Download Retina Rods retina receptors that detect black, white, and gray

Retina
Rods retina receptors that detect black, white, and gray; needed for peripheral and twilight vision
Cones function in daylight /well-lit conditions. The cones detect detail, give rise to color sensations.
Optic nerve carries neural impulses from the eye to the brain.
Blind spot point at which optic nerve leaves eye, creating “blind” spot b/c no receptor cells are located
there.
Fovea the central focal point in the retina, around which the eye’s cones cluster. When light is focused
on fovea, you see color.
Visual Information Processing
Feature detectors nerve cells in brain that respond to specific features of the stimulus (shape, angle, or
movement, lines, curves, etc….discovered by Hubel&Weisel)
How visual information is processed: Sense-retinal processing-feature detectionparallel
processingrecognition (see and study figure 4.16 on page 131)
Color Vision
Young-Helmholtz trichromatic (three color) theory the theory that the retina contains three different
cone color receptors – one most sensitive to red, one to green, one to blue – which, when stimulated in
combination can produce the perception of any color.
Red – Green – Blue
Colorblindness:
Monochromatic =see only shades of grey
Dichromatic=cannot see red-green orBlue-yellow
This helps to support the next theory:
Opponent-process theory stated that sensory receptors in retina come in pairs (three sets of colors=redgreen, yellow-blue, white-black) enable color vision. If one sensor is stimulated, its pair is inhibited from
firing-explains Afterimage. Stare at red-switch gaze to blank page, will see green afterimage
Parallel Processing
Parallel processing =processing of many aspects of a problem simultaneously; the brain’s natural mode
of information processing for many functions; example=color, motion, form and depth of a bird
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Hearing-The Stimulus Input: Sound Waves *Audition (= the sense or
act of hearing)
Sound Waves=vibrations travel through air and collected by ear
Sound waves have Amplitude (height of the wave determines loudness, which is measured in decibels)
and
Frequency (length of waves and determines pitch-as in high and low pitch)
The Ear The ear is divided into the outer, middle and inner ear. The sound waves travel down the
auditory canal to the eardrum.
Middle Ear:
Eardrum = tight membrane that vibrates when struck by sound waves.
Bones of the middle ear = the hammer, anvil, stirrup which vibrate with the eardrum.
Oval window = where the stirrup connects to the cochlea.
Inner Ear:
Cochlea = a coiled, snail shaped, bony, fluid-filled tube in the inner ear through which sound waves
trigger nerve impulses. Neural messages sent to auditory cortex in temporal lobe
parts: Auditory nerve, cochlea, basil membrane (has hair cells)and oval window
Auditory nerve = nerve which sends the auditory message to the brain via the thalamusto auditory
cortex or temporal lobe
The Ear-Perceiving Pitch/Pitch Theories
Place theory=hair cells in cochlea respond to dif. Sound frequencies based on where they are located
Frequency theory= place theory explains hearing upper ranges of pitch only. Lower tones are sensed by
the rate at which cells fire. We hear pitch because hair cells fire at diff. rates (frequency) in cochlea
Hearing Loss
Nerve deafness=when hair cells in cochlea have been damaged, usually by loud noise; difficult to treat
since no way to regenerate hair cells
Conduction hearing loss=something goes wrong with other ear parts and getting sound to cochlea (with
ear canal, eardrum, hammer/anvil/stirrup or oval window)
Other Senses-Touch
Sense of touch activated when skin is indented, pierced, or has change in temp.
Types of touch:/Some nerve endings in skin respond to:
Pressure
Change in temperature (Warmth, cold, hot)
Pain (useful to warn of potential danger)
*High nerve concentration in fingers
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Kinesthesis=the system for sensing the position and movement of individual body parts.
