perception and attention Flashcards
define sensation *
the stimulus detection system by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent into the brain
it is our senses asking - ‘is there anything out there’ and thsi being translated into nerve impulses
define perception *
the active process of organising the stimulus output and giving it meaning
ie what is it, where and what is it doing
this is giving meaning to the sensory information
describe the processes of sensation *
stimulus energy (light/sound/smell)
this is detected by sensory receptors eg eyes, ears, nose etc
this is translated into nerve impulses which go to the brain
eg the visual, auditory and olfactory areas
what is bottom up perception *
individual elements are combined to make a unifined perception
eg acoustic wave = vibration of the tympanic membrane = activation of the auditory cortex = interpretation of the stimulu s
what is top down perception *
processing in light of existing knowledge
ie the context, grammer, motivations, expectations
they determine how we percieve bottom up perception
eg backmasking is when a song is recorded backward so you can hear a message if you play the track backwards - when we know the context it influences what we hear ie the 1st time dont hear anything, buit listening to song when know context of the message means you hear it
overall how is perception an active process *
both top down and bottom up processing works together
what are the factors that determine perception *
attention
past experiences - poor children over estimate the size of coins compared to affulent children
current drive/arousal state - eg when hungry, more likely to notice food related stimuli
emotions - anxiety increases threat perception eg in PTSD
individuals values and expectations - telling a pt that a stimulus will be painful makes them more likely to report pain in response to it
environment - what we know about the world and what we know to be fact influences how we percieve stimuli
cultural background
eg of how environment alters perception *
when see people in a room we assume that all of the room is R angle and so assume the height of people but actually the room can be at angles
this is based on what we about the world, factual info about how we know the world to be and how this influences the bottom up perception - ie that rooms are rectangular etc
describe cross cultural differences in perception *
in western cultures see the image above womens head as window, more indian culture see this as a pail of water
in second image - western people see the person shooting the deer because that is what arrow is aimed at; whereas indian see that it is shooting at elephant because that is what people hunt
what are gestalt laws *
he championed top-down processing
laws of perceptual organisation
figure- ground relations - our tendancy to organise stimuli into central or foreground and a background
continuity - when the eye is compelled to move through 1 object and continue to another object eg see the leaf as a continuation of the H, see all the dots as continuous even though they are distinct structures
similarity - similar things are percieved as being grouped together eg separate things of different coolours even w/o thinking about it
proximetry - objects near each other are grouped together even if they are distinct and different colours etc
closure - things are grouped together even if they seem to complete some entity - ie fill in gaps in WFF panda so that it looks like a panda even if the line isnt there
describe different parts of the visual cortex
visual info comes through eye - hits retina - through optic nerve - through the thalamas - relayed to the occipital part of brain
V1 and V2 are basic processing parts of the brain
as different elements of the visual info is made sense of - more discrete occipital areas are involved - they all perceive differnet aspects of vision eg form, colour, movement and shape
describe visual agnosia *
basic vision is spared
primary visual cortex is mostly in tact
pt is not blind
they way they perceive and access info about stimulus about them is damaged
pts are knowledgable about information from other senses - eg if they touch an object naming it is simople, but they cant name itr just by seeing it
part occipital lobe is damaged
what is apperceptive agnosia *
a failure to integrate the perceptual elements of the stimulus
individual elements are percieved normally eg each of the edges of the triangle
may be able to indicate discrete awareness of parts of a printed word but cant be organised into a whole eg cant draw the full triangle
there is damage to lower level occipital regions
bilateral damage
describe associative agnosia *
a failure of retrival of semantic info
shape, colour and texture can all be percieved normally
typically sensory specific - if the object is touched, then it is recognised - access the info from different senses
there is damage to higher order occipital regions - V1/2 intact - can copy the triangle but cant say what it is
describe the process of object recognition and where agnosia fits in *
visual perceptual analysis
then viewer centred representation - create the triangle visually in minds - cant do these 2 steps in apperceptive agnosia
then visual object recognition system
then semantic system - access info ie the name ‘triangle’ - cant do these 2 steps in associative agnosia - cant access the facts even though the perception and visualisation of the object is fine
