the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
analysis that begins with the sensory receptors and works up to the brain's integration of sensory information
the information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations
- the study of relationships btween the physical characteristics of stimuli, such as their intensity, and our psychological experience of them
- *"You are physically psycho to stimuli when you experience them"
the minimum stimulation needed to detect a particular stimulus (light, sound, pressure, taste or odor) 50% of the time
below one's absolute threshold for conscious awareness
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or reponse
the minimum difference btwn two stimuli required for detection 50% of the time. We experience the difference threshold as a just noticeable difference (jnd)
the principle that, to be perceived as different, two stimuli must differ by a constant minimum % (rather than a constant amount)
diminished sensitivity as a consequence of constant stimulation
interrupts the brain's processing before conscious perception
Because sometimes we feel what we do not know and cannot describe...
Much of our information processing occurs automatically, out of sight, off the radar screen of our conscious mind
For the average person to perceive differences...
- two lights must differ in intensity by 8%
- two objects must differ in weight by 2%
- two tones must differ in frequency by only 0.3%
We perceive the world not exactly as it is...
but as it is useful for us to perceive it
- the distance from the peak of one light or sound wave to the peak of the next.
- Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission
- the dimension of color that is determined by the wavelength of light
- what we know as the color names blue, green, and so forth
the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude
Two physical characteristics of light which help determine our sensory experience
Wavelength, and intensity
- the number of complete wavelengths that can pass a point in a given time, depends on wavelength
- shorter the wavelength, the figher the frequency
- the height from peak to trough
- in vision, it determines the intensity of colors
- In hearing, it applies to the strength of sound waves, which determines the loudness
- what light passes through to enter the eye
- protects the eye and bends light to provide focus
- a multilayered tissue on the eyeball's light sensitive inner surface.
- contains receptor rods and cones plus layers of neurons that begin the processing of visual information
a process by which the lens focuses the rays by changing it's curvature
path of a light-energy particle into your eye
- first it would make its way through the retina's outer layer of cells to it's buried receptor cells, rods and cones
- there, you would see the light energy trigger chemical changes which spark a neural impulse, activating bipolar cells
- bipolar cells would then activate the ganglion cells
- from there, following the path of the ganglion cells axons which form optic nerve which carries info to brain
- retinal receptors that detect black, white, and gray
- necessary for peripheral and twilight vision, when cones don't respond
- don't have a "hotline" to brain, share bipolar cells w other rods, sending combined messages
- retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions.
- detect fine detail and give rise to color sensations
- Many have their own "hotline" to the brain; bipolar cells which help relay a cones individual message to the visual cortex
the nerve that carries neural impulses from the eye to the brain (where the thalamus will receive and distribute the info)
the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there
the central focal pint in the retina, around which the eye's cones cluster
How does the brain receive and process visual information?
- After processing by retina's nearly 130 million rods and cons, info travels to bipolar cells, then to ganglion cells & through their axons which make up the optic nerve, to the brain.
- Any given retinal area relays info to corresponding location in visual cortex, in occipital lobe.
nerve cells in the brain that respond to specific features of a stimulus, such as shape, angle, or movement
- doing many things at once
- the processing of many aspects of a problem simultaneously;
- the brain's natural mode of information processing form many functions, including vision.
- Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.
a localized area of blindness in part of the field of vision
Young-Helmholtz trichromatic (three-color) theory
the theory that the retina contains three different color receptors -- one most sensitive to red, one to green, and one to blue -- which, when stimulated in combination, can produce the perception of any color
Explain why people with color-deficient vision are not actually "colorblind"
- They simply lack functioning red- or green- sensitive cones, or sometimes both.
- Their vision is either monochromatic (one color) or dichromatic (two color) instead of trichromatic (3 color), making it impossible to distinguish red and green.
- Dogs also lack receptors for red
- By Hering, the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision.
- For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green
The physical characterstic of light that determines the color we experience, such as blue and green, is..
The mystery of color vision:
- Color processing occurs in two stages:
- The retina's cones for red, green, and blue respond in varying degrees to different color stimuli (as in Young-Helmholtz theory)
- The cones' signals are then processed by the nervous system's opponent-process cells, en route to the visual cortex
- the sense of hearing
- highly adaptive
- a tone's experienced highness or lowness; depends on frequency
- Short waves have high frequency and high pitch
- Long waves have low frequency and low pitch
How sound is measured
- in decibels
- The absolute threshold for hearing arbitrarily defined as zero decibels.
- Every 10 decibels correspond to tenfold increase in sound intensity
- Normal conversation is 60 decibels/ a whisper is 20 decibels
the chamber btwn the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup which make up a piston) that concentrate the vibrations of the eardrum on the cochlea's oval window
a coiled,snail-shaped, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses
the innermost part of the ear, containing the cochlea, semicircular canals, and vestivular sacs
How the ear transforms sound energy into neural messages
- First, outer ear channels sound waves though auditory canal to eardrum (tiny membrane which vibrates w/ the waves)
- Next, the middle ear transmits the eardrum's vibrations through bones to oval window (the cochlea's membrane) jostling the fluid in the tubes.
