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122 Cards in this Set
- Front
- Back
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describe the pathway of the visual system |
not a single pathway, multiple specialised to extract different aspects of a scene dorsal pathway ventral system |
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what is the dorsal pathway? |
- dorsal pathway: linked to processing information about where an object is, |
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what is the ventral system? |
- ventral system: linked to determining what the object is, |
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what region of the brain fully processes a (visual) attribute? |
- no single region of brain fully processes a particular attribute, - can never be totally blind to single aspect of perception (such as motion or colour), - e.g. motion is processed at different stages in dorsal & ventral pathways, |
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what does the 'binding problem' ask? |
- ‘binding problem’ - mystery of cognitive neuroscience, - asks how we bind all the sensory components into one complete perceptual whole, - e.g. holding a rose: coloured petals, velvet texture, pleasant aroma fuse to form percept, |
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what is sensation? describe the process of sending this info to the brain |
Sensation - stimulus detection process by which sense organs respond to & translate environmental stimuli, - from stimulus to sensory receptor to neural representation (nerve impulse) to brain, |
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what is perception? |
Perception - making ‘sense’ of what our senses tell us, process of organising stimuli & giving them meaning |
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what is transduction? |
- transduction: process whereby characteristics of a stimulus are converted into nerve impulses, |
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what are the 5 classical senses and what can they also provide information about? |
- vision, audition (hearing), gustation (taste), olfaction (smell) and touch, - additionally, senses provide info re: balance, body position, pressure, pain, temperature, |
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what does psychophysics study and what 2 kinds of sensitivity is it concerned with? |
- psychophysics: studies relations between physical characteristics of stimuli & sensory capability, - concerned with two kinds of sensitivity… 1. absolute limits (e.g. dimmest light, faintest sound, weakest taste we can detect), 2. differences btw stimuli (e.g. what is smallest difference btw tones we can detect), |
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what is the absolute threshold and what does lower absolute threshold mean? |
- lowest intensity at which a stimulus can be detected 50% of the time, - lower absolute thresholds mean greater sensitivity… - e.g. hearing = tick of watch under quiet conditions from 6m away, - taste = 1tsp of sugar in 7.5L of water, - vision = candle flame seen at 50km distance on a clear, dark night, |
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what are decision criterion and what does it vary based on? |
decision criterion: standard we decide for certainty of stimulus before we report detection, - varies based on circumstances, experiences, time of day etc. |
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what is signal-detection theory concerned with? |
- signal-detection theory: concerned with the factors that influence sensory judgements, |
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what are subliminal stimuli? |
- subliminal stimuli: very weak stimuli that do not register in awareness, can influence behaviour, |
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what is the just noticeable difference and what are some examples of where it can be seen/is applied? |
- defined as smallest difference between two stimuli that people can perceive 50% of the time, - slight variation in taste might signal food is spoiled, slight shade of paint difference is perceptible, - tuning musical instruments, performing surgery, etc. all require ability to discriminate subtleties, |
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what is Weber's Law and what is an example? |
- Weber’s law: j.n.d. directly proportional to magnitude of stimulus with which comparison is made, - e.g. j.n.d. value for weights is a Weber fraction of approx. 1/50, - if you lift weight of 50 grams, a comparison weight must be 1/50th (1g) heavier / lighter, - if you lift weight of 500 grams, a comparison weight must be 1/50th (10g) heavier / lighter, |
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what is sensory adaption? |
- diminishing sensitivity to an unchanging stimulus (i.e. habituation), |
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where does sensory adaption occur and describe research done on it |
- occurs in all sensory modalities, - RM Pritchard (1961) attached tiny projectors to contact lenses of participants, - procedure guaranteed visual images would maintain constant position on retina, - participants reported images approved in entirety then began to vanish & reappear, |
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what is the stimulus for vision and what is it measured in? |
- stimulus for vision is electromagnetic energy (light waves) which are measured in nanometres |
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what wavelengths are humans only sensitive to? |
- human visual system is only sensitive to wavelengths extending from 700~400 nm (red to blue), |
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where do lightwaves enter the eye and what is this structure? |
- light waves enter eye through the cornea, transparent protective structure at front of eye, |
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what is the structure behind the cornea? |
behind cornea is pupil, an adjustable opening that can dilates to control amount of light entry, |
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what is the pupil's size controlled by and what causes the pupil to dilate? |
- pupils’ size is controlled by muscles in the coloured iris that surrounds the pupil, - low levels of illumination cause pupil to dilate - lets more light in to improve clarity |
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what is behind the pupil? |
