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Chapter 5 Sensation — the window on the world
How does the world out there get in?
Sensation and Perception Sensation: the process by which
stimuli are detected and encoded, enabling us to experience a ping pang as a moving, white object
Perception: the mental process of organizing and interpreting our sensation, enabling us to see not just moving whiteness, but a ping pang.
The Definition Sensation — the process by which
our sensory receptors and nervous system receive and represent stimulus energies from our environment (bottom-up)
Perception — the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
(top-down)
Sensing the World: Some Basic Principles
Sensation depends on specialized cell called sensory receptors which detect stimuli and convert their energy into neural impulses. This process is called sensory transduction—the process by which sensory receptors convert stimuli (physical, chemical energy) into neural impulses.
Thresholds (阈限) Psychophysics: the study of
relationships between the physical characteristics of stimuli, such as their intensity, and psychological experience of them
Absolute threshold: the minimum stimulation needed to detect a particular stimulus
Signal detection theory: AT vary, not only on the signals strength, but also our psychological state……
Does Subliminal Stimulation Work?
Yes 1. The definition of absolute
threshold2. Sometimes we know more than
we think we do3. The experiment No no powerful, enduring effect on
behavior
Difference threshold — just noticeable difference jnd: the minimum difference that a subject can detect between two stimuli 50 percent of the time
Weber’s Law: I/I=k I: intensity
pitch-1/333; weight-1/50; taste-1/5
Sensory Adaptation—diminished sensitivity as a consequence of constant stimulation
The experiment (p.235;中文 p.163) An important benefit—it enables us to
focus our attention on informative changes in our environment without being distracted by the uninformative constant stimulation of garments, odors, and street noise.
Some exceptions: dark, and pain
Vision
Physical characteristics of
light
Sensory experience
wavelength Hue(色调)
Intensity (wave’s amplitude)
Brightness (亮度)
Purity Saturation (饱和度)
Localization of function in the brain
Artificially route visual information to the brain, thus restoring sight in the blind
“Seeing” does not take place in the eyes, so to hearing, smelling…… Seeing involves the entire eye-brain system
Visual Information Processing
Feature detection (p. 241)Parallel processing (p.242) —our brains do many things
at once, automatically and without our awareness
Color vision—if no one sees the tomato, is it red?
Young-Helmoholtz trichromatic (three-color) theory
Thomas Young, an English physicist (1802)
Helmoholtz (1857) —they inferred that the eye must
have three types of receptors, one for each primary color of light
Cannot explain r-g color blindness
Color Mixing—additive and subtractive
Opponent-process theory
Ewald Hering (physiologist, 1870)Afterimage There were 2 additional color
processes, one responsible for red vs. green perception, and one for blue vs. yellow.
Reconciling theories of color vision
Hearing
Physical characteristics of
sound
Sensory experience
Frequency Pitch
amplitude Loudness
Complexity Timbre
How do we perceive pitch
Place theory — high-pitched sounds
Frequency theory — low-pitched
volley principleConduction deafnessNerve deafness
Pain
Born without the ability to feel ~
Those who endure chronic ~What is pain? phantom limb pain— to see, hear, and feel, we
require not a body but a brain
Gate Control Theory (R. Melzack & Patrick wall, 1965, 1983)
The spinal cord contains a neurological “gate” that blocks pain signals or allows them pass on to the brain.
The activity of pain signals traveling up small nerve fibers—open
Activity in larger fibers or information comes from brain—close
Understanding Pain
Pain Control—it is indeed a physical and a psychological phenomenon
Anxiety Attention — distraction,
counterirrtation
Control Interpretation (cognitive
strategies) Application
Interaction of the sense
Synesthesia …………
Sensory Restriction or Deprivation
Disoriented, experience hallucinations?
Or it reduces stress and helps people become more open to positive influence? Foster our fulfillment?
REST—restricted environmental stimulation therapy