Task 5 Flashcards
Mechanisms of middle- and high-level vision (28 cards)
Perceptual Orientation
- grouping
- segregation
- Grouping = process by which visual venents are “put together” into units or objects
- Segregation = process of separating one area or object from another
Gestalt Approach to Percepual Grouping
- structuralism
- apparent movement
- illusory contours
- Structuralism = distinguished between sensations and perceptions
- Apparent movement = principle behind stroboscope; although movement is perceived, nothing is actually moving
- Illusory contours = seeing contours when there are actually none present
Gestalt Principles of Perceptual Organization
- Good Continuation
= point that, when connected, result in straight or smoothly curving lines are seen as belonging together, and the lines tend to be seen in such a way as to follow the smoothest path
- objects that are partially covered by other objects are seen as continuing behind the covering part
Gestalt Principles of Perceptual Organization
- Prägnanz
= every stimulus pattern is seen in such as way that the resulting structure is as simple as possible
Gestalt Principles of Perceptual Organization
- Similarity
= similar things appear to be grouped together
Gestalt Principles of Perceptual Organization
- Proximity
= things that are near each other appear to be grouped together
Gestalt Principles of Perceptual Organization
- Common Fate
= things that are moving into the same direction appear to be grouped together
Gestalt Principles of Perceptual Organization
- Common Region
= elements that are within the same region of space appear to be grouped together
Gestalt Principles of Perceptual Organization
- Uniform Connectedness
= connected region of the same visual properties, such as lightness, color, texture, or motion, is perceived as a single unit
Perceptual Segregation
- in general
= perceptual segregation of one object from another
Perceptual Segregation
- figure and ground
Figure = separate object that stands out from its background; more likely to remeber Ground = background - Figure: - more “thing-like” and memorable - seen as being in front of ground - border ownership - Ground: - seen as unformed material near the borders shared with figure - seems to extend behind figure - lacks shape entirely
Scenes and objects
objects: acted upon; scenes: acted within
Perceiving the gist of a scene
gist of a scene = meaning fo a scene that can be recognized after only a fraction of a second
Global image features
- degree of naturalness = natural scenes: undulating contours; man-made scenes: straight lines
- degree of openness = open scenes: visible horizen and few objects; low degree of openness (=forest): not
- degree of roughness = low roughness scenes (=ocean) few small elements; high roghness scenes (=forest) small and complex elements
- degree of expansion = high: convergence of parallel lines
- color: illustrates property of perception —> past experiences
Regularities in the environment
- physical regularities
= regularly occurring physical properties of the environment
- light-from above assumption = assumtion that light is coming from above
Regularities in the environment
- semantic regularities
= characteristics associated with activities that are common in different types of scenes
Helmholtz’s Theory of Unconscious Inference
= some of our perceptions are the result of unconscious assumptions we make about the environment
- likelihood principle = we perceive the object that is most likely to have caused the pattern of stimuli we have received
Bayesian Inference
= idea that our perception is a combination of current stimulus and our knowledge about conditions of the world — what is and is not likely to occur
- two factors must be considered:
(1) prior probability = likelihood of outcome we are proposing
(2) consistency of hypothesis with each outcome
PPA - Parahippocampal Place Area
- “place area” —> responds to pictures fo buildings, furnished rooms, and empty rooms
- definitely involved in perceiving space
What pathway
- to temporal lobe
- object recognition
Where pathway
- to parietal lobe
- processing information relating to location of objects in space and actions required to interact with them
Perceptual Comittees
- low-level vision
- middle vision
- high-level vision
V1 — low-level vision = cells respond best to lines and edges in specific areas of visual field
V2 — middle-level vision = cells have sensitivity to border ownership and illusory contours
V4 — high-level vision = cells more interested in complex attributes
Naive template theory
= proposal that visual system recognizes objects by matching the neural representation of the image, with a stored representation of the same ‘shape’ in the brain
recognition-by-components model
= Biederman’s model of object recognition; holds that objects are recognized by identities and relationships of their component parts
- based on small unites - Geons = any of the ‘geometric ions’ out of which perceptual objects are built
- like alphabet —> all kinds of combinations
