Consciousness Flashcards
Consciousness
•moment-by-moment subjective experience of world
-external + internal world (thoughts)
The Brain
- Left + right hemispheres connected by the corpus callosum
* Corpus callosotomy (severing of the corpus callosum): surgery treat patients suffering from epilepsy/chronic seizures
Split Brain, Split Mind
•corpus callosum is severed=2 half brains, each with its own perceptions, thoughts, + consciousness
•Images from left visual field to the right hemisphere + vice versa
-left hemisphere controls right hand + vice versa
Split Brain, Split Mind
- left hemisphere vocal hemisphere: control over speech
* right hemisphere: spatial relations
Split Brain, Split Mind
•Interpreter: left-hemisphere attempts to make sense out of events
–Creates a comprehensible story
–Tries to find patterns, relationships
•Explanation based on info we have
•Only has access to what is given to the hemisphere
Fusiform face area (FFA)
- Area of brain active when ppl look at faces (some evidence that “expertise” area, not just for faces)
- intersection of occipital + temporal cortices, usually larger on the right side
“left-brained” or “right-brained
-right+left hemispheres each specialized for diff tasks
•“right brained”/“left brained” exaggerated in popular media
“left-brained” or “right-brained
under extreme circumstances, 1 side can learn to perform many of the functions generally done by the other side
•If you lose hemisphere, other half can compensate
oVery plastic, adaptive
–Children with Rasmussen’s syndrome who undergo hemispherectomies
stage 1 sleep
-Resting, relaxing - before sleep alpha waves
•Cycle through over night (90 min)
-Light sleep, easily awoken
-theta waves
stage 2 sleep
- Sleep spindles: Takes work to keep yourself asleep, maintain sleep
- k-waves
- Genuine sleep
stage 3 + 4 sleep
-Deep sleep, slow-wave sleep
-Delta waves: big slow waves
•Lacking conscious awareness, but has a sense
Global Workspace Model
-Diff parts of brain responsible for diff functions
–No single area of the brain responsible for “awareness”
REM sleep
-rapid eye movements, dreaming + paralysis of motor systems
•Dreams bizarre, illogical, emotional
•activation of emotion, motivation, reward + visual centres of brain.
•paralysis stop you from moving/flailing around during bizarre dreams
•Alert: beta waves
•Non rem dreams: boring dreams
adaptiveness of sleep
–Restorative theory
–Circadian rhythm theory
–Facilitation of learning theory
Restorative theory
- need to repair ourselves
- recover
Circadian rhythm theory
-evolve to sleep where best time to be inactive
oWe cant do anything useful, most dangerous at night so we don’t move
Facilitation of learning theory
at night, strengthening new connections/synapses
•Consolidates
•Help you learn material
•REM sleep: children spend more time in REM, learning ton of info everyday
•Helpful to dream about it, likely to better learn material
Hypnosis
•social interaction person, responding to suggestions, experiences changes in memory, perception, and/or voluntary action
- Depends more on hypnotized than on skills of hypnotist
- highly suggestible
Hypnosis
–ability to get “lost in activities”/absorbed, block out distractions
activity/absorbed easily
•Altered state of consciousness: hypnotized ppl told they are seeing nonsense syllable, no trouble with stroop test
•Brain activity: black + white photos, tell you it’s coloured, colour processing areas of brain are active
Concentrative meditation
Focus all of your attention on one particular thing
Mindfulness meditation
Let thoughts flow freely, paying attention to them, but not reacting to them
–Long term practice can decrease the reactivity of your autonomic nervous system to stressful events
Limits of Consciousness
-brain is capable of processing & acting on info not consciously aware of
•Blindsight patients/subliminal messages
Subliminal Perception
presented outside of conscious awareness
–Very brief flashes of words/images
–priming tasks activate concepts in someone’s mind, without their awareness
Subliminal Perception
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Subliminal Perception
Much behaviour occurs without awareness/intention
•unconscious mind smart
•Overthinking can result in bad decisions
Verbal overshadowing
ppl rank based on taste do good job without any thought
•When explain it, no idea how to describe it, we end up listening to ourselves bullshitting, based on dumb descriptions, words overshadows, biased ratings
Derren Brown:
The Remarkable Effects of Priming!
