problem 4 - object recognition

Question 1

apparent movement

Answer 1

when two stimuli that are in slightly different positions are flashed one after the other, movement is perceived - there is actually no movement but it looks like there is

Question 2

illusory contours

Answer 2

finishing a figure in your head without lines being there

Question 3

law of pragnanz

gestalt laws of perceptual organization

Answer 3

every stimulus pattern is seen in such a way that the resulting structure is as simple as possible

Question 4

law of similarity

gestalt laws of perceptual organization

Answer 4

similar things appear to be grouped together

Grouping can also occur because of similarity of shape, size or orientation

Question 5

law of good continuation

gestalt laws of perceptual organization

Answer 5

points that, when connected, result in straight or smoothly curving lines are seen as belonging together + the lines are seen in a way that follows the smoothest path

Question 6

law of proximity/nearness

gestalt laws of perceptual organization

Answer 6

things that are near each other appear to be grouped together

1. Principle of common region: elements that are within the same region of space appear to be grouped together
2. Principle of uniform connectedness: a connected region of visual properties, such as lightness, color, texture, or motion, is perceived as a single unit
3. Principle of synchrony: visual events that occur at the same time are perceived as belonging together

Question 7

law of common fate

gestalt laws of perceptual organization

Answer 7

things that are moving in the same direction appear to be grouped together

Question 8

law of meaningfulness or familiarity

gestalt laws of perceptual organization

Answer 8

things that form patterns that are familiar or meaningful are likely to become grouped together

Question 9

figure-ground segregration

Answer 9

separate objects (figures) stand out from their background (ground) e.g. lamp (figure) on wall (ground)

Question 10

properties of figure & ground

Answer 10

• The figure is more ‘thinglike’ & more memorable that the ground
• The figure is seen as being in front of the ground
• The ground is seen as unformed material & seems to extend behind the figure
• Border ownership: the contour separating the figure from the ground appears to belong to the figure = the border is associated with the figure

Question 11

recogntion by components theory (Biederman)

main idea

Answer 11

our recognition of objects is based on features called geons
* these geons are basic units of objects
* if we can perceive an object’s geons, we can identify the object
* proposed 36 diff geons

Question 12

Non-accidental properties (NAPs)

Answer 12

properties of edges in the retinal image that correspond to the properties of edges in the 3D environment

E.g. an actual coin will appear curved from almost any viewpoint - the property of curvature is called a NAP because the only time it doesn’t occur is when you view the quarter edge-on
* Because this edge-on viewpoint occurs only rarely, it is called an accidental viewpoint

Question 13

criteria for geons

Answer 13

• discriminability: each geon has a unique set of NAPs (e.g. 3 parallel straight lines for a rectangular geon)
• viewpoint variance: NAPs are visible from most viewpoints
• componential recovery: the ability to identify an object if we can identify its geons

Question 14

feature integration theory

Answer 14

Spatial attention must be directed to relevant stimuli in order to integrate the features into the perceived object, must be deployed sequentially for each item in array

visual object perception occurs in two ways:
1. Pre-attentive stage: object is broken down into features → rapid & unconscious
2. Focused attention stage: features are recombined into whole object → conscious attention

Question 15

visual search experiment

feature integration theory

Answer 15

pop-out search task (feature search condition): detect green dot between many red squares. (the number of stimuli is irrelevant) - preattentive

conjunction condition: detect green dots between many green and red squares and circles (both features have distracting stimulus) - focused attention

Question 16

agnosia

Answer 16

cannot identify items only through vision, but can identify them through other sensory processes (e.g. touch, smell, etc.)

no loss of general knowledge + no loss of vision (because features such as color can still be described)

Problem with analytical processing

Question 17

apperceptive agnosia

Answer 17

only has problems when little feature information is available (everything else works well in this version)
* Object constancy is compromised (ability to overcome the slight variability of feature information when object is viewed under different circumstances) - caused by lesion in the right hemisphere

Question 18

integrative agnosia

Answer 18

inability to integrate features into parts & parts into a whole
* can identify separate parts/features, but then fail to see them coherently
* Becomes problematic if some parts of overall object are covered
* Damage in posterior/ventral area

Question 19

associative agnosia

Answer 19

can perceive an object with the visual system, but isn’t able to assign meaning to it
* fails to create pairs of functionally similar objects because they dont know their functions
* caused by damage to the left posterior temporal cortex

Question 20

prosopagnosia

Answer 20

inability to recognize a person just based on vision (BUT they can identify that person when hearing the voice)
* Unrelated to any intellectual deficits→ caused by damage to FFA-area (Fusiform Face Area)
* Problem with holistic processing

Question 21

alexia

Answer 21

characterized by reading problems that occur after a patient has a stroke or head trauma

although they understand spoken speech and can speak normally, reading is pains­takingly difficult