Chapter 4 Flashcards
Sensation
the stimulation of sensory receptors and the transmission of sensory information to the central nervous system
i. Sense receptors are the specialized neural cells in sense organs that respond to stimuli and change physical energy into neural impulses
ii. The process of stimulus info being converted into a neural impulse that the brain can interpret is called transduction
iii. Sensation is mechanical… it just happens
transduction
The process of stimulus info being converted into a neural impulse that the brain can interpret is called
Perception
the process by which sensations are organized into an inner representation of the world by the brain
i. Perception is not mechanical - involves more than sensations; it reflects learning and expectations and organization of information
Perception and sensation flow continuously - broken down into bottom up and top down processing
Schema
Your personal reality, based on concepts and prior knowledge
i. Your body detects some form of energy -> the energy is transduced into neural activity -> the brain interprets the info and produces perception of the sense
Bottom - up processing
i. Is basic sensory processing and works up to higher levels of processing (how we process when we have no prior knowledge); external content
Top - down processing
i. Constructs perceptions from this sensory input by drawing on your culture, experiences, and expectations (how we process if we have prior knowledge); internal factors
Attention
an interaction of sensation and perception that is affected by internal and external processes
Selective attention
the focusing of conscious awareness on a particular stimulus
Cocktail Party Effect
our ability to attend to mentions of our name or specific topics in loud, distracting environments
Inattention
failing to perceive when our attention is directed elsewhere
i. It is a by-product of what we are really good at: focusing our attention on some part of our environment
Change blindness
failing to notice changes in the environment (a form of inattention)
Absolute Threshold
minimum amount of stimulus that must be present to produce a sensation 50% of the time
Signal-detection theory
idea that the perception of stimuli involves not only the strength of the stimuli, but also the interaction of physical, biological, and psychological factors
Just Noticeable difference
minimal amount of difference in intensity between two stimuli so that they will be perceived as being different; aka Differences threshold
i. Example: Take two cans of same red paint. Add drops of white to the point at which the difference between the paints is first barely detectable
Weber’s Law
the minimal percentage by which a source of physical energy must be increased or decreased so that a difference in intensity will be perceived… it is a constant proportion to initial stimulus
Sensory Adaptation
sensory change in response to environmental stimuli (i.e.… becoming more/less sensitive to stimuli); tends to be physiological
Perceptual set
a mental predisposition to perceive one thing and not another
Synesthesia
a condition in which one sense is simultaneously perceived as if by once or more additional senses
i. Just about any combination of senses is possible, and no two people really experience it the same way
Synesthesia Diagnosis
i. It just happens - not something that has to be thought about to perceive
ii. Must be the same experience every time
Vision
○ Your brain makes sense of colors, shapes, symbols, depth, and movement by putting the information together like a jigsaw puzzle – into something coherent
○ Optical illusions work by exploiting the mind’s tendency to try to find order in patterns (tapping into it’s stored information)
Light
stuff that triggers visual sensations; described in terms of wavelengths
○ The hue (color) we perceive in light depends on its wavelength, while its intensity (brightness) depends on the light wave’s amplitude
Cornea
transparent tissue forming outer surface of eyeball; light 1st passes through this into your fluid-filled eye
Iris
colored part of the eye; muscle that determines amount of light that passes through pupil
Pupil
the black opening in the iris; size adjusts automatically to the amount of light; is also sensitive to emotional responses
Lens
transparent body behind the iris/pupil that focuses an image on the retina; adjusts to an image by changing its thickness
i. When people squint to focus near or far, they are adjusting the thickness of the lens (accommodation)
ii. Nearsightedness - when the lens focusses objects in front of the retina
iii. Farsightedness - when the lens focusses objects behind the retina
Retina
light-sensitive photoreceptor cells and layers of neurons that begin processing visual information
Fovea
area of central focus in the retina; just above optic nerve; cones cluster in and around it (makes peripheral vision a poor judge of color)
optic nerve
a bundle of axons from a specific type of cells called ganglion cells
Millions of retinal photoreceptor cells convert light energy into neural impulses which are sent to the brain via the **
Blind spot
point where eye is insensitive to visual stimulation; where optic nerve exits to the brain
Rods
photoreceptors sensitive only to intensity of light; allow us to see only in black, grey, and white
Cones
