Chapter Three - Perception Flashcards
What is perception?
-experience resulting from stimulation of the senses
What are 3 basic concepts of perceptions?
- perceptions can change based on added info
- involves a process similar to reasoning/problem solving
- occur in conjunction with actions
Is human perception unique to humans?
- possibly, yes
- AI has failed to match level of perception
What is the inverse projection problem?
- task of determining object responsible for a particular image on retina
- involves starting with retinal image
- then extending outward to source of that image
Why is perception so difficult for a machine? (2)
- objects can be hidden or blurred
2. objects look different from different viewpoints (viewpoint invariance)
what is bottom-up processing?
- start at bottom of system
- environmental energy stimulates receptor
what is top-down processing?
- originates in brain
- top of perceptual system
- previous knowledge affects perception
What are direct perception theories?
- bottom-up processing
- perception starts with the senses
- parts are put together
What are constructive perception theories?
- top-down processing
- people actively construct perceptions using info based on expectations
What is an example of how top-down processing is involved in perception of objects?
-blurred blobs are identical but perceived as different objects due to orientation + context
What is speech segmentation?
-ability to tell when one word ends and another begins
How is top-down processing involved in speech?
- hearing words in a sentence in a foreign language
- ability to pick out certain words based on context
What is the direct pathway model of pain?
- early model, emphasized sensory receptors that send pain messages directly to the brain
- bottom-up processing model
What pain phenomenon challenges bottom-up processing of pain?
the placebo effect
What is Helmholtz’s Theory of Unconscious Inference?
- top-down theory
- some perceptions are result of unconscious assumptions we make about environment
- most of what we know about the world is an inference
What is the likelihood principle?
-perceive the world in way that is “most likely” based on our past experiences
What is the “Old” view of perceptual organization?
- structuralism
- perception involves adding up sensations
What is the new view of perceptual organization?
Gestalt psychologists
What do Gestalt psychologists believe?
-mind groups patterns according to laws of perceptual organization
What is apparent movement?
- movement is perceived even though nothing is moving
- whole is different than sum of its parts
What are the 3 Gestalt Laws of Perceptual Organization?
- Law of good continuation
- Law of pragnanz (simplicity/good figure)
- Law of similarity
What is the law of good continuation?
-lines tend to be seen as following the smoothest path
What is the law of pragnanz?
-every stimulus pattern is seen so resulting structure is as simple as possible
What is the law of similarity?
-similar things appear grouped together
Gestalt laws often provide accurate information about properties of _________
the environment
Where do the Gestalt Laws come from?
- intrinsic
- role of experience is minor
What do modern perceptual psychologists believe?
-perception is influenced by knowledge of regularities in environment (agreement with Helmholtz)
What are physical regularities?
regularly occurring physical properties
What are semantic regularities?
-characteristics associated with the functions carried out in different types of scenes
What is the oblique effect?
-people can perceive verticals + horizontals more easily than other orientations
What is the light-from-above assumption?
- light comes from above
- perceive shadows to inform us about depth + distance
What is a scene schema?
-knowledge of what a given scene ordinarily contains
EX: professor’s office
What is perception according to the inferential approach?
- given an image (input) + the knowledge about regularities of physical world
- pick most probably interpretation of image
What is Bayesian Inference?
- one’s estimate of the probability of a given outcome is influenced by 2 factors:
1. prior probability
2. likelihood of a given outcome
What are the 4 approaches to perception?
- Helmholtz’s unconscious inference
- Gestalt Laws of organization
- Regularities in the environment
- Bayesian inference
Which of the 4 approaches to perception are bottom-up? Top-down?
Bottom-Up:
Gestalt Laws of Organization
Top-Down:
Helmholtz’s unconscious inference
regularities in environment
Bayesian inference
What do modern psychologists claim about the Gestalt Laws?
laws could have also been created by experience
What happens to neurons over time?
-become tuned to respond best to what we commonly experience
Why is it beneficial that neurons be atuned to stimuli over time?
- natural selection
- neurons can be trained to respond to specific stimuli
What is experience-dependent plasticity?
mechanism through which the structure of the brain is changed by experience
How did Blakemore and Graham Cooper demonstrate plasticity?
- raised kittens in space in which they only saw vertical black + white stripes on walls
- visual cortex had been reshaped
experience-dependent plasticity plays a role in activation of the _________
fusiform face area (FFA)
What happened after “Greeble recognition?”
-FFA fired as much for Greebles as it did for faces
_____ helps us perceive things in our environment more accurately than static images
movement
What are the 2 processing streams?
- what stream: identifying an object
- where stream: identifying object’s location
What two methods were used to discern the two processing streams?
- brain ablation
2. neuropsychology
How did Ungerleider and Mishkin study about the what and where pathway?
-studied how removing part of a monkey’s brain affected its ability to identify an object + determine its location
What is object discrimination?
- monkey shown object
- must pick correct object
What is landmark discrimination?
- cylinder indicates which side monkey’s food is on
- location
The temporal lobe controls which pathway?
where/dorsal
The occipital lobe controls which pathway?
what/ventral
What did Milner and Goodale find?
- studied 34 year old woman with damage to temporal lobe
- asked to rotate card
- asked to mail a card
Is the psychological repertoire universal?
no
