UNIT 7: Sensation and perception Flashcards
transduction
The process of converting one form of energy into another that your brain can use
absolute threshold
minimum stimulation needed to detect a particular stimulus (light, sound, pressure, taste or odour) 50% of the time
‘just noticeable difference’
the minimum difference a person can detect between any two stimuli half of the time
Weber’s Law
principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage
Different thresholds
increase in proportion to the size of the stimulus. When stimulation is unchanging, you become less sensitive to the stimulus
sensation adaptation
diminished sensitivity as a consequence of constant stimulation. When we are constantly exposed to a stimulus that does not change, we become less aware of it because our nerve cells fire less frequently
sensation
the process by which our sensory receptors and nervous system receive and represent stimulus from our environment
Perception
the process of organising and interpreting sensory information, enabling us to recognise meaningful objects and events.
Bottom up processing
analysis that begins with the sensory receptors and works up to the level of the brain
- relies on sensation over perception
Top down processing
information processing is guided by higher-level mental processes, as we construct perceptions, drawing on our experience and expectations
-prone to bias (jumping to conclusion)
- occurs when you use prexisting knowledge
-perception over sensation
‘selective attention’
focusing intently on one task
inattentional blindness
when we become unaware of other visual stimulus around us
change blindness
failing to notice changes in the environment
-EX: when we are watching a magician’s left hand we fail to notice him changing cards with his right.
VISUAL
cocktail party effect
Think about trying to listen to your friend talking in the lunch queue - do you hear other people’s conversations, are you aware of everything else around you. Probably not because you are concentrating on one thing
AUDITORY
Wavelengths
the distance from the peak of one light or sound, to the peak of the next.
Lens
the transparent structure behind the pupil that changes shape to help focus images on the retina
Retina
light sensitive inner surface of the eye, containing the photoreceptor rods and cones plus layers of neurons that begin the processing of visual information
Fovea
the central focal point in the retina, around which the eyes cones cluster
Optic (visual) Nerve
the nerve that carries neural impulses from the eye to the brain
Blind spot
the point at which the optic nerve leaves the eye, creating a blind spot because no receptor cells are located there
Cornea
protects the eye and bends light to provide focus
Rods
retinal receptors that detect black, white and gray. They are necessary for peripheral and dim-light vision. Rods share bipolar cells: sending combined messages
Cones
retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Cones detect fine detail and enable you to perceive colour. In dim-light they become ineffectual
transmits to a single bipolar cell that relays the cone’s individual message to the visual cortex
Near sighted
too much curvature (via accommodation) of the lens focuses the image in front of the retina so nearby objects are seen more clearly than distant objects
Far sighted
too little curvature of the lens (via accommodation) focuses the image behind the retina so distant objects are seen more clearly than nearby ones
Young-Helmholtz trichromatic (3-colour theory)’.
the retina contains 3 different colour receptors (cones), each one especially sensitive to 1 of the 3 colours
When we stimulate combinations of these cones, we see other colours
Colorblind
lack a functioning red or green, or both sensitive cones
Monochromatic (one-colour)
Only 1 color
Dichromatic (two-colour)
2 colors
opponent-process theory.
the way humans perceive colors is controlled by three opposing systems
Rather than interpreting information from each type of cone in an individual manner, our visual system records differences in the responses of cones.
Afterimages
sense experiences that occur after a visual stimulus has been removed
come from looking at one color for a long period, which causes those receptor cells to become fatigued
Prosopagnosia (Face Blindness)
damage leads to an interruption of different aspects of the face-recognition process. The person has difficulty or cannot recognise other peoples faces, and even their own
Caused by damage to the occipital lobe
Blindsight
visual information from the eye is being processed unconsciously, so people with blindsight don’t know that they are visually processing.
Gestalt psychologist
our brain organises various visual stimulus into one meaningful ‘whole’.
Figure and ground process
The organisation of the visual field into objects (the figures) that stand out from their surroundings (ground). Visual stimulus is always organised into a figure, against the ground.
proximity
we group nearby stimulus together.
closure
we fill in gaps to create a whole object
similarity
we group similar figures together
visual cliff experiment
-shows us that depth perception is, to come degree, innate.