takes ad agents, gives them task of making an ad for taxidermy within 30 min
blindsight
-brain damage, no conscious awareness of seeing anything, will better than chance level of correctly guessing
oeven if not visually aware, brain still processing of info even without conscious awareness of seeing anything
oaccess to some visual info not consciously aware of it
Influence by the Unknown: Strahan, Spencer, & Zanna (2002)
- Independent variables: Thirst + type of prime
- Dependent variable: Amount of Kool-Aid consumed
- Priming can persuade people to drink more – only if they want to drink in the first place
- No one can make you do something if you aren’t already motivated to do it
Drugs
-MJ: relaxed mental state, uplifted mood, perceptual + cognitive distortions
•Cocaine: wave of confidence, feel good, alert, energetic, sociable, wide awake
•Meth: Blocks reuptake of dopamine, increases release of dope
Drugs
- MDMA/Ecstasy: energizing effect + slight hallucinations
- less dopamine release + more serotonin release
- Opiates: increase dopamine activation in nucleus accumbens + binding with opiate receptors = relaxation, analgesia, euphoria
- heroin: like orgasm, rush of intense pleasure, evolving into pleasant, relaxed stupor
Qualia
-properties of subjective experiences
Sensation
- detection of external stimuli, responses + transmission of responses to brain
- processing physical property, convert it into neural impulses
Perception
- processing, organization + interpretation of sensory signals in brain
- internal representation of the stimuli + conscious
Perception
-subjective experience
•Every experience subjective
•Adapted to respond to changes in sensory experience
Sensation & Perception
- Everything is experienced in your brain
- The world constructed by you
- Context + Change is important
Sensation:
Going from the world, to your brain
Stimuli need to be translated into chemical/electrical signals for brain to understand Most info (not smell) goes to the thalamus, then directed to part of cortex -info then interpreted as sight, smell, taste
Sensation
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Transduction
Process sensory receptors pass impulses to connecting neurons when they receive stimulation
-takes properties into neural code
Sensory thresholds: Absolute threshold
- min intensity of stimulation that must occur before sensation felt 50% of the time
- the quietest whisper you could hear half the time
Difference threshold
- noticeable difference between two stimuli
- min amount of change required to detect a difference
- depends on what we are comparing, how much change needs to happen to notice a difference
Sensory Adaptation
- stop noticing stimulus once we constantly sensing a stable stimulus
- decrease of sensitivity to a constant level of stimulus
Sensing Chemicals:
Taste
-stimuli chemical substances from food dissolved in saliva
•Taste receptors: in taste buds, send signals to brain (creates experience of taste)
•mix of five basic qualities: sweet, salty, sour, bitter, & umami (savoury)
Sensing Chemicals:
Smell
-stimuli chemical substances dissolved in fluid on mucous membranes in the nose
•olfactory epithelium: thin layer of tissue embedded with smell receptors
-transmit info to olfactory bulb: brain centre for smell
Sensing Chemicals: Taste & Smell
- Thousands of receptors, poorly understood
- Good at good/bad + strong/weak judgments, not at naming odours
- doesn’t go to thalamus
- pleasantness: frontal cortex
- intensity: amygdala
Sensing Chemicals: Taste & Smell
- Smell + texture important: experience occurs in brain (signals are integrated)
- supertaster: lots of taste buds
Touch: Temperature, Pressure, & Pain
- Nerve signals enter thalamus then projected to primary somatosensory cortex - parietal lobe (S1)
- More sensitive areas, more cortical space
- experience occurs in your brain
Touch: Temperature, Pressure, & Pain
- separate temp receptors
- pressure receptors: some at bases of hairs/capsules in skin
- pain receptors: found throughout body
- brain knows you are tickling yourself: cerebellum compensates
Pain
Fast, myelinated fibres: sharp, immediate pain
(protection)
•Slow, nonmyelinated fibres: dull, steady pain (recuperation)
•perceptual experience occurs in the brain
Gate control theory of pain
-pain to be experienced, pain receptors must be activated + neural “gate” in the spinal cord must allow the signals through to the brain
–open: pain is experienced
–closed: pain is reduced (or prevented)
Vision
- myeopia: need another lens to help focus image on retina
- ganglion cells: axons form optical nerve
- 32 regions of brain that are involved in vision
- Primary visual cortex (V1) – occipital
Gate Control Theory of Pain
- pain subjective
- distraction: enough to close gate
- larger sensory fibres can cover up pain signals: rubbing it (activating larger fibres)
Accommodation
Muscles change the shape of the lens
flattening: focus on distant objects
thickening: focus on closer objects
Vision
- dorsal stream/ventral stream
* object agnosia
Photoreceptors
-Convert the energy from light particles (photons) into a chemical reaction that produces an electrical signal
Rods
Retinal cells respond to low levels of light
-black and white perception.
-About 120 million in each retina, located along the edges
•processing info in dark
Visual Transmission
Rods and cones Bipolar, amacrine, horizontal cells Ganglion cells/optic nerve Thalamus Primary visual cortex Ventral “what” stream/Dorsal “where” stream
cornea
- thick, transparent outer layer
- focuses incoming light = refraction
iris
-opaque, circular muscle determines eye’s colour + controls pupil size
retina
-inner surface of back of eyeball
optic nerve
- axons gathered back of retina
* optic nerve creates blind spot – small point at back of retina
sclera
-strong outer coat
lens
-focuses incoming light = refraction on retina
pupil
-small opening in front of lens: contracts/dilates to determine how much light enters
Cones
•cones: fewer but in centre part
- Retinal cells respond to higher levels of light
- colour perception.
