Karteikarten
four
Karten in diesem Stapel (25)
- 1detection of texture and lines goes back toarea v1 of cortex
- 2what does area v1 of cortex dodetection of texture and lines
- 3area v1 full of cells sensitive toorientation and small line segments
- 4work on orientation and area v1 and lines is byhubel and wiesel 1950s
- 5what did hubel and wiesel 1950s doscreen with object on screen with animal looking at it and recorded action potentials, could tell what those cells were interested in
- 6simple cells:sensitive to orientation, position and size
- 7complex cells:orientation and spatial frequency sensitive, high resting signal, receptive field defined but unstructured, not sensitive to position, prefers thin lines but no off region
- 8hypercomplex cells:(end stopped) like complex but prefers short lines. sensitive to length and can be turned off by stimulus outside its 'classical' receptive field
- 9hubel and wiesel found that simple cells in v1 were what kind of pattern and whystriped regions; on flagged by two off regions or other way around, or one on and off side by side. came in diff sizes and many diff varieties
- 10can test orientation / position / size sensitivity in simple cells byputting small parts of lines of light at different orientations or positions or size over the receptor
- 11the cells get info not from _________ but from ___________not from light
from patterns of activity from the LGN - 12hubel and wiesels LGN idea was thatthe off centre LGN cells would connect to off stripes (simple cells) in V1 and on centre LGN cells to on stripes in V1
- 13hypercomplex cells COULD bemultiple simple cells in a row, which provides it with length sensitivity
- 14texture isspatial detail at a scale which is finer than that which the observer currently defines as the object scale. defined by statistical properties rather than absolute values. if 2 share the same stat props, they are the same. if diff, can be segmented. allows us to see edges of objects defined by changes in surface markings
- 15what was julesz' 1984 texton theorytexton (texture atom) are simplest defining property of texture. textures will segment if differ in terms of texton density. (textons r elongated blobs (lines, shapes) w orientation and length, line endings, line crossings). can be segmented if diff number of textons BUT THIS IS WRONG
- 16nothdurft 1990 said julesz was wrong bc saidsegmentation by line crossing and endings is affected by certain manipulations than segmentation by orientation, random variations disrupt segmentation by crossings and endings and so orientation and size/compact may be the only textons
- 17nothdurft showed in the orientation contrast modelthatits not orientation that is important but local difference in orientation that is important. also showed similar effect for size bc can segment based on local size differences. local differnce that matters rather than averages
- 18orientation opponent orientation contrast cells areorientation sensitive and responds to all texture changes
- 19orientation doubly opponent orientation contrast cells areorientation insensitive, respond to texture changes apart from orientation
- 20two stages of texture processing;extract texture
extract texture boundaries
... also enables discrimination of shadows vs surface changes via similar 2 stage process - 21older adults (and dyslexic and autistic ppl) will struggle with what stage of texture processing2nd; extract texture boundaries
- 22idea that cells are sensitive to orientation change bt central receptive field and surrounding leads to idea of and which leads to whatcentre surround cells for orientation, leading to simultaneous contrast illusion for orientation
- 23orientation version of simultaneous illusion is ____________ where orientation replaces __________tilt-illusion
luminance - 24describe tilt-after effectorientation determined by population of cells sensitive to diff orient. (neural code). prolonged viewing > inhibition. inhibition lasts beyond end of stim, when new orientation is seen the remaining inhib alters neural code and new one is not seen properly so shifted
- 25hypercomplex cells may lead to illusory contours by cells inarea v2
Informationen
- Beschreibung
- PSYCHOLOGY YEAR 2 (1 vision) Karteikarten am four, erstellt von Ki Rai am 23/11/2018.
- Erstellt von
- Ki Rai
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- 5
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