCat member libraries worldwide
Describes a range of exciting new approaches to neuropsychological investigation and provides a broad overview of visual neuropsychology. The book starts by examining the neural basis of perception - presenting important new research using single-unit recordings. It then considers disturbances of visual perception such a agnosia, neglect, blindsight, and achromatopsia, describing what we now know about recovery and rehabilitation from cerebral visual disorders. Throughout, the book refers to new and adapted techniques for measuring brain activity, including multi-unit sum potential recording, fMRI, and transranial magnetic-stimulation. With contributions from leading scientists in the vision sciences, it provides a state-of-the-art review of the topic
Binokulares Einfachsehen : Zur Bedeutung von Konturendominanz und binokularem Wettstreit by Manfred Fahle ( Book )
5 editions published in 1981 in German and Undetermined and held by 18 WorldCat member libraries worldwide
Sinnesphysiologie der "Überauflösung" : Wahrnehmung jenseits des Photorezeptoren-Durchmessers by Manfred Fahle ( Book )
2 editions published in 1991 in German and held by 15 WorldCat member libraries worldwide
Computation of texture and stereoscopic depth in humans by Manfred Fahle ( Book )
3 editions published in 1989 in English and held by 5 WorldCat member libraries worldwide
The computation of texture and of stereoscopic depth is limited by the eyes and by the subsequent stage of visual system in humans, and by the quality of the optical 'front end' as well as by the computational hard- and software in machines. The quality of the optics and the resolution of the opto- electronic transducer (e.g. the retina) limit spatial resolution, and , consequently, the discrimination of textures. In stereoscopic depth, thresholds far below the grain of the input-device (in humans: the photoreceptor diameter) can be attained. This extreme accuracy in locating a stimulus, called hyperacuity, is due to interpolation between the positions of the input elements, such as the photoreceptors in humans. Interpolation is most likely a feat achieved by the visual cortex, depending on a good signal-to-noise ratio of the stimulus representation. Again, resolution and contrast modulation are critical factors
A model for rivalry between cognitive contours by Manfred Fahle ( Book )
3 editions published in 1990 in English and held by 5 WorldCat member libraries worldwide
This report describes research done within the Artificial Intelligence Laboratory and the Center for Biological Information Processing (Whitaker College) at the Massachusetts Institute of Technology E25-201 Cambridge, Massachusetts 02139, USA and at the Department of Neuroophthalmology of the University Eye Clinic in D7400 Tubingen, West Germany. The interactions between illusory and real contours have been investigated under monocular, binocular and dichoptic conditions. Results show that under all three presentation conditions, periodic alternations, generally called rivalry, occur during the perception of cognitive (or illusory) triangles, while earlier research had failed to find such rivalry (Bradley and Dumais, 1975). With line triangles, rivalry is experienced only under dichoptic conditions. A model is proposed to account for the observed phenomena
Limits of precision for human eye motor control by Manfred Fahle ( Book )
3 editions published in 1989 in English and held by 4 WorldCat member libraries worldwide
If the two segments of a vernier targe are presented to different eyes, i.e., dichoptically, thresholds are three to four times higher than with presentation to the same eye. This increase in thresholds is mainly due to uncorrelated movements of both eyes, such as tremor and drifts, that occur even under steady fixation. The psychophysically measured thresholds allow one to calculate an upper estimate for the amplitudes of uncorrelated eye movements during fixation. This estimate matches the best results from direct eye position recording, with the calculated mean amplitude of eye tremor corresponding to roughly one photo-receptor-diameter. The combined amplitude of both correlated and uncorrelated eye movements was also measured by delaying one segment of the vernier relative to its partner under monocular or dichoptic conditions. Fixation proved to be relatively stable, and trained observers could sustain eye position within a few arcmin. Keywords: Hyperactivity. (KR)
Synthesis of visual modules from examples : learning hyperacuity by Tomaso Poggio ( Book )
3 editions published in 1991 in English and held by 4 WorldCat member libraries worldwide
