Chapter 3-Perception Pt. 2 Flashcards
Helmholtz’s Theory of Unconscious Inference
- 1860s
- top down theory
- some of our perceptions are the result of unconscious assumptions we make about the enviro
- we use our knowledge to inform our perceptions
- we infer much of what we know about the world
Likelihood principle
- Helmholtz’s
- we perceive the world based in the way that is “most likely” based on our past experiences
Perceptual organization
“old” view: structuralism
-perception involves adding up sensations
“New” view: Gestalt psychologists
-the mind groups patterns according to laws of perceptual organization
Coglab: Apparent motion
- short ISI (the interstimulus interval) resulted in the two dots being presented simultaneously
- long ISI resulted in the two dots being presented alternatively
- intermediate ISI resulted in the perception of motion
The best ISI increases with
Distance
For larger separations the stimulus must ________
“Move” a farther distance, which presumably requires a greater length of time
Theoretical importance of apparent motion
- perception involves a process of perceptual organization that requires an understanding of the relationship between the stimuli
- if perception involves simply detecting the properties of the physical world, one would expect that the observer either be able to detect the stimuli or not, but the perception is quite different: motion is observed, even though it is not a property of either of the stimuli
Gestalt Laws of Perceptual Organization
- law of good continuation: lines tend to be seen following the smoothest path
- law of pragnanz: simplicity or good figure
- law of similarity: similar things appear grouped together
- law of proximity: things near each other appear grouped together
- law of common fate: things moving in the same direction appear to be grouped together
Gestalt laws often provide ______
Accurate information about properties of the environment
- reflect experience
- experience is important but does not overcome perceptual principles
Gestalt laws are intrinsic
physical regularities
Oblique effect
-people can perceive verticals and horizontals more easily than other orientations
Light from above assumption
- light comes from above
- is usually the case in the environment
- we perceive shadows as specific information about depth and distance
Semantic Regularities
semantic regularities are the characteristics associated with the functions carried out in different types of scenes
A scene scheme is the knowledge of what a given scene ordinarily contains (what you expect)
Semantic regularities example
The gym-review results
Palmer (1975)-review results
Bayesian interference
-Thomas Bayes
Ones estimate of the probability of a given outcome is influenced by two factors:
- The prior probability (our initial belief about the probability of an outcome, hypothesis)
- The likelihood of an observation given the outcome (hypothesis)
Bayesian inference equation
P(AB)=P(A)P(B|A)=P(B)P(A|B)
P(hypothesis|observation)P(observation)= P(hypothesis)P(observation|hypothesis)
So P(hypothesis|observation) is proportional to P(hypothesis)*P(observation|hypothesis)
Review charts in notes
Neurons and the Environment
Neurons become tuned to respond best to what we commonly experience
- horizontals and verticals
- experience dependent plasticity
Neurons and the Environment example
Greeble
Movement facilitates _______
Perception
Movement helps us perceive things in our environment more accurately than static, still images
E.g. horse
The interaction of perception and action
Our actions within or upon the environment around us involve a constant stream of updating perceptions and recognition of very subtle changes
What stream
Identifying an object
Temporal lobe (ventral pathway)
Perception area
Where steam
Identifying the objects location
Parietal lobe (dorsal pathway)
Action area
Single dissociation
One function is lost, another remains
Example monkey A has damage to temporal lobe. The monkey is no longer able to identify objects (what) but can still identify locations(where)
Do what and where rely on different mechanisms (for single dissociation)
Yes although they may not operate totally independent of one another
Double dissociation
Required two individuals with different damage and opposite deficits
Example: monkey A with temporal lobe damage has intact where but impaired what; Monkey B with parietal lobe damage has intact what but impaired where
Therefore what and where streams must have different mechanisms AND operate independently of one another
DF
Damage to temporal lobe (perception area)
If asked to match orientation of paper to mailbox she could not do it very well
If asked to put letter into mailbox she could do it pretty accurately
Has to do with the fact that her “where” or action area wasn’t damaged
