Procssing The Environment Flashcards
Sensory perception I
We have binoculars vision which gives us retinal disparity and convergence (when object is far, eye muscles are relaxed and vice versa). These give depth cues. There are also monocular cues and size, shape and colour constancy cues
Just noticeable difference (JND): the threshold at which you begin to notice a slight difference in a sensation
Webber’s law states that the ratio of the background intensity to the incremental threshold is relatively constant for each person. The background intensity and incremental threshold are proportional.
Absolute threshold of sensation: minimum intensity of sensation required to perceive that sensation 50% of the time. Subliminal messages are below this threshold
Temperature = thermoception
Pressure = mechanoception
Pain = nocioception
Position = proprioception
Nonadapting neurons don’t change their firing rate. The slow adapting neurons fire fast at first and then slow down. The fast adapting neurons fire very fast when the stimulus starts then slows down, then stops when the stimulus stops.
Sensory perception II
The vestibular system helps with our sense of balance and spacial orientation. The cochlea is filled with specialised auditory receptors that send signals to the brain. The semicircular canals are orthogonal to each other and filled with a liquid that shifts when we move to sense which plane our head is moving in. Otolithic organs help us detect linear acceleration and head positioning.
Signal detection theory is about decision making with uncertainty. At what point is a signal strong enough that we notice it?
d’ is the strength of a signal and c is strategy (conservative, liberal). When c=0, this is the ideal observer. If >1, conservative (say no often) and if <1, liberal (say yes often)
Bottom up processing is when the stimulus influences our perception. It is data driven. Top down processing uses background knowledge to influence perception. Theory driven
Gestalts principles:
- similarity: items that are similar to each other are grouped together
- pragnanz: reality is often reduced to the simplest form
- proximity: objects that are close are grouped together
-continuity: lines are seen as following the smoothest path
- closure: objects grouped together are seen as a whole
Sight I
Sclera: white part; protects the eye and attachment site for muscles
Cornea: protects front of eye and bends light a little; is protected from friction and dust by the conjunctiva
Aqueous humour: in the cornea; water and salt that fills anterior chamber
Lens: biconvex; bends light more and becomes thinner or thicker by ciliary bodies (suspensory ligaments + ciliary muscle) depending on whether object is near or far
Iris: coloured part; 2 muscles that expand and contract changing the size of the hole
Pupil: the hole controlled by the iris; hole becomes bigger if it’s dark and vice versa
Vitreous humour: posterior chamber; water + salt + albumin; suspends the lens in place and gives structure
Retina: coats the back of the eyeball; has photoreceptors that convert light to a signal the brain can understand; has a dimple called the fovea with cones within the macula that lets us see in high levels of detail
Optic nerve: fibres from the retina that go to the brain to process signals from light
Choroid: network of blood vessels in the retina that nourish the retinal cells; black pigment
Sight II
Rods - really sensitive to light and good for night vision; a lot in the periphery; slow recovery time
Cones - a lot less than rods, give us colour vision; red (60%), green (30%) and blue (10%) - trichromatic theory of colour vision; centred in the fovea; help us see fine details; concentrated near the fovea; fast recovery time
Light comes in through the pupil and hits the retina.
Phototransduction cascade: When light hits the rod, it turns it off. Rods are made of rhodopsin with retinal molecules. Some of the light hits these molecules, changing them to a straight conformation, also changing the shape of the rhodopsin (in cones, photopsin). Transducin breaks away from rhodopsin and the alpha part binds to PDE. PDE takes cGMP and converts it from liquid to GMP. This causes sodium channels to close, the cell to hyper polarise and the rods turn off. This turns on the bipolar cell, activating a retinal ganglion cell which sends a signal to the optic nerve and then the brain
Optic nerves from both eyes converge at the optic chiasm. Signals from the right visual field go to the left side of the brain and vice versa
We use the parvo pathway to determine spatial resolution; boundaries and details of an object; but it has poor temporal resolution, so doesn’t work as well if the object is moving. For motion, we use the magno pathway. It has high temporal resolution and poor spacial resolution and doesn’t code for colour.
Parallel processing allows us to code for all these things at the same time
Types of vision
Photopic: high light levels
Mesopic: at dawn or dusk and involves both rods and cones
Scotopic: low levels of light
Sound
We need:
- a pressurised sound wave: air molecules become compressed creating areas of high and low pressure known as sound waves; lower frequency travels further
- hair cell
*the tensor tympani dampens loud sounds by tightening the tympanic membrane. This slows down transduction.
*auditory space is the area extending around the head in all directions that is used to perceive sound
Somatosensation
Adaptation is change over time in responsiveness of sensory receptors in response to a stimulus. It is downregulation. Amplification is upregulation of some stimulus in the environment.
The sensory strip in the cortex receives sensory input from everywhere. The somatosensory homunculus maps out the body in the brain.
Proprioception gives us our ability to sense position. It’s a cognitive awareness of your body in space. Kinaesthesia is more about the movement. It’s behavioural.
TrpV1 receptors have conformational changes due to temperature changes and pain. These break apart cells and their contents come back to the receptors and send signals through fibres. Fast fibres (A beta) have lots of myelin and bigger diameters which allow for quick signal transduction. medium fibres (A delta) have smaller diameters and less myelin so conduct signals slower. Slow fibres (C fibres) have really small diameters and have no myelin and so they send signals very slowly.
