Unit 3: Sensation and Perception Flashcards
Sensation
the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment
Sensory receptors
sensory nerve endings that respond to stimuli
Perception
the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
** recognizing specific people in a crowd by their traits
Bottom-up processing
analysis that begins with the sensory receptors, and works up to the brain’s integration of sensory information
Top-down processing
information processing guided by higher-level mental processes; we construct perceptions by drawing on our experiences and expectations
Selective attention
The conscious focusing on one particular stimulus at a time
** hearing one voice amidst a sea of voices; cocktail party effect
Inattentional blindness
Failing to see visible objects when our attention is directed elsewhere
** think basketball player experiment with gorilla suit
Change blindness
- A form of inattentional blindness
- Failing to notice changes in one’s environment
** if someone is looking at a table and are interrupted by another brief visual, they will not notice a bottle of coke has been moved/taken away
Transduction
Conversion of one form of energy into another; in sensation, the transforming of stimulus energy (sights, sounds, etc.) into neural impulses the brain can interpret
Three steps of transduction
- RECEIVE: receiving sensory information, often using specialized receptor cells
- TRANSFORM: transforming that stimulus into neural impulses
- DELIVER: delivering that neural information to the brain
** light energy –> images/vision
Psychophysics
the study of relationships between the physical characteristics of stimuli (e.g. intensity) and our psychological experience of them
Absolute threshold
The minimum stimulus energy needed to detect a particular stimulus 50% of the time
**think tones experiment
Signal detection theory
- Relies on the idea that there is no one set absolute threshold/absolute threshold is dependant
- Theory that predict how/when we detect the presence of faint stimuli amid background stimuli, influenced by motivation, experience, expectations, alertness etc.
Subliminal
A stimulus below one’s absolute threshold for conscious awareness (cannot be detected 50% of the time)
Difference threshold
The minimum difference between two stimuli required for detection 50% of the time
Priming
Predisposing one’s memory/perception/response with the activation of certain associations (often happens unconsciously)
Weber’s Law
states that for an average person to perceive a difference in stimuli, two stimuli must differ by a constant minimum percentage rather than a constant amount
Sensory adaptation
diminished sensitivity as a consequence of constant stimulation
** someone’s perfume smells strong upon first meeting them, but you won’t notice a few minutes into the conversation
Perceptual set
- An influence on perception
- A mental predisposition to see one thing over another
** art that can be seen one of two ways, e.g. a dog or a family
Three influences on perception
- CONTEXT EFFECTS
The situation at hand dictates how we perceive our environment/similar environments in future - MOTIVATION
Motivation gives us energy to work towards our goals; things may look better, closer, or more appealing if we are motivated - EMOTION
How we feel during/about a situation can affect the appeal of any given situation
ESP
The controversial claim that perception can occur apart from sensory input
** clairvoyance, telepathy, precognition
Parapsychology
The study of paranormal psychological phenomena including ESP and psychokinesis
Pupil
The adjustable opening in the center of the eye through which the light enters
Iris
Controls the size of the pupil; a colored muscle that dilates or constricts in response to light intensity
Cornea
The eye’s clear and protective outermost layer covering the pupil and iris
Lens
The transparent structure behind the pupil that changes shape to help focus images on the retina
Optic Nerve
The nerve that carries neural impulses from the eye to the brain
Foeva
The focal point of the retina, around which the eye’s cones cluster
Retina
The light-sensitive inner surface of the eye containing receptors (rods and cones) plus layers of neurons that begin the processing of visual information
Blind spot
The point at which the optic nerve leaves the eye creating a “blind spot” where no receptor cells are present (the brain completes the missing part of the image)
Accommodation
The process by which the eye’s lens changes shape to focus near or far images onto the retina
Process of how we see
- Light enters the eye through the cornea and passes through the pupil; the iris dilates or restricts in response to light intensity
- The light hits the transparent lens, which focuses the image onto your retina using accommodation
- Millions of receptors (rods and cones) on the retina convert particles of light energy into neural impulses through transduction
- ^ Sparks neural signals in nearby bipolar cells, which activate nearby ganglion cells; the two twine together to form the optic nerve
- The optic nerve transmits information to the thalamus via the visual cortex, routing to detectors in the occipital lobe that organize neural firings into a conscious visual perception of the object
Rods
- Retinal receptors that detect greyscale (black/white/grey)
- Sensitive to movement
- Necessary for peripheral vision and twilight vision
- Humans have more rods than cones
Cones
- Retinal receptors that function in daylight/well-lit conditions
- Detect fine detail and give rise to color sensations
- Humans have less cones than rods
Young Helmholz Trichromatic Theory
- the retina contains three different types of color receptors; one sensitive to red, one to blue, and one to green
- when stimulated in combination, they can produce the perception any color
Opponent Process Theory
- Opposing retinal processes enable our vision