Receptors in muscles & joints, and vision send brain messages
Vestibular sense= sense of balance and how body is oriented in space-located in Semicircular Canals in
inner ear-fluid moves in canals as position of head moves, then signal brain
Pain
Biological Influences:
Nociceptors =sensory receptors that detect hurtful temperature, pressures or chemicals
Gate-control theory = spinal cord contains a neurological “gate” that blocks pain signals or allows them
to pass on to the brain. Competing signals (such as rubbing) can temporarily reduce pain. Some pain
messages have a higher priority than others
Endorphins, or pain killing chemicals in body, also swing gate shut- Natural endorphins in brain
chemically similar to opiates
Phantom limb sensations-see page 144
Tinnitus-see page 144
Biophychosocial Approach to pain-see figure 4.2 on p. 145
Taste(or Gustation)
taste and smell are chemical senses –respond to chemicals rather than energy
Humans sense 4 types: Sweet, sour, salty and bitter
umami is new=protein (see p. 147, Table 4.2 for what taste indicates)
Taste buds mostly on tongue, but also on inside cheeks, roof of mouth
Taste smell and smell decrease with age
Sensory interaction= the principle that one sense may influence another, as when the smell of food
influences its taste, as with seeing and sound (read words I am hearing)
Smell (or Olfaction)
Chemical sense
Nerve fibers from Olfactory bulb connect to brain at amygdala and then to hippocampus (both connect
to emotional impulses/memory) –may be why smell is powerful memory trigger
Olfactory nerve, olfactory bulbs, olfactory membranes, olfactory receptor cells-see figure 4.28 on p. 149
Perceptual Organization
Gestalt (form or whole) an organized whole. Gestalt psychologists emphasized our tendency to
integrate pieces of information into meaningful wholes or groups-this is innate and inevitable.
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Figure-ground =tendency to view certain figures of a scene as figures and the rest as a background
grouping stimuli together:
Proximity-things near each other are related
Similarity-things that resemble each other are related
Continuity-things that form a flowing line are viewed as continuous rather than broken up
Connectedness perceive things as single units
Closure –we fill in gaps to create a complete an object
Depth Perception
Depth perception =the ability to see objects in three dimensions although the images that strike the
retina are two-dimensional; allows us to judge distance.
Visual-cliff =a laboratory device for testing depth perception in infants and young animals
Believed to be initiated in infants with crawling; believed to be innate
Binocular cues depth cues, such as retinal disparity, that depend on the use of two eyes
Retinal disparity=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 are either Mononocular or binocular Cues
Monocular cues
Relative height-things higher seem taller
Relative size-closer items appear bigger
Interposition-something that blocks another item is perceived as closer
Linear perspective-parallel lines seem to converge with distance
Relative motion-objects that are stable appear to move as we move (in a car)
Perceptual Constancy
Perceptual Constancy =perceiving objects as unchanging (having consistent shapes, size, lightness, and
color) even as illumination and retinal images change. Size, shape and brightness are types of constancy
(two rectangular tables in different positions are seen as the same sized table or door seems same
shape/size regardless of angle)
Size constancy-closer objects look bigger, but we take distance into account
Ex: Moon illusion
Lightness/Brightness constancy=we perceive object as a constant color even after reflective light
changes
Color constancy perceiving familiar objects as having consistent color, even if changing illumination
alters the wavelengths reflected by the object.
Perceptual adaptation/Sensory Habitation: our perception of sensations is patricianly determined by
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how focused we are on them
Ex: I do not hear the sounds out my apartment window.
Motion Perception
Stroboscopic movement: Phi phenomenon =an illusion of movement created when two or more
adjacent lights blink on and off in quick succession. Ex: neon, blinking arrow sign
Perceptual Set (experiences, assumptions, expectatios)
Perceptual set a mental disposition to perceive one thing and not another. What establishes our
perceptual sets?:
-Mental predisposition (Schemas-try to fit things into existing ones) that greatly influences what we see
Context effects (our brain interprets info, say words, in the context in which they are heard or seen: die
v dye, mourning v morning)
Emotion and Motivation impact our perceptual set
Perception is a Biopsychosocial Phenomenon-see page 165
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