TOPIC 5 : PERCEPTION Flashcards
WHAT IS ATTENTION
attention is the ability to focus on a stimuli in the environment or conscious processes, while not processing other info.
Selective attention
conscious awareness focus on a particular stimulus
Divided attention
conscious awareness is spread over two or more stimuli
The myth of multitasking
“multitaskers” actually just switch rapidly between tasks.
problems with multitasking
- Decreases productivity and speed
- Decrease creative thinking
- Increases release of stress hormones and stress
Early-selection theory
unimportant information is “filtered out” early on before processing
cocktail party phenomenon
- part of early-selection theory
- when you ignore all other convos around you and pay attention to one person
the problem with cocktail part phenomenon
when someone across the room mentions your name and you notice.
inattention blindness
when visual attention is engaged, other events fail to be perceived
change blindness
when a visual stimulus is interrupted and charged, we cannot detect the charge
What does change blindness suggest?
suggests that the entire visual scene is not fully attended to, encoded, or retained.
Gastalt psychology
- in form perception
- Asked how are sensation organized into perceptions ?
- Motto: the whole is different then the sum of parts
- Figure V.S Ground: what is the object and what is the background?
Laws of perpetual
governed how related stimuli are associated
Pros and Cons of laws of perpetual
PROS:
- Holistic approach: perpetual experience cannot be broken down into concepts
CONS:
- not good for making predictions.
- not good at explanations
Pattern perception
- Template models
- Prototype models
- Feature model
- Structural models
Template models
- input compared to fixed template stored in memory
- stimulus categorized into exact match.
pros and cons for template model
PROS:
- successfully used in machines
CONS:
- cannot handle novel stimuli, or variations in a stimulus.
Prototype models
- input compared to abstract, idealized patterns until best match
- prototype is like an “average” formed by repeated experience
pros and cons to prototype models
PRO:
- more flexible; allows for differences in “goodness” (some category members are more representative than others)
CON:
- how do we perceivespecificthings?; cannot handle context
feature models
- Input broken down into simple component
- features, like line segments
feature list compared to stored catalog
Pros and cons to feature models
PRO:
- can account for variations, and “goodness”
CON:
- features are poorly defined; cannot handle context
structural models
Recognition By components(Biederman, 1987)
- object identified by matching configuration of geons with stored catalog of objects
- evidence: if an object’s geons can be determined, the object can be recognized–even if partially obscured
goons
(geometric icons):
volumetric shapes that can be modified (length, width, etc.), but remain identifiable (cylinder, brick, cone)
pros and cons to structural models
PROS:
- can account for variations
CONS:
- cannot differentiate between two things that have the same geons ; cannot handle context
types of processing
- Bottom-up
- Top-down
Bottom-up
sensory data is gathered, put together, and evaluated on the basis of what emerges from the pattern
Top-down
higher-level processes (e.g., based on context, experience, knowledge) aid in interpreting data gathered by the senses
perceptual set
predisposition to interpret a stimulus in a particular way
perceptual schemas
Mental structures that help us organize the world into a coherent whole.
- Are learned, thus affected by context, culture, & experience
Binocular cues
depth cues requiring two eyes
convergence
feedback from eye muscles provides information on distance to object being focused on
binocular disparity
Each eye sees a slightly different image
- These differences are interpreted in terms of depth
Stereopsis
stereoscopic vision
Monocular(“pictorial”)cues
depth cues applied by one eye
relative size
closer objects cast larger retinal image
linear perspective
parallel lines appear to converge (at “vanishing point”)
relative brightness
dimmer objects seem farther away
elevation
objects closer to the horizon are interpreted as being farther away
texture gradient
texture elements appear smaller and more densely arranged as they get farther away
Motion perception
- structure from motion
- apparent motion
structure from motion
the movement of an object can assist in determining its shape
apparent motion
if two adjacent objects are shown in sufficiently brief succession, one moving object is perceived
Perpetual constancies
- The proximal stimulus is dynamic and changing
- But we perceive the distal stimulus as being constant
- how does this work?
shape constancy
object perceived to have a constant shape, despite changes in shape of retinal image
size constancy
- perceived size of an object doesn’t change, despite variations in size of image on the retina
- depends on knowledge about object’s size, and information about object’s distance
lightness constancy
- perception of greyness of an object’s surface is constant, despite differences in illumination
- depends on knowledge of object’s surface, and information about ambient light
perceptual constancies
- Shape constancy
- size constancy
- lightness constancy
what does perpetual constancies allow?
perceptual constancies allow for an accurate and stable percept of a changing world by applying knowledge in our heads, and information from the world
what can visual illusions tell us?
may tell us how our sensory systems work, and reveal our sensory biases
what is a visual illusion ?
illusions are errors in perception– incorrect interpretations of the world
ponzo illusion
(Ponzo, 1913)
- converging lines give false impression of 3-D depth and distance
- top bar is perceived farther away then bottom bar
Gregory ( 1968, 1990 )
examines Müller-Lyer illusion
- line with arrows at the ends appears shorter then line with wings at the ends.
problem with the Müller-Lyer illusion
illusion is also obtained with circles
conclusions with Müller-Lyer illusions
- stimuli interact with depth perception mechanisms
- false depth perception leads to misapplies size and shape constancy
- you cannot think away an illusion even if you understand how it works
- thus depth perception mechanisms must be “hardwired”
human factors psychology
- applies psychological knowledge to real-world problems
- also known as engineering psychology , cognitive engineering, and ergonomics
Real-world illusion example.
- American Airlines had landing accidents occurring at night in good weather
- Pilots used flight rules not instrumental landings. no mechanical problems
Conrad L. Kraft
suspected pilots experienced a visual illusion approaching city lights while over dark water or land.
what caused the illusions pilots saw ?
black-hole approach illusion
Black-hole approach illusion
when on approach over water on a dark night toward brightly lighted city, pilots misperceive runway to be larger, nearer, and lower in the visual field
ESP (extra sensory perception)
- Telepathy
- Clairvoyance
- Precognition
- Telekinesis or psychokinesis
Telepathy
direct mind-to-mind communication
Clairvoyance
direct perception of distant events
precognition
perception of future events (not guessing!)
tele-/psychokinesis
acting upon objects with the mind
Anecdotes VS Evidence
- Nostradamus (16thcentury)
- Strentz (1986)
Nostradamus (16thcentury)
wrote ambiguous prophesies; only interpretablepost hoc
Strentz (1986)
surveyedNational Enquirer’s psychic predictions
- from 1978-1985, 486 predictions made
- only 2 came true lol.
