Perception and Sensation Flashcards
Accommodation of the lens
when you adjust the lens’ focus for objects at different distances
blind spot
The retinal area where the optic nerve exits
brightness contrast
It is the increase or decrease in an object’s apparent brightness by comparison to the objects around it
colour constancy
The tendency of an object to appear nearly the same colour under a variety of lighting conditions
cone
adapted for perceiving colour and detail in bright light
cornea
a rigid transparent structure on the surface of the eyeball, which refracts the incoming light to focus on the lens
dark adaptation
The gradual improvement in the ability to see in dim light
electromagnetic spectrum
the continuum of all frequencies of radiated energy
fovea
The central area of the human retina, and is adapted for detail vision
best for colour vision
it has the greatest proportion of cones relative to rods
ganglion cells
Ganglion cells are the projection neurons of the vertebrate retina, conveying information from other retinal neurons to the rest of the brain.
iris
The coloured structure on the surface of the eye surrounding the pupil
lens
a flexible structure that varies its thickness
negative afterimage
Experiences of one colour after the removal of another
opponent-process theory
We perceive colour in terms of paired opposites (red VS green, yellow VS blue)
optic nerve
The optic nerve is comprised of millions of nerve fibres that send visual messages to your brain to help you see
perception
it is the interpretation of that information
periphery
after prolonged adaptation to dim light, this sees best
it is the ability to see things out of your direct line of sight
pupil
An adjustable opening that widens and narrows to control the amount of light entering the eye
receptor
Specialised cells that convert environmental energies into signals for the nervous system
retina
A layer of visual receptors covering the back surface of the eyeball
retinex theory
The cerebral cortex compares the patterns of light coming from different parts of the retina and synthesises a colour perception for each area
rod
they are adapted for vision in dim light
sensation
It is the conversion of energy from the environment into a pattern of response by the nervous system
stimulus
energies from the world around us affect us in some way
trichromatic theory
Colour or vision depends on the relative responses of three types of cones: 1. Short-wavelength, medium-wavelength and long-wavelength
How does colour vision occur?
Colour vision depends on three types of cones, each sensitive to a particular range of light wavelengths. Cones transmit messages so that later cells in the visual system indicate one colour (e.g., blue) by an increase in activity and another colour (e.g., yellow) by a decrease. The cerebral cortex compares responses from different parts of the retina to determine colour experiences.
absolute sensory threshold
the intensity at which a given individual detects a stimulus 50% of the time
binocular cues
Retinal disparity and convergence are called binocular cues as they depend on both eyes
bottom-up process
in which tiny elements combine to produce larger items
closure
we imagine the rest of the figure when a familiar figure is interrupted
continuation
the filling in of the gaps when lines are interrupted
convergence of eyes
The degree to which they turn to focus on a close object
depth perception
It is the perception of distance, and it enables us to experience the world in 3D
feature detector
They are specialised neurons in the visual cortex and they respond to the presence of simple feature, such as line and angles
figure and ground
when you distinguish the object from the background
Gestalt psychology
A field that emphasises perception of overall patterns
Common fate: we perceive objects as part of the same group if they change or move in similar ways at the same time
good figure
a simple, familiar, symmetrical figure
induced movement
when you incorrectly perceive the object as moving
monocular cues
It enables you to judge depth and distance with just one eye, or when both eyes see the same image
moon illusion
The moon at the horizon appears about 30% larger that it appears when it is higher in the sky
motion parallax
It is the difference in speed of movement of images across the retina as you travel
optical illusion
it is the misinterpretation of a visual stimulus
proximity
it is the tendency to perceive objects that are close together as belonging to a group
retinal disparity
It is the difference in the apparent position of an object as seen by the left and right retinas
reversible figure
it can be perceived in more than one way
signal-detection theory
It is the study of people’s tendencies to make hits, correct rejections, misses and false alarms
similarity
the tendency to perceive similar things as being a group
stroboscopic movement
An illusion of movement created by a rapid succession of stationary images
subliminal perception
It is the phenomenon that a stimulus can influence behaviour even when it is presented so faintly or briefly that the observer has no conscious perception of it
top-down process
where you apply your experience and expectations to interpret each item in context
visual constancy
Perception illustrates this and it is our tendency to perceive objects as keeping their shape, size and colour, despite distortions in the actual pattern reaching the retina
waterfall illusion
If you stare at a waterfall for a minute or more and then turn your eyes to nearby cliffs, the cliffs appear to flow upward
Detecting rare stimuli
when people are trying to detect some item, they are more likely to overlook it if it occurs rarely
perception of minimal stimuli
No sharp dividing line distinguishes sensory stimuli that can be perceived and sensory stimuli that cannot be perceived
capsaicin
it is a chemical that stimulate receptors that respond to painful heat
cochlea
it contains the receptors for hearing and it is a snail-shaped organ
conduction deafness
It results when the bones connected to the eardrum fail to transmit sound waves properly to the cochlea
cutaneous senses
It means skin senses, also known as the somatosensory system (body-sensory system)
endorphin
Are neurotransmitters that weaken pain sensations
frequency
The frequency of a sound wave is the number of cycles (vibrations) per second
frequency principle
At low frequencies (about 100hz), a sound wave through the fluid of the cochlea vibrates all the hair cells, which produce action potentials in synchrony with the sound waves
Gate theory
The idea that pain messages must pass through a gate, presumably in the spinal cord, that can block the messages
hertz
the unit for frequency
loudness
It is a perception of the intensity of sound waves
nerve deafness
Resulting from damage to the cochlea, hair cells, or auditory nerve
olfaction
the sense of smell
phantom limb
Continuing sensations, including pain, in a limb long after it has been amputated
pitch
It is a perception closely related to frequency
Place Principle
The highest frequency sounds vibrate hair cells near the stirrup end, and lower frequency sounds (about 100-200hz) vibrate hair cells at points farther along the membrane
sound waves
vibrations of the air, water, or other medium
synesthesia
A condition in which a stimulus of one type, such as sound, also elicits another experience, such as colour
taste
it detects chemicals on the tongue
taste bud
Taste receptors, located in the folds on the surface of the tongue, mainly along the edge of the tongue in adults
timbre
tone complexity
vestibular sense
It detects the tilt and acceleration of the head, and the orientation of the head with respect to gravity
Volley Principle
Volleys of hair cells which responds to each vibration with an action potential
Localising sounds
We localise a sound source by detecting differences in the time and loudness of the sounds in the two ears. We localise the distance of a sound source primarily by the amount of reverberation following the main sound
individual differences in sensation and perception
Some people have three times as many taste buds as others do, giving them greater sensitivity to taste. People vary in their genes for olfactory receptors, causing certain odours to seem stronger.
