SENSATION AND PERCEPTION.
Distinguish between sensation and perception
Psychophysics: absolute threshold and difference threshold
Identify each major sensory system, their receptors, and
type of sensory information each receives
Perception: selection, organization and interpretation
SENSATION
A process by which our sensory receptors and nervous system
receive and represent stimulus energy
Process of receiving, converting, and transmitting
information from the outside world
(input of
sensory information)
Perceptual Features: Basic stimulus patterns
Sensory Coding: Converting important features of the
world into neural messages understood by the brain
Sensory Localization: Type of sensations you
experience depends on which area of the brain is activated
SENSORY SYSTEM.
• Vision
• Hearing
• Smell
(olfaction)
• Taste
(gustation)
• Vestibular
sense (balance)
• Kinethesis
(body movement)
• Touch
(pressure, pain, temperature)
VISION
• Visual
receptor cells located on retina: rods for night vision and cones for color
vision
• The
eye captures light and focuses it on the visual receptors, which convert light
energy to neural impulses sent to the brain
HEARING
• Audition
(hearing) occurs via sound waves, which result from rapid changes in air
pressure caused by vibrating objects
• Receptors
located in the inner ear (cochlea) tiny hair cells that convert sound energy to
neural impulses sent along to brain
SMELL AND TASTE
Olfaction (smell) receptors are located at top of nasal
cavity
Gustation - (taste) receptors are taste buds on tongue. Four basic tastes: sweet, salty, sour and
bitter
TOUCH/PRESSURE
• Vestibular
sense (sense of balance) results from receptors in inner ear
• Kinethesis
- (body posture, orientation, and body movement) results from receptors in
muscles, joint and tendons
• Skin
senses detect touch (pressure, temperature and pain)
PROCESSING
Sensory reduction - filtering and analyzing of
sensations before messages are sent to the brain
Transduction - process of converting receptor energy into
neural impulses the brain can understand
Adaptation - decreased sensory response to continuous
stimuli
PSYCHOPHYSICS
• Study
of the relationship between the physical properties of stimuli and a person’s
experience of them
• Absolute
threshold - minimum amount of energy we can detect
• Difference
threshold - (jnd) the smallest change in a stimulus we can detect
CONCEPTS DEFINED
Our sensory and
perceptual processes work together to help us sort out complex processes
SENSATION
Bottom-Up Processing
- Analysis
that begins with the sense receptors and works up to the brain’s
integration of sensory information
Top-Down Processing
- Information
processing guided by higher-level mental processes
- As
when we construct perceptions drawing on our experience and expectations
- Absolute
Threshold
- minimum
stimulation needed to detect a particular stimulus 50% of the time
- Difference
Threshold
- minimum
difference between two stimuli required for detection 50% of the time
- just
noticeable difference (JND)
- Signal
Detection Theory
- predicts
how and when we detect the presence of a faint stimulus (signal) amid
background stimulation (noise)
- assumes
that there is no single absolute threshold
- detection
depends partly on person’s
- experience
- expectations
- motivation
- level
of fatigue
SIGNAL DETECTION THEORY
- predicts
how and when we detect the presence of a faint stimulus (signal) amid
background stimulation (noise)
- assumes
that there is no single absolute threshold
Detection depends partly on person’s
- experience
- expectations
- motivation
- level
of fatigue
SUMMARY
Stimuli and Receptors create experience which may be used to
sense the external world.
Sensation is experience based
PERCEPTION.
a process of
organizing and interpreting sensory information, enabling us to recognize
meaningful objects and events.
“…a constructive process by
which we go beyond the stimuli that are presented to us and attempt to
construct a meaningful situation”.
It is our reaction
to the incoming stimulus
PERCEPTION PROCESSING
Prior
experience leads you to expect to see certian things.
Certian is
misspelled but you filled in the gap!
• Top-down: perception is guided by higher-level knowledge, experience,
expectations, and motivations
• Bottom-up:
perception that consists of recognizing and processing information about the
individual components of the stimuli
Key
Concepts:
- Selection
- Organization
- Interpretation
- Subliminal
perception and ESP
Selection
Affected
by:
• Selective
attention (novelty, familiarity,
• Feature
detectors (brain)
• Habituation
(getting used to)
ORGANIZATION OF STIMULI
Organization
Our minds
likes simplicity/shortcuts to understand
the world
• Figure-Ground
Organization: Inborn part of a stimulus stands out as a figure (object) against
a less prominent background (ground)
Gestalt Principle
• Rules
that summarize how we tend to organize bits and pieces of information into meaningful
wholes
Organization
is affected by:
• Figure
ground (separation of background)
• Nearness:
Stimuli that are near each other tend to be grouped together
• Similarity:
Stimuli that are similar in size, shape, color, or form tend to be grouped
together
• Closure/proximity:
Tendency to complete a figure so that it has a consistent overall form
• Contiguity:
Nearness in time and space; perception that one thing has caused another
• Common
Region: Stimuli that are found within a
common area tend to be seen as a group
Constancy
influences the organization of stimuli:
• Size
constancy
• Shape
constancy
• Color
constancy
• Brightness
constancy
INTERPRETATION
Four
factors are important for interpretation:
• Perceptual
adaptation
• Perceptual
set
• Individual
motivation
• Frame
of reference
• Brightness
constancy
Subliminal
interpretation:
• Stimuli
that occur below the threshold of our conscious awareness but have a weak, if
any effect on behavior
Depth Perception
Ability to see three-dimensional space and to accurately
judge distances
What do you need to perceive distance and depth?
• Depth
Cues: Features of environment, and messages, that supply information about
distance and space
• Binocular
Depth Cue: Depth cue that can be sensed with two eyes
Height Perception
• Context
is important in judging the height!
• The
mind decides the height of the object by comparing the object with features of
the environment
Distance Perception.
Cues for depth:
– Linear
Perspective: Based on apparent convergence of parallel lines in environment
– Overlap
(Interposition): When one object partially blocks another
– Texture
Gradients: Texture changes can contribute to depth perception; coarse texture
implies closeness, fine texture implies distance
– Relative
Motion (Motion Parallax): Nearby objects move a lot as your head moves; distant
objects move slightly
Perception of Motion
• How
do you know that you are moving (forward or backwards)?
• How
do you approximate the speed?
• Background
is important (the concept of figure/background applies)
Illusion
Misleading or
distorted perceptions of stimuli that actually exists (error in perception)
Hallucination: When
people perceive objects or events that have no external basis in reality
PERCEPTION EXPECTANCIES
• Bottom-Up
Processing: Analyzing information starting at the bottom (small units) and
going upward to form a complete perception
• Top-Down
Processing: Preexisting knowledge that is used to rapidly organize features
into a meaningful whole
• Perceptual
Set: Readiness to perceive in a particular manner, induced by small
expectations
0 Comments