photoreceptors that provide color vision and detect fine detail
Dark Adaptation
the process of adjusting to conditions of lower lighting by increasing the sensitivity of rods and cones
Light Adaptation
the adjustment of the visual system to perform best based on overall lighting conditions (i.e. attempts to keep rods from over-saturating as lighting increases)
Trichromatic theory
theory that the retina contains three types of color receptors; when stimulated in combination, they can produce the perception of any color
Color Blindness
(Color Vision Deficiency)
i. CVD is caused by damage or irregularities to various cones or ganglion cells
ii. Trichromatic - normal color vision
iii. Monochromatic - sensitive to light and dark only; total colorblindness
iv. Dichromatic - discriminate only 2 colors - blues & yellows or reds & greens; partial colorblindness; the color one is deficient in is seen as a muted grey or brown
Opponent - process theory
theory that opposing retinal processes (red-green, blue-yellow, black-white) enable color vision. [If one is stimulated, the other is inhibited]
Afterimage
The lingering visual impression made by a stimulus that has been removed
i. In afterimages, persistent sensations of color are followed by perceptions of the complementary color when the color is first removed [due to sensory fatigue of the ganglion cells]
Feature detectors
nerve cells in the occipital lobe that respond to specific features of a stimulus (such as shape, angle, or movement)
i. fMRI scans have been used to map out different brain areas activated by viewing various objects
ii. Brain activity is so specific, researchers can ‘tell’ whether a person is looking at a shoe, chair, or face from a pictorial list based on the pattern of brain activity
Blindsight
a condition in which a person can respond to a visual stimulus without consciously experiencing it
Prosopagnosia
a condition in which the affected has an impaired ability to recognize familiar faces, including their own; aka face blindness
i. Caused by lesions to specific parts of the occipital and temporal lobes
ii. If the condition is acquired (not congenital/developmental), they are usually able to recognize facial expressions/emotions
Gestalt Psychology
○ In the early 1900s, a group of German psychologists noticed that people who are given a cluster of visual information tend to organize the bits and pieces into a meaningful whole
○ Helps explain how we organize our perceptual world
○ Closure - The tendency to perceive a broken figure as being something complete or whole
Figure-ground perception
Form Perception
separating figures/objects against backgrounds
Grouping
Form Perception
the perceptual tendency to organize stimuli into coherent groups
Proximity
Form Perception
nearness
Similarity
Form Perception
perceptual tendency to group objects that are similar in appearance
Depth perception
the ability to judge distance, and see objects in three dimensions even though the images that strike the retina are two dimensional
Visual cliff
Depth perception
a laboratory device for testing depth perception in infants and young animals
Monocular depth
cues that can be perceived by one eye to create an illusion of depth
Interposition
Linear Perspective
Texture gradient
Relative size
Relative clarity
Interposition
overlapping; placing one object in front of another
Linear Perspective
viewing lines as coming together as they recede from us into the distance; forms triangular shapes in our mind
Texture gradient
changes in the appearance of texture elements as objects recede into the distance (size, density, clarity)
Relative size
the ability to judge how far away something is based on how big or small they are in relation to objects one has interacted with in the past
Relative clarity
depth is determined by noting distant objects as less sharp/focused
Binocular Depth
cues that involve both eyes; also help us perceive depths
Comes from the fact that our eyes are separated about 2.5 inches apart
Retinal disparity
Convergence
Retinal disparity
as an object nears your eyes, you begin to see two images (with each retina receiving a different view of the same three-dimensional object)
Convergence
merging of two retinal images by the brain to form a single image
Motion Perception / Apparent Movement
○ Visual perception of movement is based on change of position relative to other objects
Stroboscopic Motion
Phi Phenomenon
Stroboscopic Motion
the illusion of motion is generated by a series of stationary images changing rapidly
Phi Phenomenon
occurs when an on-off process is perceived as movement
Perceptual Constancy
recognition that objects are unchanging (having a consistent color, shape, or size) even as the visual field changes
Perceptual adaptation
the ability to adjust to a changed sensory input (such as inverted or adjusted visual field - getting new glasses and feeling dizzy for a bit but then it adjusts)
Hearing
○ Hearing (audition) provides us with nearly as much useful information about our environment as vision
○ Sound, or auditory stimulation, travels through the air as waves
Frequency
the number of complete wavelength cycles per second
Pitch
perceived tone level, based on frequency
i. Usually expressed as musical notation
ii. The greater the number of cycles per second, the higher the pitch of the sound
Loudness
determined by the height/ amplitude of sound waves
