Cognitive Psychology Chapter III Perception (103-110) Flashcards
What is the key claim of template theories?
That we have stored a loooooooot of templates in our minds. When we perceive patterns, we choose a template that exactely fits what we observe.
What are “templates”?
“Templates” are highly detailed models of patterns, we might recognize.
Template theory + chess players + authors:
Chess players who have saved a lot of patterns from previous games use a matching mechanism in line with template theories to recall previous games. (Gobet, Jackson 2002)
Example for a problem with template theories:
Already Hoffding (1891) noted that one can recognize a letter, despite variations in size, form, style etc. and should we really have stored a template of each possibility? Think security feature of websites with pictures of wobbly letters: Humans can recognize them, machines not so well.
As templates are considered to be too restricted, they were soon replaced by.. ( + Researchers)
.. prototypes! (e.g. Franks and Bransford, 1971)
What is a prototype?
a prototype is an average of a class of related objects/patterns
What is exiting about prototypes? + research(er)
We seem to form them as an integration of the most typical features of a pattern, without ever having seen an instance that exactly matches the prototype. (Posner and Keele, 1968 -> subj.s recognized prototypes as familiar, but have only been shown distorted instanzes (e.g. dots forming a triangle)
Yet another branch of theories besides template and prototype theories in pattern recognition?
feature(-matching) theories
By whom and what kind of demons does the Pandemonium Model consist of?
Oliver Selfridge’s pandemonium model, consists of: image demon, feature demons, cognitive demons, decision demon
Study, name, effects?
H H S S H H S S H H H S S S H H S S H H S S
Part.s had to identify stimuli either at local or global level (Navon, 1977).
When local features are close together there is a global precedence effect (-> global recognition not slowed down by incongruence, but local).
When letters are more widely spaced a local precedence effect:
S S
S S S
S S
Evidence for feature-matching theories comes from neurological and physiological research. Who and examples:
Hubel and Wiesel: single-cell recordings show evidence for orientation sensitive cells in V1.
DeValois and DeValois: cells sensitive to corners and angles
More complex/accurate picture of feature-recognition in the brain:
many cells serve multiple purposes,
information gathering about different features happens in parallel,
e.g. two streams: the “what” (= color shape identity) and the “where” (=location and motion) stream
Structural-Description Theory:
Name and specific theory!
Irving Biederman’s recognition-by-components (RBC) theory.
What is the recognition by components theory?
According to Biederman, we quickly recognize objects by observing the edges of them and then decomposing the object into geons.
Prosopagnosia?
The inability to recognize faces
What is a geon?
Geons can be used to build up many basic shapes and then many many basic objects. They are simple and viewpoint invariant.
Biederman’s theory is an example of a…
… feature-matching theory.
The dorsal pathway is also called the …
… “where” pathway.
The “what” pathway is also called the …
… ventral and is responsible for color, shape and identity.
One example of a feature matching model:
The Pandemonium Model
What happens “in the pandemonium”?
Metaphorical demons with specific duties receive and analyze the features of a stimulus.
Image deamon -> feature demon -> cognitive demon (shout when they receive certain combinations of features) -> decision demon (listens to who shouts loudest)
According to constructivits percepts are based on 3 things:
- what we sense
- what we know
- what we can infer
Two examples for feature-matching approaches to perdepction:
- Selfridge’s Pandemonium Model
- Biederman’s RBC Theory
One kind of effect that speaks in favor for constructive approaches to perception:
context effects
An example for a context effect and a description:
configural-superiority effect
Objects presented in certain configurations are easier to recognize than in isolation altough the configurations are more complex.
A smilar effect to the configural-superiority effect known from linguistics:
word-superiority effect (letters in words are easier to identify than in isolation)
Deficit associated with damage to the “how” pathway:
optic ataxia, e.g. deficit in reaching for stuff
The only “true” form of color blindness?
rod monochromacy / achromacy
What’s the name for color blindness, where only one mechanism is not functioning correctly?
dichromacy
Examples for dichromacy:
- red-green color blindness
