Sensations And Perception Flashcards
What are sensations
The stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain
What does perception mean
Making sense of what our senses tell us
What is psychophysics
The scientific area that studies relations between the physical characteristics of stimuli and sensory capabilities
What is the absolute threshold
The lowest intensity at which a stimulus can be detected 50% of the time
What is decision criterion
A standard of how certain they must be that a stimulus is present before they will say they detect it
What is signal detection theory concerned with
The factors that influence sensory judgement
What is a subliminal stimulus
As stimulus that is so weak or brief that although it is received Blythe senses it cannot be perceived consciously
What is the difference threshold
The smallest difference between two stimuli that people can perceive 50% of the time
What is Weber’s law
The difference threshold is directly proportional to the magnitude of the stimulus with which the comparison is being made
What is sensory adaption
Diminishing sensitivity to a stimulus
What is transduction
The process whereby the characteristics of a stimulus are converted into nerve impulses
Where do light wave enter the eye
Through the cornea
What is the pupil
An adjustable opening behind the cornea that controls the amount of light that enters the eye
What is the lens
A flexible structure that becomes thinner to focus on distant objects and thicker to focus on merely objects
Where is the retina located
The back of the eye
What is accommodation
When an image is focused directly and sharply onto the retina and determines good all round vision
Want is myopia
Nearsightedness
What happens in myopia
The visual image is focused in front of the retina
What is the cause of myopia
The eyeball is longer than normal
What is hyperopia
Farsightedness
What occurs in hyperopia
The image is focused behind the retina
What causes hyperopia
The lends doesn’t thicken enough
What is the retina
A multilayered light sensitive tissue at the rear of the fluid filled eyeball
What two light sense tie receptor cells does the retina contain
Rods
Cones
What are rods
Black and white brightness receptors
When do rods function best
In dim light
What are cones
Colour receptors
When do cones function best
In bright illumination
What is the fovea
A small area in the centre of the retina that contains no rods but many densely packed cones
What is the fovea responsible for
Our most detailed vision
What creates a blind spot
An absence of photoreceptors where the optic nerve exits the eye
What is the optic nerve
Ganglion cells whose axons are collected into a bundle to form the optic nerve
What are photopigments
Protein molecules that allow rods and cones to translate light waves into nerve impulses
What is dark adaption
The progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination
What are feature detectors
Cells within the primary visual cortex that fire selectively in response to visual stimuli that have specific characteristics
What is transduction
The process whereby the characteristics of a stimulus are converted into nerve impulses
What are sound waves
Pressure waves travelling through any medium that will allow their conduction
What are two characteristics of sound waves
Frequency
Amplitude
What us frequency
The number of sound waves or cycles per second
What range of sound frequencies can humans detect
20 to 20000 Hz
What is amplitude
The vertical size of sound waves
What are decibels
The measure of the physical pressures that occur at the eardrum
What is the pinnae
The visible part of the ear that resides outside the head
What is the function of the pinnae
To collect sound and help localise where sounds are coming from
What are the bones in the middle ear collectively called
The ossicles
What are the three ossicles
The hammer
The anvil
The stirrup
What is the role of the ossicles
Impedance matching
What does impedance mean
How much a given medium impedes sound waves
What does the inner ear contain
The cochlea
What is the cochlear
A coiled, fluid filled tube
What is the basilar membrane
A sheet if tissue that runs the length of the cochlea
Where is the organ of Corti
On the basilar membrane
What is in the Corti
Thousands of tiny hair cells that are the actual cell receptors
What is the theory of pitch perception
Nerve impulses sent to the brain match the frequency of the sound wave
What is the place theory of pitch perception
The specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue
What are the two types of hearing loss
Conduction deafness
Nerve deafness
What causes conduction deafness
Problems with the mechanical system that transmits sound waves to the cochlea
What type of deafness can be helped with hearing aids
Conduction deafness
What causes nerve deafness
Damaged receptors within the inner ear or damage to the auditory nerve itself
What do sensory prosthetics do
Provide sensory input that can, to some extent, substitute for what cannot be supplied by the persons sensory receptors
What is an example of a sensory prosthetic
Cochlear implants
What is bottom up processing
The system takes in individual elements of the stimulus and then combines them into a unified perception
What is top down processing
Sensory information is interpreted in light of existing knowledge, concepts, ideas and experiences
What did the gestalt movement set out to do
Discover how we organise the parts of the perceptual field into a unified and meaningful whole
What is the goal of perception
To recognise objects in the environment according to organisation of their elements
What does the gestalt principle argue
The whole is more than and different to the sum of its parts
What is figure down relations
Our tendency to organise stimuli into a central or foreground figure and a background
What is the law of similarity
Similar elements will be perceived as belonging together
What is the law of proximity
Elements that are near each other are likely to be perceived as part of the same configuration
What is the law of closure
People tend to fill in gaps n incomplete figures
What is the law of continuity
People link individual elements together to form a pattern that makes sense
What is a perceptual scheme
A mental representation or image containing the critical and distinctive features of a person, object, event or other perceptual phenomenon
What is a perceptual set
A readiness to perceive stimuli in a particular way
What is the purpose of perceptual constancies
They allow us to recognise familiar stimuli under varying conditions
What is the purpose of shape constancy
Allows us to recognise people and other objects from many different angles
What is brightness constancy
Relative brightness of objects remain the same under different conditions of illumination
What is size constancy
The size of objects remain relatively constant even though images on our retina change in size with variations in distance
What are the two types of cues
Monocular
Binocular
What are monocular depth cues
Cues that require only one eye
What is linear perspective
The perception that parallel lines converge in the distance
What is texture/clarity
Clear objects are judged to be closer
What is interposition
Objects closer to us may cut off parts of our view of more distant objects
What is relative size
With objects of similar size, the one that looks smaller is judged to be farther away
What is the motion paradox
If we are moving, nearby objects appear to move faster than faraway ones
What are binocular depth cues
Cues that require both eyes
What is binocular disparity
Each eye sees a slightly different image
What produces convergence
Feedback from the muscles that turn your eyes inward to view a close object
What are illusions
Compelling but incorrect perceptions
What is the main cause of illusions
Perceptual constancies