- behind pupil is lens, elastic structure becomes thinner for distant & thicker for nearby objects, |
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what does the lens of the eye focus the visual image on? |
- lens of the eye focuses the visual image on the retina, multilayered light-sensitive tissue at rear, |
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what is myopia and what does it result from? |
- short-sightedness (myopia) results from lens malfunction, difficulty seeing far away objects |
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what is hyperopia and what does it result from? |
- long-sightedness (hyperopia) results from lens malfunction, difficulty seeing near objects, |
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what does the retina contain? |
- retina is extension of brain, containing two types of light sensitive receptor cells (photoreceptors) - rods and cones |
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what do rods do? |
rods: function in very dim light levels, being about 500 times more sensitive than cones, - unable to generate a percept of colour, used at night in monochromatic sense, |
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what do cones do? |
- cones: function best in bright light levels, multiple types generate percept of colour, |
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where are rods found? |
- rods are found throughout entire retina except in the fovea (small area at centre of retina), |
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what is the fovea |
small area at centre of retina - contains no rods, densely packed cones, which decrease away from the centre, |
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what does the periphery of the retina contain? |
- periphery of the retina contains mainly rods, |
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how to rods and cones send messages to the brain? |
- rods & cones send messages to brain via two additional layers of cells, bipolar & ganglion cells |
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what do bipolar cells do? |
- bipolar cells: facilitate synaptic connections |
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what do ganglion cells do? |
- ganglion cells: axons are collected into a bundle to form the optic nerve, |
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how do rods and cones fire signals? |
- typically many rods are connected to same bipolar cell, additive effect fires signal, - cones are individually strong enough to fire signal, operate singularly, |
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what is visual acuity? |
- visual acuity: ability to see fine detail, |
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what is the blind spot? |
- blind spot: area of vision that is inhibited by optic nerve (axons of the ganglion cells) exit to brain, - near fovea, results in an area where there are no photoreceptors, |
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what are photopigments? |
- photopigments: protein molecules translate light waves from photoreceptors to nerve impulses, |
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describe the process of how photopigments translate light waves from photoreceptors to nerve impulses |
- absorption of light by the photopigments produces a chemical reaction, - changes rate of neurotransmitter release at the receptor’s synapse with the bipolar cells, - greater change passes stronger signal to bipolar cells then to ganglion cells (optic nerve), - stimuli trigger nerve responses at each level (rod or cone, bipolar and ganglion cell), - results in instantaneous message carriage to visual relay station (thalamus), - onwards to visual cortex in brain to form perceptions, |
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what is dark adaption? |
- progressive improvement in brightness sensitivity over time under conditions of low illumination, |
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describe the process of dark adaption and what happens after an hour of it |
- after absorbing light, photoreceptor is depleted of pigment molecules for period of time, - photopigment molecules regenerate during dark adaptation and sensitivity increases greatly, - after an hour of dark adaptation, can detect light intensities 1/10 000 great as those prior |
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in colour vision, how much variation in hues can we see? |
- we can distinguish an estimated 7.5m hue variations, |
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what does Helmholt's trichromatic theory state and what are some flaws in it? |
- Helmholtz’s trichromatic theory: there are three types of colour receptors in the retina, - individual cones are sensitive to wavelengths that correspond to either blue, green or red, - ultimately comprises all colours in some combination, - red + green = yellow, yet people with red & green colour blindness are able to see yellow, - also flawed by presence of ‘afterimage’ in contrasting hues after prolonged exposure, |
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What does Hering's opponent-process theory state and what does it explain? |
- Hering’s opponent-process theory: each of the 3x cone types respond to 2 different wavelengths, - one type responds to blue or yellow, another to red or green and a third to black or white, - explains after-image and relationship between opposing hues, |
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what does the dual-process theory state? |
- dual-process theory: it’s modernly understood that both theories (Helmholt's trichromatic theory and Hering's opponent-process theory) are valid for colour transduction |
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what are trichomats? |
- trichromats: people with normal colour vision (sensitive to all three systems), |
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what percentage of people have deficiencies in a (visual) system and what is this usually caused by? |
- 7% of males, 1% of females have deficiencies in at least one system, - caused by absence of hue-sensitive photopigment in certain cone types |
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what is a dichromat? |
- dichromat: only colour blind to one system, |
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what is a monochromat? |
