An inherent property of objects in the world is that they only exist as meaningful entities over certain ranges of scale. If one aims at describing the structure of unknown real-world signals, then ...

/pdf/scale-space-theory-a-basic-tool-for-analysing-structures-at-5umoin3tlu.pdf

Scale-Space Theory : A Basic Tool for Analysing Structures at Different Scales

These experiments use functional magnetic resonance imaging (fMRI) to reveal neural activity uniquely associated with perception of biological motion. We isolated brain areas activated during the viewing of point-light figures, then compared those areas to regions known to be involved in coherent-motion perception and kinetic-boundary perception. Coherent motion activated a region matching previous reports of human MT/MST complex located on the temporo-parieto-occipital junction. Kinetic boundaries activated a region posterior and adjacent to human MT previously identified as the kinetic-occipital (KO) region or the lateral-occipital (LO) complex. The pattern of activation during viewing of biological motion was located within a small region on the ventral bank of the occipital extent of the superior-temporal sulcus (STS). This region is located lateral and anterior to human MT/MST, and anterior to KO. Among our observers, we localized this region more frequently in the right hemisphere than in the left. This was true regardless of whether the point-light figures were presented in the right or left hemifield. A small region in the medial cerebellum was also active when observers viewed biological-motion sequences. Consistent with earlier neuroimaging and single-unit studies, this pattern of results points to the existence of neural mechanisms specialized for analysis of the kinematics defining biological motion.

/pdf/brain-areas-involved-in-perception-of-biological-motion-1h8vne119v.pdf

Brain Areas Involved in Perception of Biological Motion

Fundamental to spatial knowledge in all species are the representations underlying object recognition, object search, and navigation through space. But what sets humans apart from other species is our ability to express spatial experience through language. This target article explores the language of objects and places, asking what geometric properties are preserved in the representations underlying object nouns and spatial prepositions in English. Evidence from these two aspects of language suggests there are significant differences in the geometric richness with which objects and places are encoded. When an object is named (i.e., with count nouns), detailed geometric properties – principally the object's shape (axes, solid and hollow volumes, surfaces, and parts) – are represented. In contrast, when an object plays the role of either “figure” (located object) or “ground” (reference object) in a locational expression, only very coarse geometric object properties are represented, primarily the main axes. In addition, the spatial functions encoded by spatial prepositions tend to be nonmetric and relatively coarse, for example, “containment,” “contact,” “relative distance,” and “relative direction.” These properties are representative of other languages as well. The striking differences in the way language encodes objects versus places lead us to suggest two explanations: First, there is a tendency for languages to level out geometric detail from both object and place representations. Second, a nonlinguistic disparity between the representations of “what” and “where” underlies how language represents objects and places. The language of objects and places converges with and enriches our understanding of corresponding spatial representations.

“What” and “where” in spatial language and spatial cognition

Vol. 1 1. Neural Basis of Vision. 2. Color Vision. 3. Depth Perception. 4. Perception of Visual Motion. 5. Perceptual Organization in Vision. 6. Attention. 7. Visual Object Recognition. 8. Motor Control. 9. Neural Basis of Audition. 10. Auditory Perception and Cognition. 11. Music Perception and Cognition. 12. Speech Perception. 13. Neural Basis of Haptic Perception. 14. Touch and Haptics. 15. Perception of Pain and Temperature. 16. Taste. 17. Olfaction. Vol. 2 1. Kinds of Memory. 2. Models of Memory. 3. Cognitive Neuroscience. 4. Spatial Cognition. 5. Knowledge Representation. 6. Psycholinguistics. 7. Language Processing. 8. Problem Solving. 9. Reasoning. 10. Decision Making. 11. Concepts & Categorization. 12. Cognitive Development. 13. Culture & Cognition. Vol. 3 1. Associative Structures in Pavlovian and Instrumental Conditioning. 2. Learning: Laws and Models of Basic Conditioning. 3. Reinforcement Learning. 4. Neural Analysis of Learning in Simple Systems. 5. Learning Mutants. 6. Learning Instincts. 7. Perceptual Learning. 8. Spatial Learning. 9. Temporal Learning. 10. Role of Learning in Cognitive Development. 11. Language Acquisition. 12. Role of Learning in the Operation of Motivational Systems. 13. Emotional Plasticity. 14. Anatomy of Motivation. 15. Hunger Energy Homeostasis. 16. Thirst and Water-Salt Appetite. 17. Reproductive Motivation. 18. Social Behavior. 19. Addiction. Vol. 4 1. Representational Measurement Theory. 2. Signal Detection Theory. 3. Psychophysical Scaling. 4. Cognitive Neuropsychology. 5. Functional Brain Imaging. 6. Neural Network Modeling. 7. Parallel and Serial Processing. 8. Methodology and Statistics in Single-Subject Experiments. 9. Analysis, Interpretation, and Visual Presentation of Experimental Data. 10. Meta-Analysis. 11. Mathematical Modeling. 12. Analysis of Response Time Distributions. 13. Testing and Measurement. 14. Personality and Individual Differences. 15. Electrophysiology of Attention. 16. Single vs. Multiple Systems of Memory and Learning. 17. Infant Cognition. 18. Aging and Cognition.

Stevens' handbook of experimental psychology

The yield of alkenols and cycloalkenols is substantially improved by carrying out the reaction of olefins with formaldehyde in the presence of selected catalysts. In accordance with one embodiment, alk-3-en-1-ols are produced in good yields from isobutylene and formaldehyde in the presence of organic carboxylic acid salts of Group IB metals.

The Organization of the Cochlear Receptor

The distribution of human motion detector properties in the monocular visual field.

We studied the detection of coherent motion in stroboscopically moving random-dot patterns for foveal vision and at eccentricities of 6, 12, 24, and 48 deg in the temporal visual field. Threshold signal-to-noise ratios (SNR’s) were determined as a function of velocity for a range of stimulus sizes. It was found that the motion-detection performance is roughly invariant throughout the temporal visual field, provided that the stimuli are scaled according to the cortical magnification factor to obtain equivalent cortical sizes and velocities at all eccentricities. The maximum field velocity compatible with the percept of coherent motion increased about linearly with the width of the square stimuli. At this high-velocity threshold any pixel crossed the field in five to nine equal steps with a constant total crossing time of 50–90 msec, regardless of stimulus size or eccentricity. The lowest SNR values were reached at the optimal or tuning velocity V0. They approached the amazingly low values of 0.04–0.05 for large stimuli and at all eccentricities. Regardless of stimulus size, the parameter V0 increased about linearly with eccentricity from roughly 1 deg sec−1 at the fovea to some 8 deg sec−1 at 48 deg in the temporal visual field.

Detection of coherent movement in peripherally viewed random-dot patterns.

Limits in perception

We report a visual motion aftereffect (MAE) that reveals simultaneous adaptation in independent motion channels coding for 'slow' or for 'fast' velocities. Dynamic random noise test patterns with low refresh frequencies or static test patterns can be used to test for MAEs mediated by slow channel adaptation, whereas MAEs produced by fast channel adaptation may be detected with noise patterns refreshed at high rates. After adaptation to transparent motion containing both a slow and a fast component, test patterns containing both high and low refresh frequencies produce a transparent, two-component MAE, revealing two distinct channels.

/pdf/a-new-transparent-motion-aftereffect-3fj0t5m8we.pdf

W.A. van de Grind

Papers

The distribution of human motion detector properties in the monocular visual field.

Detection of coherent movement in peripherally viewed random-dot patterns.

Limits in perception

A New transparent motion aftereffect

Inhomogeneity and anisotropies for motion detection in the monocular visual field of human observers.