-The ability to convert the 2D images that strike our retina, into 3D, in order to judge distance
depth perception
the ability to judge the distance of objects. You interpret visual cues that tell you how near or far away objects are. Cues can either be binocular or monocular
Binocular cues
-These are depth cues which depend on BOTH eyes
-Our eyes are in different positions, so each receives a different image. The brain compares these images received from both eyes, to help judge distance
Monocular cues
-Clues about distance based on the image of ONE eye
Retinal disparity (BINOCULAR)
-Your eyes have slightly different views of the same object, because your eyes are positioned a few centimeters apart
-The greater the difference between the image from your left and right eye: the closer the object is
-The further away an object it, the more similar the images are from both eyes
Convergence
-inward turning of your eyes that occurs when you look at an object that is close to you
- you experience convergence when you look at the tip of your nose with BOTH eyes
Interposition (MONOCULAR)
(aka ‘overlap’) can be seen when a closer object cuts off the view of part or all of a more distant one
Relative size (MONOCULAR)
familiar objects provides a cue to their distance when the closer of two same-size objects casts a larger image on your retina than the farther one
Relative clarity (MONOCULAR)
can be seen when closer objects appear sharper than more distant, hazy objects
Texture gradient (MONOCULAR)
provides a cue to distance when closer objects have a coarser, more distinct texture than far away objects that appear more densely packed or smooth
Linear perspective (MONOCULAR)
provides a cue to distance when parallel lines, such as edges of sidewalks, seem to converge in the distance
Amplitude
How loud a sound is
Frequency
length of a sound wave determines the pitch
Eardrum
sound waves enter the eardrum and cause it to vibrate
Middle ear
tiny bones pick up the vibrations of the eardrum and send them to the cochlea, which is located in the inner part of the ear
Cochlea
-inner part of the ear
-The vibrations cause the cochlea to vibrate, which in turn, disrupts the fluid inside of it
basilar membrane
-The vibrations cause the cochlea to vibrate, which in turn, disrupts the fluid inside of it. The fluid movements cause ripples in the basilar membrane, which bend the hair cells which lie inside of it
auditory nerve
The hair cell movements trigger nerve impulses which are sent down the auditory nerve to the auditory cortex in the brain (located in the temporal lobe)
Place theory
we hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane. The brain determines a sound’s pitch by recognising the specific place on the membrane that generated the neural signal.
Frequency theory
the brain deciphers the frequency of the neural impulses travelling up the auditory nerve to the brain. The rate of nerve impulses travelling, matches the frequency of a tone, thus enabling us to understand pitch
it cannot explain how we can still hear very high pitched sounds, such as the upper third of a piano. This pitch would require a nerve impulse rate of higher than 1000 waves per second - which does not exist. It is not possible, yet we still hear it
Volley theory
This theory suggests that clusters of neurons take turns firing in sequence of rhythmic volleys - the number of volleys determines pitch
Sensorineural (known as ‘nerve deafness’)
hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerves
conduction deafness
hearing loss caused by damage to the middle ear system, such as the eardrum, that conducts sound waves to the cochlea. People with conduction deafness can hear vibrations when they reach the cochlea by ways other than through the middle ear
Olfactory receptor
The air we breathe in, reaches the olfactory receptor cells located at the top of the nasal cavity
Smell is the only sense that is NOT processed first in the thalamus of the brain.
Pheromones
chemical messengers that are secreted from other mammals. The most common known are sex pheromones which signal mating behaviours.
Gustation
sense of taste
taste buds/ taste receptors
inside each bump on your tongue there are over 200+ taste buds
temporal lobe
receives information from the taste buds and processes it so you recognise the taste and can attribute it to something i.e. we all know what an apple tastes like
Supertasters
more taste buds than the average person= can experience more intense taste
medium tasters
average ability to taste
nontasters
lower than average tasters
kinesthesia
your sense of the position and movement of your body parts
Vision plays a key role in helping your kinesthesia - you can look at where your are positioning your limbs and this helps direct movement
vestibular system
which stems from balance systems in the ears, also help maintain position and balance
semicircular canals
Any movement changes the fluids within small structures called the semicircular canals, found in the inner part of the ear
cerebellum
the ‘little brain’ responsible for movement and balance which helps us sense our bodily position and maintain balance
skin receptors
Touch is another sensory input, and some parts of our bodies are more sensitive to pressure, warmth, cold and pain
Gate control theory
the theory that the spinal cord contains a neurological ‘gate’ that blocks pain signals or allows them to pass to the brain
The ‘gate’ is opened by the activity of pain signals travelling up small nerve fibers.
The ‘gate’ is closed by activity in larger fibers, or by information coming from the brain.
endorphins
The brain can close the ‘gate’ and flood the body with endorphins to reduce or even completely eradicate pain sensation for a short duration
Phantom limb sensation
The brain can often misinterpret signals, as it makes the mistake that we are always fully functioning
This is why, those who have lost limbs, will often continue to ‘feel’ it and are compelled to use it during normal day to day life
This is evidence that it is not entirely about the stimulus input, but it is our mind that let us experience senses
sensory interaction
the principle that one sense may influence another. For example, how the smell of food influencing its taste
