Biomaterial Database

Coherent motion perception fails at low contrast. 2005

Louise S Delicato, and Andrew M Derrington

School of Biology (Psychology), Henry Wellcome Building, University of Newcastle upon Tyne, Newcastle upon Tyne, England NE2 4HH, UK. l.s.delicato@ncl.ac.uk

If the Fourier components of a moving plaid have similar temporal frequency, spatial frequency and contrast, coherent motion is perceived according to subjective judgements. We have devised a more objective method of determining the conditions required for coherent motion. Moving plaid stimuli were created with one stationary component. Plaids with a stationary component always have a single perceived direction of motion, which is determined by the presence or absence of coherent motion. In a temporal two-interval forced-choice paradigm we used a direction discrimination task to investigate the effect of varying the temporal and spatial characteristics of the Fourier components and pattern contrast on the probability of coherent motion perception. Agreement across observers regarding the conditions required for coherent motion was excellent using this more objective method. We find that patterns do not produce coherent motion when presented at contrast threshold, irrespective of how similar the Fourier components are. We also confirm that when the temporal frequency, spatial frequency and contrast of the gratings are sufficiently similar, observers report the direction of motion indicating coherent motion.

UI	MeSH Term	Description	Entries
D007600	Judgment	The process of discovering or asserting an objective or intrinsic relation between two objects or concepts; a faculty or power that enables a person to make judgments; the process of bringing to light and asserting the implicit meaning of a concept; a critical evaluation of a person or situation.	Judgement,Judgements,Judgments
D008960	Models, Psychological	Theoretical representations that simulate psychological processes and/or social processes. These include the use of mathematical equations, computers, and other electronic equipment.	Model, Mental,Model, Psychological,Models, Mental,Models, Psychologic,Psychological Models,Mental Model,Mental Models,Model, Psychologic,Psychologic Model,Psychologic Models,Psychological Model
D009039	Motion Perception	The real or apparent movement of objects through the visual field.	Movement Perception,Perception, Motion,Perception, Movement
D010364	Pattern Recognition, Visual	Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.	Recognition, Visual Pattern,Visual Pattern Recognition
D010775	Photic Stimulation	Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.	Stimulation, Photic,Visual Stimulation,Photic Stimulations,Stimulation, Visual,Stimulations, Photic,Stimulations, Visual,Visual Stimulations
D011594	Psychometrics	Assessment of psychological variables by the application of mathematical procedures.	Psychometric
D004192	Discrimination, Psychological	Differential response to different stimuli.	Discrimination, Psychology,Psychological Discrimination
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012684	Sensory Thresholds	The minimum amount of stimulus energy necessary to elicit a sensory response.	Sensory Threshold,Threshold, Sensory,Thresholds, Sensory
D013028	Space Perception	The awareness of the spatial properties of objects; includes physical space.	Perception, Space,Perceptions, Space,Space Perceptions