Ruffini - stretch
Merkel - sensing fine details
meissner- grip control
Pacinian - responds to vibration
Olfaction and Gustation
The cribiform plate separates the olfactory epithelium from the brain. The olfactory bulb sits on top of it and sends projections through it to the olfactory epithelium. A glomerulus is a destination point for various sensory olfactory cells that are sensitive to the same smell. This signal is sent to a mitral/tufted cell that goes to the brain
Bitter, salty, sweet, sour and umami (glutamate) are the 5 tastes. 3 types of taste buds: fungi form (anterior), foliate (sides), circumvallate (back).
Labelled lines model - each type of taste has its own line to a cortex in the brain. Sweet, umami and bitter tastes have GPCR. Sour and salty rely on ion channels
Aphasia: loss of ability to process or create language
Agnosia: loss of ability to process sensory stimuli in a single modality
Anosmia: inability to perceive an odour
Sleep stages
Beta waves: 12-30hz; normal waking levels and alertness
Alpha waves: relaxed awake states; 8-13hz; daydreaming and drowsiness
Theta waves: 4-7hz; when you first fall asleep
Delta waves: 0.5-2hz
NREM
*N1- between sleep and wakefulness; theta waves; hypnogogic hallucinations; feeling like you’re falling - hypnic jerks
*N2 - slightly deeper; more theta waves; sleep spindles which are bursts of rhythmic brain activity; K-complex inhibit cortical arousal and stabilise long term memory
*N3 - slow wave sleep; delta waves; walking or talking in your sleep
REM: rapid eye movement; other muscles are paralysed; most dreaming happens here
You should cycle through these stages every 90 minutes: N1, N2, N3, N2, REM
Circadian rhythms
Regular body rhythms across a 24 hour period
Daylight is a big cue for circadian rhythms
Tend to change as you age
Sleep disorders
Insomnia
Narcolepsy - 5 minutes of deep REM sleep (1/2000); mostly genetic
Sleep apnea - (1/20); can happen many times a night; prevented from going into N3 sleep; gets worse as people get older
Sleepwalking and sleepwalking - mostly genetic; more frequently in children because they have more N3 sleep
Psychoactive drugs
*depressants
- Barbituates, benzodiazepines, alcohol
- depress central nervous system
* enhance brains response to GABA (more chloride in neurons; more resistant to excitation)
*stimulants
- caffeine, nicotine, cocaine (causes the release of dopamine, serotonin and norepinephrine), amphetamines (trigger release of dopamine), meth (trigger release of dopamine), MDMA
- stimulate central nervous system
*hallucinogens
- distorted perception, heightened sensations
- LSD (interferes with serotonin release, visual hallucinations), psilocybin, PCP, ecstasy (increases dopamine, serotonin, stimulates central nervous system, causes hallucinations), marihuana (THC - heightens sensitivity; relaxes central nervous system; stays in body for a week)
*opiates
- depress central nervous system
- analgesic
- morphine, heroin, Vicodin
- act at receptor sites for endorphin
Routes of entry: oral (slow), inhalation (faster, less than 10 seconds), injection (very quick), transdermal (patches), intramuscular
*more likely to become addicted to drugs that take effect more quickly
Reward pathway, tolerance and withdrawal
*When you first experience pleasure, the brain releases dopamine in the ventral tegmental area (VTA) and sends it to the amygdala (emotions), the nucleus accumbens (motor functions), prefrontal cortex (attention, learning) and the hippocampus (forming memories)
*as dopamine goes up, serotonin goes down (partly responsible for feelings of satiation)
*when your brain is overstimulated with dopamine, it’ll shut down some dopamine receptors so that you don’t get as much of a high from the same amount of drugs - tolerance
* if you go through a period of not having the drug, you experience withdrawal because your body has gotten used to the high amount of dopamine from the drug
Attention
*selective attention - endogenous and exogenous
*inattententional blindness: we’re not consciously aware of things that happen in our vision field when our attention is focused away from those things
*change blinds: we fail to notice changes in the environment
Theories of selective attention:
- Broadbent’s early selection theory: all information is processed and then is processed through the sensory register to figure out what we need to focus on and the selective filter filters out everything else
- Deutsch and Deutsch Late Selection theory: you register and assign everything meaning but your selective filter decides what to pass on to conscious awareness
- Treismans Attenuation theory: we have an attenuator that weakest input from the unattended ear. We still assign meaning but it’s lower priority
Priming: exposure to one stimulus influences the response to another stimulus; we attend to information we’ve been selectively primed for.
Resource / spotlight model of attention: we have limited resources which are taxed when we try to divide our attention
*task similarity, task difficulty, practice can determine how well we can multitask
Language
- tends to be processed in the left hemisphere
- Broca’s area: speech production; broca’s aphasia is problems producing speech
- Wernicke’s area: speech perception; wernicke’s aphasia is a problem producing comprehensible speech or understanding other people
- they’re connected by architect fasciculus; if damaged it’s called conduction aphasia
- universalism: thought comes before and determines language
- Piaget: thought influences language
- Vygotsky: language and thought are independent but they converge through development
- linguistic determinism: weak means language influences thought; strong means language determines thought (Whorfian)
Language development
- nativist: children are born with the ability to learn language; Chomsky
- learning theory: children only acquire knowledge through reinforcement
- interactionist: biological and social factors have to interact for la gauge to be produced
