Sensation and Perception Flashcards
Differentiate between sensation and perception
Sensation is feeling( transfusing) while perception is interpretation ( processing) of the feeling
Name some type of receptors
- Photoreceptors
- Hair cells
- Nociceptors( pain/ noxious stimuli)
- Thermoreceptors
- Osmoreceptors
- olfactory receptors
- taste receptors
- Propioception=position
- mechanoception
Signal detection theory
focuses on changes in perception of the same stimuli due to presence of internal and external factors
What are catch trials/noise trials in SDT
catch trials have the actual signal presented, noise trials have no stimuli
What are possible outcomes for SDT
- Miss/Hit
- if signal is + and “yes”= hit
- if signal + and “no”= miss
- if signal - and “yes”= false alarm
- if signal - and “no”= correct rejection/negative
What is adaptation
decrease in response to a stimuli over time e.g. pupils dilate ( in low light) and constrict in high light. Ear drum contracts in loud music, cold water no longer gets cold once used to it
What is the pathway for a stimulus to reach conscious perception
sensory receptor- afferent neuron-sensory ganglion-spinal cord-brain
How does adaptation affect a difference threshold
As adaptation kicks in, the difference in threshold to evoke a response must be larger. i.e you get used to the small fluctuations hence you need a large change to feel any difference
Structure and function of the eye
- Cornea- front part, gathers light
- Pupil- opening
- Ciliary body-produce aqueous humor
- Lens-refracts light to aim it at retina
- Canal of schlemm- drains aqueous humor
- Retina- contains rods/cones that transduce light
- Sclera- structural protection around eye
- Ciliary muscle-contracts under parasympathetic control to constrict pupil
- Suspensory ligaments holds onto the lens and controlled by ciliary muscle
Duplicity theory of vision
posits that the retina contains 2 kinds of photoreceptors
Describe make up of the retina
- Made up of 6m cones and 120m rods
- Cones for colour vision and fine details( in bright light, 3 isoforms)
- Rods for low light (rhodopsin)
What is the central section of the retina? what does it contain. where is vision best/ blindspot
- Central retina part= macula ( mostly cones)
- macula contains fovea- only cones and has best visual acuity
- Blind spot occurs at the optic disc- no receptors there
What is the lateral geniculate nucleus LGN
part of the thalamus involved in light processing
What is parallel processing
- the ability to simultaneously analyse shape, color and motion
*parvocellular cells have high colour spatial resolution for shape
*magnocellular cells detect motion have high temporal resolution
- What are the ossicles
- Cochlea
- Vestibule
- semi-circular canals
- Ossicles structures within middle ear (stapes,malleus, incus)
- spiral shaped organ in inner ear has organ of corti( has endolymph and hair cells) that links to vestibulocochlear nerve
- Consist of utricle and saccule( have modified hair cells= otoliths)- used for balance- propioception (lateral acceleration)
- 3 perpendicular arranged structures with ampulla with hair cells- detect rotational acceleration
What does the medial geniculate nucleus do
MGN is the part of the thalamus that processes sound stimuli and directs it to temporal lobes
What does the the Place theory purport?
states that the location of the hair cell on the basilar membrane determines the perception of pitch when hair cell is vibrated i.e. high pitch cause hair cells close to the oval window vibrate while low pitch cause hair cells away from oval window(apex) to vibrate
What structures are used to detect linear and rotational acceleration.
Linear acceleration- utricle and saccule, rotational- semicircular canals
How does the organization of cochlea indicate the pitch of an incoming sound?
the cochlea is tonotopically organised such that the basilar membrane has hair cells at the base vibrate for high pitch sounds and those at the apex for low pitch sounds
What is somatosensation?
Sensing in terms of touch, temp, vibration, pain,pressure
Name and provide function of the 5 somatosensory receptors
- Pacinian corpuscles-deep pressure and vibration
- Meissner corpuscles- light touch
- Merkel cells(discs)- deep pressure and texture
- Ruffini endings- stretch
- Free nerve endings- pain and temperature
What is two point thresholds, physiological zero, gate theory of pain.
- Two point thresholds is the minimum distance necessary bwtn 2 points that can be felt as separate
- Physiological zero is the temperature of an object relative to normal body temp. If lower that NBT then cold, if higher then warm
- Gate theory of pain- pain is a fxn of small nerve(nociceptive) fibers and large nerve(nonnociceptive) fibers. The two compete to either open the “gate” and one feels pain or close them to impede pain perception. eg rubbing after knocking ur ankle on the desk, massage and touch all reduce gate opening since they’re engaging the large nerve fibers and hence block the pain signal
Differentiate between bottom up and top down processing
- Bottom up is recognition of objects by parallel processing and feature detection( data driven). Slow but less prone to mistakes
- Top-down(conceptually driven) is recognition of an object by comparing to memories and expectations with little attention to detail. it is quick and prone to errors
Perceptual organisation refers to
synthesis of all stimuli to make sense of the world around us in terms of form, depth(stereopsis), motion, constancy
- Depth perception relies on?
- Form of an object relies on?
- Motion is determined by?
- Both monocular and binocular cues
- Parallel processing and feature detection
- Magnocellular cells
What are monocular visual cues
these rely on one eye
- Relative size- closer ant is bigger than one away
- Interposition(superposition)-objects that move in front of other objects must be closer
- Lighting and shading/ contouring
- Relative height- taller things are further away
- Motion parallax- things closer move faster than those away
What are the two binocular cues
- Retinal disparity (about 2.5in apart)
- Convergence- things far away eyes are relaxed, those close, contract and turn inwards
What is constancy?
We perceive that xtics of something doesnt change despite change in envronment eg size, colour, shape or brightness
What are Gestalt principles
the way the brain formulates missing parts of a stimuli to complete a picture
- Law of proximity- things close together grouped together
- Law of similarity-similar objects grouped together
- Law of good continuation-elements appearing to follow a path are grouped together
- Subjective contours-seeing shapes that are not really there