For any given visual competence, it is tempting to conjecture a specific algorithm and a corresponding neural circuitry. It has been often implicitly assumed that this machinery may be hardwired in the brain. This extreme point of view, if taken seriously, amy quickly lead to absurd consequences. The underlying reason for the spectacular performance of human subjects in these tasks is that the information sampled by the photoreceptors and relayed to the brain does contain the information necessary for precise localization of image features, since the spacing between photoreceptors and the eye's optics satisfy (in the fovea) the constraints of the sampling theorem. More specifically, it has been shown that, in principle, spatial mechanisms that account for grating resolution are sensitive enough to support hyperacuity-level performance. Furthermore, some of the hyperacuity tasks can be solved by detecting 'secondary' cues such as luminance difference (as in the bisection task) or orientation (as in the detection of vertical vernier stimuli). The detailed structure of the neural circuitry that subserves the detection of these cues, or hyperacuity performance in other tasks is, however, unknown
Parallel computation of vernier offsets, curvature, and chevrons in humans by Manfred Fahle ( Book )
2 editions published in 1989 in English and held by 3 WorldCat member libraries worldwide
A vernier offset is detected at once among straight lines, and reaction times are almost independent of the number of simultaneously presented stimuli (distractors), even if absolute orientation cues are masked by varied orientation of the verniers. This result implies that the human visual system processes vernier offsets in parallel. Reaction times for identifying one straight target among offset verniers, on the other hand, increase with the number of stimuli. The same is true for the identification of a vernier offset to one side among verniers offset to the opposite side, if absolute orientation cues are masked. These tasks require serial or semi-parallel processing. Chevrons and curved targets show the same pattern of results. Even deviations below a photoreceptor diameter can be detected at once. The visual system thus attains positional accuracy below the photoreceptor diameter simultaneously at different positions. I conclude that deviation from straightness, or change of orientation, is detected in parallel over the visual field. Discontinuities or gradients in orientation may represent an elementary feature of Parallel processing, Human psychophysics, Hyperacuity, Early vision
Fast perceptual learning in visual hyperacuity by Tomaso Poggio ( Book )
2 editions published in 1991 in English and held by 3 WorldCat member libraries worldwide
In particular, we show that fast stimulus-specific learning indeed takes place in the human visual system and that this learning does not transfer between two slightly different hyperacuity tasks."
Disparity gradients and depth scaling by Massachusetts Institute of Technology ( Book )
3 editions published in 1989 in English and held by 2 WorldCat member libraries worldwide
The binocular perception of shape and of depth relations between objects can change considerably if the viewing direction is changed only by a small angle. We explored this effect psychophysically and found a strong depth reduction effect for large disparity gradients. The effect is found to be strongest for horizontally oriented stimuli, and stronger for line stimuli than for points. This depth scaling effect is discussed in a computational framework of stereo based on a Baysian approach which allows to integrate information from different types of matching primitives weighted according to their robustness. Keywords: Stero; Artificial intelligence; Computer vision; Depth scaling; Disparity gradients; Computational vision
On the shifter hypothesis for the elimination of motion blur by Manfred Fahle ( Book )
2 editions published in 1990 in English and held by 2 WorldCat member libraries worldwide
This result cannot be easily reconciled with the hypothesis of 'shifter circuits'."
Wie kommen Bilder in das Gehirn? : die Sicht der Hirnforschung ( )
1 edition published in 2007 in German and held by 2 WorldCat member libraries worldwide
Mit Büchse, Schweisshund und Skizzenblock by Manfred Fahle ( Book )
1 edition published in 2003 in German and held by 2 WorldCat member libraries worldwide
Long-term learning in vernier acuity : effects of stimulus orientation, range and of feedback /Manfred Fahle, Shimon Edelman by Manfred Fahle ( Book )
1 edition published in 1993 in Undetermined and held by 1 WorldCat member library worldwide
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Audience level: 0.41 (from 0.35 for Perceptual ... to 0.92 for Disparity ...)
English (40)
German (8)