The Ear Characteristics
○ The human ear has many uses. It is shaped to capture sound waves, to vibrate in sync with them, and to transmit all this business to the brain
○ We utilize our two ears in helping to locate sound
○ Sound waves strike one ear sooner and more intensely than the other. The brain analyzes these minute differences and computes the source
Outer; Middle; Inner Ear
shaped to funnel sound waves in to other parts of the ear; eardrum hammer, anvil, and stirrup; cochlea, hair cells, and auditory nerve
Place Theory
The brain interprets a pitch by decoding the various places where the sound wave stimulates the cochlea -> wired to different parts of the auditory cortex so they are processed correctly; better explanation for higher frequencies
Frequency Theory
Proposes that the brain deciphers frequency based on neural firing rate in the auditory systems; the better explanation for lower frequencies
Volley Theory
Separate neurons of the auditory system fire out of sync with one another but combine (phase-lock) to mimic a frequency
Hearing Impairment
Hearing difficulties can result from aging or various damage to the auditory structures
- Conduction deafness
- Sensorineural/ Sensory-neural deafness
Conduction Deafness
caused by damage to the outer ear or middle ear (doesn’t conduct sound to cochlea); sounds seem faint/mutes
i. Use of hearing aids helps, and sometimes surgery can replace the bones with plastic versions
Sensorineural/ Sensory-neural deafness
damage to the inner ear (most often damage to cochlea, such as loss of hair cells which will not regenerate)’ sometimes damage to auditory nerve
- Cochlear implants
Cochlear Implants
the implants, wired into the cochlea’s nerves, translate sounds into electrical signals
Help sensory-neural deafness
Sensory Interaction
the principle that our sensory systems constantly work together and may influence another
Smell
- Olfaction
○ Smell is a chemical sense -> the stimuli for it are molecules of chemical compounds bobbing around in the air
○ We have abt 20 million olfactory receptors in the nasal cavities which respond selectively to specific odorants or combinations of them (think cookies in the oven, smoke from a fire)
○ The number of receptors stimulated determines the strength of the smell
i. Olfactory neurons bypass the brain’s sensory control center (thalamus) and are sent to the temporal lobe’s primary smell cortex, near the hippocampus - may explain why smells trigger memories
Olfactory Nerve
sends information about odor to the brain
Anosmia
smell blindness/smell deficit
Pheromones
chemical secretions that are detected (but are imperceptible to the conscious sense of smell); they stimulate reproductive behaviors in members of a species
Taste
- Gustation
○ Taste is a chemical sense because the stimuli for it are molecules of chemical compounds - taste receptors then transmit a message to a partner cell in the temporal lobe
i. Taste is sensed through taste receptors, mostly located on your 10,000-ish taste buds (but you also have thousands of receptors on the inside of your mouth)
ii. The # of taste receptors you have is related to classifying your taste sensitivity: Supertasters, Medium Tasters, or Nontasters (just diminished) - the designation comes from being able to taste the chemical Propylthiouracil
Taste Qualities
Sweet
Sour
Salty
Bitter
Umami (Japanese - savory)
Oleogustus (Latin - taste of fat)
Flavor of food also depends on its color, odor, texture, and temperature
Touch Sensory System
○ Skin can discriminate touch, pressure, temperature, and pain
A self-administered tickle produces less sensory cortex activation than being tickled by someone else -> cognition influences our brain’s sensory response
- Temperature
- Pain
Temperature - sensory
i. Receptors for warm and cold temperatures are located just beneath the skin - the sensation of ‘hot’ is produced by the activation of both warm and cold receptors
Pain - sensory
i. A signal that something is wrong in the body
ii. Originates in the point of contact -> a message is sent to the brain by the release of various chemicals
It is interesting that pain receptors can be found inside our body, not just outside
- Gate-Control Theory
- Phantom-limb sensation
vi. Controlling Pain
i. In response to pain (or even vigorous exercise), the brain triggers endorphins -> neurotransmitter that acts similar to morphine
Gate-Control Theory
the spinal cord contains a neurological ‘gate’ that blocks or allows pain signals to pass to the brain
i. Only a limited amount of stimulation can be processed by the nervous system at one time, so rubbing/scratching/etc. means that our body transmits more sensations to the brain that, in a sense, compete for neurons
Phantom-limb sensation
after the loss of a limb, people report sensation or pain where the limb used to be
It is thought that the overload of information leaves the pain circuit “gates” open
Kinesthesia
a sense that informs us about the positions and motions of our body (aka Proprioception)
i. Sensory information is fed back to the brain from sensory organs in the joints, tendons, and muscles
Vestibular Sense
the sense of equilibrium/balance that informs us about our bodies’ position relative to gravity
i. The biological gyroscopes for this sense are the semicircular canals in your inner ear that send nerve signals to your cerebellum