- This motion ripples in the basilar membrane, bending the hair cells which triggers impulses from adjacent nerve cells, whose axons converge to form auditory nerve, which sends neural messages (via thalamus) to temporal lobe's auditory cortex
What accounts for most hearing loss?
damage to hair cells
how does the brain interpret loudness
from the number of activated hair cells
- the system for sensing the position and movement of individual body parts
- Enabled by important sensors in joints, tendons, bones, and ears, as well as skin
- the sense of body movement and position, including the sense of balance
- The semicircular canals, which look like 3D pretzel, and the vestibular sacs, which connect the canals with the cochlea, contain fluid that moves when your head rotates or tilts
The basic four skun sensations
- pressure, warmth, cold, and pain
- Only pressure has identifiable receptors
sensory receptors that detect hurtful temps, pressure or chemicals
the theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain
- a ringing the the ears sensation
- associated with the phantom sounds people with hearing loss often experience as the sound of silence
How do we edit our memories of pain
- people tend to over look pains duration. Their memory snapshots instead record two factors:
- 1- people tend to record pain's peak moment, which leads them to recall variable pain, with peaks as worse
- 2 - they register how much pain the felt at the end
5 basic taste sensations
- sweet, sour, salty, bitter, and umami (the savory meaty taste, MSG)
- TASTE IS A CHEMICAL SENSE
The survival functions of basic tastes
- Sweet ~ energy source
- Salty ~ Sodium essential to physiological processes
- Sour ~ Potentially toxic acid
- Bitter ~ potential poisons
- Umami ~ Proteins to grow and repair tissue
reproduction of taste receptors
- reproduces every week or two
- however, as you grow older, the number of taste buds decreases, as does taste sensitivity
- smoking and alcohol use accelerate these declines
- Those who lose their sense of taste report food tastes like "straw" and is hard to swallow
- the principle that one sense may influence another, as when smell of food influences it's taste
- smell + texture + taste = flavor
- the idea that we may perceive a third syllable when we see a speaker saying one syllable while we hear another
- Ex: Seeing the mouth movements for ga while hearing ba, we may perceive da
- an organized whole
- gestalt psychologist empasized our tendency to integrate pieces of information into meaningful wholes
- German for "whole" or "form"
the organization of the visual field into objects (the figures that stand out from their surroundings (the ground)
the perceptual tendency to organize stimuli into coherent groups
Our minds rules for grouping
- Proximity ~we group nearby figures together
- Similarity ~ we group similar figures together
- Continuity ~ we perceive smooth, continuous patters rather than discontinuous ones.
- Connectedness ~ (two dots & line in book) because they are uniform and linked, we perceive each set as a single unit
- Closure ~ We fill in gaps to create a complet, whole object
the ability to see objects in 3 dimensions although the images that strike the retina are 2-dimensional; allows us to judge distance
a lab device for testing depth perception in infants and young animals
depth cues, such as retinal disparity, that depend on the use of two eyes
a binocular cue for perceiving depth: By comparing images from the retinas in the two eyes, the brain computes distance - the greater the disparity (difference) between the two images, the closer the object
depth cues, such as interposition and linear perspective, available to either eye alone
horizontal - vertical illusion
our perceiving vertical dimensions as longer than identical horizontal dimensions
relative height illusion
a monocular cue: we perceive objects higher in our field ov vision as farther away.
A monocular cue: If we assume two objects are similar in size, most people perceive the one that casts the smaller retinal image as further away
A monocular cue: If one object partially blocks our view of another, we perceive it as closer.
A monocular cue: parallel lines appear to converge w distance. The more they converge, the greater their perceived distance
Light and shadow
- a monocular cue: nearby objects reflect more light to our eyes. Thus, given two identical objects, the dimmer one seems farther away.
- Shading, too, produces a sense of depth consistent with our assumption that light comes from above.
A monocular cue: as we move, objects that are actually stable may appear to move.
perceiving objects as unchanging (having consistent shapes, size, lightness, and color) even as illumination and retinal images change
we can perceive the form of familiar objects as constant even while our retinal image of it changes
we can perceive objects as having a constant size, even while our distance from them varies
also called brightness constancy; we perceive an object as having a constant lightness even while it's illumination varies
the amount of light an object reflects relative to it's surroundings
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
in vision, the ability to adjust to an artificially displaced or even inverted visual field
a mental predisposition to perceive one thing and not another
- guide our perception of lightness and color; also shapes perception in other ways.
- Ex: the 2 monsters in the textbook pic
ESP; the contoversial claim that perception can occur apart from sensory input; includes telepathy, clairvoyance, and precognition
mind-to-mind communication; one person sending thoughts to another person or perceiving another's thoughts
perceiving remote events, such as sensing that a friends house is on fire
perceiving future events
mind over matter... such as levitating a table or influencing a roll of a die
the study of paranormal phenomena, including ESP and psychokinesis