- e.g. red-green, black-white, blue-yellow
Feature detectors
Nerve cells in the brain’s visual cortex that respond to specific features of a stimulus, e.g. shape, angle or movement
Parallel processing
processing many aspects of a problem simultaneously; the brain’s natural mode of information processing
Gestalt
- a “gestalt” is an organized whole
- developed from a belief held by Gestalt Psychologists emphasizing our tendency to integrate pieces of information into meaningful wholes
Figure ground
the organization of the visual field into objects (figures) that stand out from their surroundings (ground/background)
Grouping
the perceptual tendency to organize stimuli into coherent groups
- proximity: grouping nearby figures together
- continuity: perceiving continuous patterns rather than segmented ones
- closure: filling in gaps to create a whole, complete object
Depth perception
the ability to see objects in three dimensions, although the images that strike the retina are two-dimensional
Visual cliff
a lab device for testing the depth perception of young animals and infants
- suggests an innate depth perception
Binocular cues
A depth cue that depends on the use of two eyes
Retinal disparity
The brain computes distance by comparing the retinal images from the two eyes. The greater the disparity/difference between the two images, the closer the objects
Monocular cues
A depth cue available to either eye alone
** interposition, linear perspective
Motion perception
computing motion based on the assumption that shrinking objects are retreating and enlarging objects are approaching
Phi phenomenon
An illusion created when two or more adjacent lights blink on and off in rapid succession
- our brain perceives a rapid series of slightly varying images as continuous movement
Perceptual constancy
Perceiving an object as unchanging even when illumination and retinal images change
** you know that a door is still a door/is the same door even when light/color change upon opening and closing it
Color constancy
Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
Size constancy
Perceiving an object as having an unchanging size, even as our distance from it varies
Perceptual adaptation
the ability to adjust to changed sensory input, including artificially displaced/inverted visual fields
** inverted lens: humans would initially throw a ball in the opposite direction of the net, but quickly adjust to throw more accurately despite the inversion
Audition
The sense or act of hearing
Pitch
A tone’s experienced highness or lowness – dependant on frequency
Frequency
The number of complete wavelengths to pass a point during a given time
Long wavelengths = low pitch, Short wavelengths = high pitch
Amplitude
The height from the peak to the trough of a wave
Tall amplitude = loud sounds, short amplitude = quiet sounds
How do we hear?
- The outer ear funnels sound waves to the eardrum
- The bones of the middle ear (hammer, anvil, and stirrup) amplify and relay the vibrations of the eardrum through the oval window of the fluid-filled cochlea
- Resulting pressure changes in the cochlear fluid cause the basilar membrane to ripple, bending the hair cells on its surface
- This triggers impulses at the base of the nerve cells, whose fibers converge to form the auditory nerve, which sends neural messages to the auditory cortex via the thamalus
Sensorineural hearing loss
- the most common form of hearing loss
- sometimes called “nerve deafness”
- damage to the cochlea’s receptor cells or to the auditory nerve
Conduction hearing loss
- less common form of hearing loss
- damage to the mechanical system that conducts sound waves to the cochlea
Cochlear implant
- a solution to “nerve deafness”/sensorineural hearing loss
- a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea
Place theory
The theory that we hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane
Frequency theory
- sometimes called the temporal theory
The theory that the brain reads pitch by monitoring the frequency of neural impulses moving up the auditory nerve: the rate matches the frequency of a tone, thus we can sense its pitch
How do we locate sounds?
Sound waves strike one ear sooner and more intensely than the other. We compute sound’s location with that information.
Four basic skin senses
Warm, cool, pressure, pain
Gate-control theory (pain)
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 activity from the brain.
How can we control pain?
Endorphins - natural painkillers
Placebo - mimicking painkilling medication to dampen the central nervous system’s attention/response
Gustation
Our sense of taste
Five taste sensations
Sweet, salty, sour, bitter, umami
Taste buds/taste bud regeneration
- 200 or more tastebuds containing 50-100 receptor cells each
- reproduce in a week or two (this decreases with age)
Why are children more sensitive to food?
Taste sensitivity decreases as you age as a result of slower/decreasing taste bud regeneration
Similarity/difference between taste and smell
- Both a chemical sense
- Smell bypasses the thalamus (straight to the olfactory bulb), and taste does not
How do we smell?
Olfaction happens when an external stimulus comes in contact with the receptor cells at the top of the nose, which transduce that information and pass it to the olfactory bulb
How are smell/taste and memory associated?
Taste/smell triggers memory because they are registered in parts of our brain not far from where the brain stores memories
Kinesthesia
Our movement sense - our system for sensing the position and movement of individual body parts
Vestibular sense
Our sense of body movement and position that enables our sense of balance
Sensory interaction
The principle that one sense may influence another, as when the smell of food influences it’s taste
Embodied cognition
The influence of gestures, bodily sensations and other states on cognitive preferences and judgements