- monochromat: sensitive only to the black-white system and is totally colour blind, |
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where does step one in the perception of stimuli occur and what does it involve? |
Step One in Perception of Stimuli - occurs in the Primary Visual Cortex (i.e. V1) - first area of cortical processing, - involves the coding of lines and edges which comprise the distinctive features of visual scenes, - V1 neurons are receptive to stimulus width, length, motion direction & speed, - neurons are activated in unique combinations to reconstruct visual info (not 1:1 ratio), |
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what are the stimuli for our sense of hearing? |
- stimuli for our sense of hearing are sound waves, a form of mechanical energy |
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what is sound? |
- sound: pressure waves in air, water or some other conducting medium, - resulting vibrations cause successive waves of compression & expansion, - waves have frequency & amplitude… |
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what is frequency, how is it measured and how is it related to pitch? |
- frequency: number of sound waves, or cycles, per second, - the hertz (Hz) is the technical measure of cycles per second, 1 hertz = 1 cycle per sec, - sound wave frequency is related to perceived pitch, higher frequency = higher pitch, |
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what is amplitude, what does it determine and what is the absolute threshold for hearing? |
- amplitude: refers to the vertical size of the sound waves, - amount of compression & expansion of the molecules in the conducting medium, - determines loudness (decibels - dB), absolute threshold for hearing = 0 decibels, |
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what is the transduction system made out of and what is their job? |
- transduction system is made up of tiny bones, membranes and liquid-filled tubes, - designated to the translation of pressure waves into comprehensible nerve impulses |
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what is the cochlea and what does it contain? |
- cochlea: coiled tube that is filled with fluid, contains basilar membrane, |
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what is the organ of Corti? |
- organ of Corti: atop basilar membrane, tiny hair cells that are sound receptors, |
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describe the process of auditory transduction |
- hair cells (organ of Corty) synapse with neurons of auditory nerve send impulses via auditory relay station, - when sound waves strike the eardrum, pressure sets fluid inside cochlea into motion, - fluid waves that result vibrate the basilar membrane, causing a bending of the hair cells, - bending of hair cells triggers release of neurotransmitters into synaptic space, - nerve impulses are then sent to brain - auditory cortex has neurons to respond to different types, |
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what does the auditory system do? |
- auditory system transforms sensory qualities of wave amplitude & frequency into nerve impulses, |
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what do high-amplitude sound waves cause and what does this result in? |
- high-amplitude sound waves cause the hair cells to bend more, - in turn, more neurotransmitter released at point of synapse with auditory nerve cells, - results in higher rate of firing within the auditory nerve, |
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what are the two processes for coding frequency to hear pitches? |
frequency theory and place theory |
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explain the frequency theory and a flaw of it
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- frequency theory: nerve impulses sent to brain match frequency of sound wave, - flawed by limited rates of neuron firing (cannot produce high enough frequencies), - likely valid for low frequency pitch (below 1000Hz), |
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explain place theory |
- place theory: specific point in cochlea where fluid wave peaks serves as frequency coding cue, - likely valid for high frequency pitch (1000 - 4000Hz), |
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what is sound localisation and how is this achieved? |
Sound Localisation - ability to locate objects that emit sounds, - nervous system uses info re: time & intensity differences of sounds arriving at both ears, |
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what are the 2 major types of hearing loss than affect 1 in 6 adults? |
conduction deafness nerve deafness |
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what is conduction deafness? |
- conduction deafness: problems with mechanical system that transmits sound waves to cochlea |
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what is nerve deafness? |
- nerve deafness: damaged receptors within inner ear or damage to auditory nerve itself, |
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what are taste buds and what is each bud most responsive to? |
- taste buds: chemical receptors concentrated along tip, edges & back surface of the tongue, - each bud is most responsive to one or two basic taste qualities, |
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what increases the intensity of other taste sensations and what is this activated by? |
- additional taste sensation (umami) increases intensity of other taste qualities, - umami is activated by proteins and monosodium glutamate (MSG), |
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what other sense is olfaction intertwined with? |
- works collectively with gustation to perform similar function, thoroughly intertwined senses |
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what are smell receptors? |
- smell receptors: long cells that project through upper nasal cavity lining into mucous membrane, |
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describe the predominant theory on smell discrimination |
- olfactory receptors recognise diverse odours individually, rather than mixing activity, - receptors fire & send input to the olfactory bulb, forebrain structure above nasal cavity, |
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what are pheromones? |
- pheromones: chemical signals found in natural body scent, may affect behaviours subtly, |
