==Sensation== - the detection of physical energy emitted or reflected by physical objects
==Perception== - processes that organize sensory impulses into meaningful patterns
Introduction to the senses
a. There are five widely known senses and other lesser known senses
b. All senses evolved to help us survive
Sense receptors stimulate sensory neurons which stimulate brain cells
Encoding the electrical messages - the nervous system uses two kinds of codes
a. Anatomical codes
b. Functional codes
==Synesthesia== occurs when stimulation of one sense evokes sensations in another
==Psychophysics== - how the physical properties of stimuli are related to our psychological experience of them
==Absolute threshold== - the smallest amount of energy a person can detect reliably (50 percent of the time)
==Difference threshold== - the smallest difference in stimulation that a person can detect reliably (50 percent of the time); also called just noticeable difference (jnd)
==Signal detection theory==
a. Accounts for response bias (tendency to say yes or no to a signal)
b. Separates sensory processes (the intensity of the stimulus) from the decision process (influenced by observer’s response bias)
Decline in sensory responsiveness occurs when a stimulus is unchanging; nerve cells temporarily stop responding
Sensory deprivation studies
a. Early deprivation study subjects became edgy, disoriented, confused, restless and had hallucinations
b. Early studies exaggerated negative reactions
Brain requires minimum stimulation to function normally
Stimulus for vision is light, which travels in waves
Characteristics of light waves
a. ==Hue== - color that is related to wavelength
b. ==Brightness== - intensity, corresponds to amplitude of the wave
c. ==Saturation== - colorfulness and complexity of the range of wavelengths
Psychological dimensions of visual experience are hue, brightness, saturation
Physical properties of light are wavelength, intensity, complexity
==Cornea== - front part of the eye; protects the eye and bends light rays toward lens
==Lens== - located behind the cornea; focuses light by changing curvature
==Iris== - muscles that control the amount of light that gets into the eye
==Pupil== - round opening surrounded by iris; widens and dilates to let light in
==Retina== - located in the back of the eye, contains visual receptors
a. Parts of retina
(1) Two types of receptors
(2) ==Fovea== - center of retina, sharpest vision, contains only cones
b. Processing visual information
(1) ==Dark adaptation== - time it takes to adjust to dim illumination; reflects mainly increase in sensitivity of rods
(2) Rods and cones connect to bipolar neurons that connect to ==ganglion cells==, whose axons converge to form optic nerve, that carries information out of the eye to the brain
(3) ==Optic nerve== - leaves the eye at optic disc; no rods or cones; blind spot on retina
==Trichromatic (Young‐Helmholtz) theory==
a. This approach applies to the first level of processing (in the retina)
b. Retina contains three types of cones: one responds to blue, another to green, another to red; these combine to make all colors c. People with color deficiencies lack particular types of cones
==Opponent‐process theory==
a. Second stage of color processing in the ganglion cells of the retina and neurons in the thalamus and visual cortex (opponent process cells)
b. They turn off to one wavelength in a pair and on to the other
c. Another opponent‐process system responds in opposing fashion to black and white, providing information about brightness
d. Opponent‐process theory can explain why we see negative afterimages
Perceived color of an object also depends on the wavelengths reflected by the other objects around it
==Visual perception== - the mind interprets the retinal image and constructs the world using information from other senses
Form perception
a. Gestalt psychologists studied $$how people organize the visual world into meaningful
patterns$$
b. Strategies for building perceptual units include use of: figure/ground distinction,
proximity, closure, similarity, and continuity
==Depth and distance perception== - object’s location inferred from distance or depth cues
a. ==Binocular cues== - dependent on information from both eyes
(1) Changes in angle of convergence of the image seen by each eye provide distance cues
(2) ==Retinal disparity== - disparity in the lateral separation between two objects as seen by the two eyes is used to infer depth or distance
b. ==Monocular cues== ‐ cues that do not depend on using both eyes include interposition and linear perspective
Visual constancies: When seeing is believing
a. ==Perceptual constancy== - our perception of objects is unchanging though the sensory patterns they produce are constantly shifting
b. ==Visual constancies== ‐ shape, location, size, brightness, and color
==Visual illusions== - When seeing is misleading; visual constancies may occasionally fool us, resulting in visual illusions
Stimulus for sound is a wave of pressure created when an object vibrates; that causes
molecules in a transmitting substance (such as air) to move
Characteristics of sound waves
a. ==Loudness== - intensity of a wave’s pressure; corresponds to amplitude; also affected by
pitch; units of measure are decibels
b. ==Pitch== - frequency (and intensity) of wave; units of measure are hertz (cycles per second) c. ==Timbre== ‐ complexity of wave; the distinguishing quality of a sound
3. When all frequencies of the sound spectrum are present, white noise occurs
Chemicals stimulate receptors (inside taste buds) on tongue, throat, and roof of mouth
a. ==Papillae== - bumps on tongue, contain taste buds
b. ==Taste receptors== are replaced every 10 days; number of taste buds and receptor cells declines with age
==Four basic tastes==: salty, sour, bitter, sweet
a. Each taste produced by a different type of chemical
b. Each can be perceived wherever there are receptors
c. Flavors are a combination of the four, but unclear how this occurs
d. ==Natural tastes== - preference for sweet
e. ==Taste== is influenced by smell, culture, individual differences, temperature, texture
f. There are genetic differences in sensitivity to certain tastes
==Skin== protects innards, helps identify objects, involved in intimacy, serves as boundary
==Skin senses== include: touch (pressure), warmth, cold, and pain
a. No correspondence between four sensations and types of receptors, except for pressure
b. Many aspects of touch continue to baffle scientists
Pain differs from the other skin senses in that removal of stimulus doesn’t always terminate sensation
==The neuromatrix theory of pain==
a. Gate‐control theory ==can't explain phantom pain==
(1) The brain can generate pain without external stimulation
(2) The neuromatrix gives us a sense of our own bodies
(3) Abnormal activity can occur in the ==neuromatrix== as a result of memories and expectations
Studies with animals show that experience during a critical period may ensure survival
of skills present at birth
Research concludes that infants are born with many perceptual abilities
a. Ability to detect edges, angles, sizes, and colors
b. Visual cliff experiment shows depth perception by two months of age
c. Taste and smell preferences, ability to discriminate odors, distinguish voices from
other sounds, localize sound is present early
Reported ==ESP experiences== include telepathy and precognition
Evidence or coincidence?
a. Most “evidence” for ESP comes from unreliable anecdotal accounts
b. ==Parapsychology== - field concerned with the study of ESP
c. Studies under controlled conditions by parapsychologists
(1) Some positive results found but there were methodological problems and results have not been replicated
(2) There is presently no empirical evidence to support the existence of any of the phenomena included in the definition of ESP
Magicians' trick us by relying on the tendency of the mind to impose its own interpretation on perceptions
\