Chapter 3-Perception Flashcards
Perception is
Experience resulting from stimulation of the senses
Basic concepts of perception
- Perceptions can change based on added information
- Involves a process similar to reasoning or problem solving
- Perceptions occur in conjunction with actions
Is it possible that true human perceptual process are unique to humans?
Yes-attempts to create artificial forms of perception have been met with limited success
Problems with designing a perceiving machine
Inverse Projection Problem
- involves determining the object responsible for a particular image on the retina
- involves extending outward from retinal image to the source of that image
Objects can be hidden or blurred
Objects look different from different viewpoints
-object invariance
Direct perception theories
-Bottom up processing
Perception comes from stimuli in the environment, parts are identified and put together, and then the recognition occurs
Constructive perception theories
-top down processing
People actively construct perceptions using information based on expectation
Bottom up processing
- Perception may start with the senses
- incoming raw data
- energy registered on receptors
Top down processing
- perception may start in the brain
- person’s knowledge, experience, expectations
Top down processing examples
“Blob experiment” confirms perception is not only based on inputs
Speech segmentation
Experiencing pain
Can be be bottom up process (early model that emphasized nociceptors that sent pain messages directly to brain)
Can be top down model because of expectations, attention, distraction can affect how we experience pain (Placebo effect, play games during bandage change)
Bottoms up processing: behavioural
Recognition by components theory (RBC)
- we perceive objects by perceiving elementary features
- Geons: three dimensional volumes
- objects are recognized when enough information is available to identify objects geons’s
Geons are _______
Innate
Specific objects and their spatial relations are not
The more Geons the more ________ we are to recognize the object
Confident
Geons
Discriminability: Geons can be distinguished from other Geons from almost all viewpoints
Resistance to visual noise: Geons can be perceived in “noisy” conditions
Distinct: 36 different geons have been identified
Visual search
- Triesman
- visual perception and visual attention
Identification of objects involve two stages:
- A preattentive stage that automatically identifies basic features
- An attentive stage that combines the basic features to form objects
Identification of objects also depends on what else is visible
Visual search can be used for two basic purposes:
To identify the basic features of visual perception that are identified preattentively
To investigate the nature of the attentive stage
Visual search is a
Bottom up process
Preattentive stage
If search time is independent of the number of distractors (1 dimensional)
Attentive stage
If search time increases with the number of distractors
Exogenous cue
A unique value that draws attention
Search slope=0 (pops out)
Number of distractors is insignificant if there is only one feature
Serial process
- need to combine properties to detect target
- combination is not automatic
- attention is needed to “weld” properties together
- search is a serial process-time needed depends on number of items
- spotlight travels at about 50ms/item
Feature integration theory (FIT)
For preattentive stage
- automatic
- no effort or attention
- unaware of process
- object analyzed into features
For focused attention stage
- attention plays a key role
- features are combined
Treisman and Schmidt
- participants report combination of features from different stimuli
- illusory conjunctions occur because features are “free floating”
R.M.-Balint’s syndrome
Inability to focus attention on individual objects
High number of illusory conjunctions reported
Feature integration theory (FIT) is
Mostly bottom up processing
Top down processing influences processing when participants are told what they would see