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what is menstrual synchrony and what do studies suggest is the reason for this? |
- menstrual synchrony: tendency of women living together to have synchronised cycles, - studies suggests pheromones can synchronise menstruation cycles, |
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how do odours influence attraction? |
- attraction: odours are speculated to make us sexually attractive to others, not studied, |
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what do tactile senses enable us to do? |
- enables us to escape danger, alerts bodily disorders, injuries & pleasures (e.g. sexual orgasm), |
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what influence does touch have on babies development? |
- touch enhances newborn babies’ development, lack can retard development, |
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what is skin and what does it contain? |
- skin: multilayered elastic structure, covers 1.7sqm, weights 2.7-4.5kg, largest organ in body, - contains a variety of receptor structures, unclear how they specify |
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what are free nerve endings? |
- free nerve endings: simple nerve cells beneath skin surface in tree-like structures, - primary receptors for pain and temperature, |
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what are basket cell fibres? |
- basket cell fibres: situated at base of hair follicles, receptors for touch & light pressure, |
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why/how does the brain locate sensations? |
- brain locates sensations because skin receptors send messages to somatosensory cortex, - sent to corresponding area to nerve cell position on body |
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what is the phantom limb phenomenon and what is it an example of? |
- phantom limb phenomenon: amputees experience vivid sensation from missing limb, - example of how the brain can ‘locate’ sensations that cannot possibly be present, - tends to disappear upon utilisation of a prosthetic limb, |
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describe the process of processing/recognising pain |
- free nerve endings in skin & organs respond to mechanical, thermal & chemical stimulation, - send nerve impulses into spinal cord, sensory tracts carry pain info to the brain, - sensory info re: pain intensity & location is relayed by thalamus to somatosensory cortex, - brain processing of pain occurs faster than other kinds of tactile stimuli (rapid response), |
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what does the gate control theory (of pain) theorise? explain how this works |
Gate Control Theory - theorises that pain results from the opening & closing of gating mechanisms in nervous system, - events in spinal cord open system of spinal cord ‘gates’ allowing impulses to travel to brain, - other sensory input can purportedly close the gates and blunt our experience of pain, - e.g. scratching an itch / acupuncture stimulates tactile receptors & closes gates… |
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what does recent recent show in relation to glial cells and pain? |
- recent research shows glial cells are involved in creation of pathological pain, - activated by immune challenges (viral or bacterial) and substances released by neurons, - cytokines: messenger molecules are released to amplify pain & promote inflammation, |
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what are cytokines? |
cytokines: messenger molecules are released to amplify pain & promote inflammation, |
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what are opiates and how do they produce their effects? |
Opiates - psychoactive compounds (e.g. morphine, heroin) that relieve pain & affect pleasure system, - produce effects by locking into brains’ specific receptor sites associated with pain perception, |
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nervous system has its own natural analgesics (painkillers) with opiate-like properties. what does this explain and what is an example of one? |
- explains why there are receptor sites for opiates to bind themselves to, - endorphins: natural opiates (endogenous [internally produced] morphines), - endorphin surges upon contact with pain affect thalamus, amygdala, sensory cortex etc. |
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what does kinaesthesis do? |
- provide us with feedback about our muscles’ & joints’ positions and movements, |
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what are kinaesthetic receptors and what does information this sense gives us all for? |
- kinaesthetic receptors are nerve endings in the muscles, tendons & joints, - information this sense gives us allows for coordination of movements, |
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what is vestibular sense and when are vestibular receptors located? |
- vestibular sense: cooperates with kinasethesis to give sense of body orientation & equilibrium, - vestibular receptors are located in inner ear, |
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what is bottom-up processing? |
bottom-up processing: system takes in individual elements of stimuli, - then combines them to form a unified perception, occurs when we read, |
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what is top-down processing and what does it account for? |
- top-down processing: info is interpreted in light of existing knowledge, concepts, ideas etc. - occurring as you interpret the words and sentences constructed by bottom-up process, - accounts for psychological influences on perception such as the role of past experience, |
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what is attention? |
- attention: process of focusing on certain stimuli whilst filtering out other incoming information, |
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what is inattentional blindness? |
- inattentional blindness: refers to failure of unattended stimuli to register in consciousness, - e.g. we look right at something without ‘seeing’ it if we are attending to something else, |
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what are some stimuli characteristics that affect attention? |
stimuli characteristics affecting attention incl. intensity, novelty, movement, contrast & repetition, |
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what stimuli are people especially attentive to? |