- 6 million in each retina, located in the fovea
Vision:
“What” versus “Where”
-Visual areas beyond the primary visual cortex form two parallel processing streams
Ventral “what” stream
-Specialized for perception and recognition of objects
-determining colour and shape
– Object agnosia: don’t know what it is, but knows where it is
Dorsal “where” stream
- Specialized for spatial perception
- determining where an object is and its spatial relation to other objects
Vision: Colour Perception
Three types of cones:
– S: short wavelengths - blue
– M: medium wavelengths - green
– L: long wavelengths - red
Vision: Colour Perception
Perception of color determined by ratio of activity among these three types of receptors
additive colour mixing
•light of diff wavelengths mixed, what you see determined by interaction of wavelengths within eye’s receptors
•almost any colour can be created by combining just 3 wavelengths, so long as one is from long wave end, one from middle, one from short
-red, green, blue
subtractive colour mixing
mixing paints, mixture occurs physical process
•when pigments mixed, they absorb (subtract) each other’s wavelengths + colour we see are wave lengths left over
•yellow, red, blue
Colour blindness (colour vision deficiency)
–Most often genetic, red/green colour blindness is most common, more common in males because carried on the X chromosome
– Red/green colour blindness means that people mix up colours which have some red or green in them
Vision: Colour Perception
- cones
- eyes work in additive mixing way
- acromytopia: inability to process colour
- colour blindness: trouble processing red + green
- red green colourblindness
Proximity
closer two figures are, the more likely we are to group them together and see them as being part of the same object
Object Perception
Gestalt principles of perceptual organization
Similarity
We tend to group figures according to how closely they resemble each other
Good continuation
We tend to interpret intersecting lines as continuous rather than as changing direction radically
Closure
We tend to complete figures that have gaps
Illusory Contours
-tend to perceive contours, even when they don’t exist (but something in the stimulus suggests that they ought to be present)
•everything else becomes background
Bottom-Up and Top-Down Processes
Context is important!
–Same stimulus, different perception
•meet in the middle
•top down
Bottom-up processing
Information is sent from lower-level processing areas to higher level processing areas
Top-down processing
Information from higher- level areas can also influence lower, “earlier” levels in the processing hierarchy
–Expectations inform perceptions
Depth Perception
• Binocular Disparity
Important cue of depth perception
- caused by the distance between the eyes - provides each eye with a slightly different image.
- brain uses the disparity between these two retinal images to compute distances
Depth Perception
•Monocular depth cues
occlusion: near object occludes (blocks) one far away
relative size : far-off objects project smaller retinal image than close
familiar size: we know how large familiar objects are, we can tell how far they are by size of retinal image
Motion parallax
relative movements of objects at various distances from observer
•Anything closer moves opposite your direction fast, anything farther moves in your direction relative to object
Monocular depth cues
linear perspective: parallel lines appear to converge in the distance
texture gradient: uniformly texture surface recedes, its texture continuously becomes denser
position relative to horizon: objects below horizon appear higher in visual field are farther away
•Above horizon that appear lower in visual field farther away
Motion Perception
• Motion sensitive neurons
fatigue of certain motion sensitive neurons leads to motion after-effects (the waterfall illusion)
•brain calculates an object’s perceived movements by monitoring movement of the eyes + also the head, as they track moving object
•motion detectors track image’s motion across retina as receptors in retina fire one after the other
Alcohol
- Lighten sleep
- Wake more frequently
- Trouble returning to sleep
- Less REM sleep
Bipolar, amacrine, horizontal cells
perform on impulses series of sophisticated computation helps system process info
Hearing
- Auditory neurons in thalamus extend axons to primary auditory cortex (A1) – temporal lobe
- Neurons code frequency of stimuli
- Toward rear respond to low frequencies, front to high
Hearing
•Sound waves at outer ear - auditory canal - eardrum - middle ear
•Sound waves make eardrum vibrate (ossicles)
o3 tiny bones: hammer, anvil + stirrup
•ossicles transfer vibrations to oval window, membrane of cochlea (inner ear), fluid-filled tube that curls into snail like shape
Hearing
- basilar membrane: centre of cochlea
- oval window vibrations create pressure waves in inner ear’s fluid, prompt hair cells to bend + cause neurons on basilar membrane to fire
- signal travels to brain via auditory nerve
coarse coding
sensory qualities coded by only few types of receptors each responding to wide range of stimuli