- people are especially attentive to stimuli that have relevance to their wellbeing (survival value), |
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what are gestalt principles? |
- top-down process of perceptual organisation that groups, differentiates & organises visual info. the sum is greater than the individual parts |
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what is figure-ground? |
- figure-ground: tendency to organise stimuli into central (foreground) figure & background, - separating figure & ground can be ambiguous (two plausible perceptions) or obvious, |
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what are the laws of perceptual organisation? |
- laws of perceptual organisation: similarity, proximity, closure & continuity, |
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what is similarity? |
- similarity: when parts of are perceived as similar, they are perceived to belong together |
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what is proximity? |
- proximity: elements that are close together are perceived as part of same configuration, |
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what is closure? |
closure: we tend to close open edges of a figure / fill in gaps in incomplete figures, - so that identification of the form appears more complete than it actually is… |
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what is continuity? |
- continuity: we link individual elements together so they form a continuous line / pattern, |
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what are perceptual schemas and what do they do? |
- mental representations of images containing critical & distinctive features of phenomena, - provide mental templates that allow us to classify & identify sensory input from top-down, - e.g. friend greets you, appearance matches internal schemas, so they are recognised, |
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what is perceptual set/expectancy? |
- a readiness to perceive stimuli in a particular way, often based on what we expect to see, |
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what is perceptual constancy? |
- percepts are stable under changing viewing conditions, objects tend to remain the same, |
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what does the visual system do the size of images it receives? |
- visual system takes retinal-image size and scales by its estimate of distance to the object, - thus we know that object size doesn’t change based on our distance away from them, |
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describe perceptual constancy for shapes and colour |
- shape & colour constancies also exist, perceived brightness of objects remains same, - visual cells are sensitive to contrast in luminance between object & background, |
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describe how depth perception is achieved |
Depth Perception - retina receives info. in only two dimensions (length & width) but brain translates cues into 3D, - depth is perceived through combination of monocular (one eye) & binocular (both) depth cues |
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list and explain some monocular depth cues |
- monocular depth cues: judging relative distances of objects through one eye, - patterns of light & shadow: depth effect that is equally powerful with one eye as both, - linear perspective: perception that parallel lines converge as they recede into distance, - interposition: objects closer to us may cut off part of our view of more distant objects, - horizontal plane: conveys distance (e.g. ship higher up horizon v. ship near shore), - relative size: two objects we know to be similar size, smaller one is further away |
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list and explain so binocular depth cues |
- binocular depth cues: judging relative distances of objects using both eyes, - binocular disparity: each eye sees a slightly different image, - responses of depth-sensitive neurons to disparity integrate to perceive depth, - convergence: result of muscle feedback when turning eyes inward to view near objects, - e.g. finger moving towards you, messages sent to brain by eye muscles are depth cues, |
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what is motion? |
- motion is the change in location over time, brain contains cells that directly detect motion |
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what is the waterfall effect |
- ‘waterfall effect’: staring at motion of object, nearby, static objects appear to move oppositely |
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at what level is motion related information extracted? |
- motion related information is extracted at primary visual level (by the V1 neurons), |
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explain optic-flow information |
- optic-flow information: pattern of motion produced on retinae as we move through world, - radially expanding pattern indicated forward motion, contracting pattern = backwards, - circular pattern = circular motion & translational pattern = motion parallel to surface, |
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what are illusions and why do they occur? |
- compelling but incorrect perceptions (sensory & perceptual), - occur due to limitations made in the encoding of information, |
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what can most visual illusions to attributed to? |
- most visual illusions can be attributed to perceptual constancies that generally help us, - distance cues are manipulated and shortcuts result in mistaken visual perception, |
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what is the muller-lyer illusion useful for? explain what it is |
- Müller-Lyer illusion: useful for examining cross-cultural differences in perception, - line appears longer when V-shaped arrow ends radiate outward rather than inward, - Westerners are susceptible as a result of their exposure to rigid, geometric architecture, - ‘carpentered world’ opposed to ungroomed environments of other cultures = no effect, |
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what are critical periods? |
- time windows for certain experiences to occur within, for perceptual abilities to develop normally, - innate properties develop across early life span in ‘use it or lose it manner’, - e.g. kittens raised in room with only vertical lines couldn’t perceive outside world properly, |