name retrival
define attention *
the process of focusing conscious awareness, providing heightened sensitivity to a limited range of experience requiring more intenisve processing
there are 2 processes - focussing on a certain aspect, and filtering out other information
consequence of focused attention
can miss what you’re not looking for - ie when watching video and counting dont notice something walk across the screen
what are the 2 components of attention *
focused attention - the spotlight - focus on what is in front of us
divided attention - paying attention to more thn 1 thing at once
what are stimulus factors that affect attention *
intensity
novelity
movement
contrast
repetition
what are personal factors that affect attention *
motives - eg if food shop when hungry more likely to get sweeter food
interests - more interest = more attention
threats eg have PTSD - more focused on threatening stimuli
mood
arousal
describe how attention is affected by other aspects of the brain *
intertwined with other cognitive processes eg memory and perception
sensory buffers (other senses) register info for a few seconds which can be used to select which info to focus on - this info goes to short term memory
there is a limited capacity for short term memory
the info deemed important goes to long term memory
this causes a response
we unconsciously percieve info that we didnt intend to
describe the cocktainparty effect *
we can focus our attention on 1 voice despite all the other conversations around us
but when someone says our name our attention subconsiously is sent to the other conversation
describe attention and clinical skills - the stages of learning *
cognitive phase - learning requires explicit instructions through teaching from an expert, demonstration and self-observation - here you learn the steps
associatiev phase - as effective motor program has been developed to carry out the broad skill, but lacks ability to perform finer subtasks with fluency - generally able but takes focus
autonomous phase - the skill is automatioc, rely on impliciy knowledge and motor coordination rather than instruction
describe how medical mistakes are related to attention *
the more automatic the task, the less conscious control available
high levels of stress and anxiety can impact performance
44% of deaths were caused by planning eg giving wrong dose because task is autonomous so dont give it conscious attention
20% caused by slips eg injecting air into IV instead of NG tube
therefore checks need to be in place to reduce the errors
describe medical student syndrome *
when have medical lectures, normal body sensations lead to thoughts about them = hypervigilance of body = catastrophic interpretation = anxiety = physical symptoms = checking behaviours = hypervigilance
ie it is a cycle
evidence of how top down knowledge and how we think about things alters our perception
however medical students were no more likely to develop MSS than law students
evidence that focus of attention contributes to perception of symptoms *
Pennebaker and Lightner - 1980
participants walked on treadmill for 11mins twice
1st time wore headphones but heard nothing
2nd time 1 group heard amplified sounds of own breathing, other group heard street sounds eg cars
those focusing on body percieved more bodily sensations compared to those focusing on the street
describe how the expectation of symptoms alters perception *
anderson and pennebaker
stimulus - vibrating sandpaper that students had to put hand on
students were told that it would be painful, pleasant or weren’t told anything
those who were told is would be painful percieved it to be more painful
another example of top down influences
describe pain perception in chronic pain *
pain is usually a sign of body damage
chronic pain is when pain has been present for >3 months - at which point is likely that the original damage has healed
this because the way we perceive pain is important - the way we think about the pain stim, suffering we experience and the way we respond to it
describe the gate theory of pain *
pain signals compete to get through the ‘gate’ - the gate can be opened/closed by psychological and physical factors
cells in the dorsal horn inhibit/allow pain to go to the brain to be percieved
ie you can have pain relief by rubbing it better
in acute pain the dorsal horn might use an opiod system to reduce the pain
in chronic pain the pain gets through and is opercieved by the brain, even though the tissue has healed
describe the acute pain process *
1 - inflammation (damaged cells release sensitising chemicals), transduction (noxious stimuli translated into electrical activity at sensory nerve endings)
2 - conduction - passage of ap along neurons
3 - transmission - synaptic transfer and modulation of input from 1 neuron to the next using chemical messengers
4- modulation - anti-nociceotion neurons originating in the brainstem descend to the spinal cord and release chemical messengers that inhibit transmission of painful stimuli
5 - perception - recognition and reaction in the brain - complex interactions involve the thalamus, the sensory cortex, limbic system and RAS
describe the chronic pain pathway *
1 - neurogenic inflammation - increased prostanoid production at site of pain produces allodynia and hyperalgesia and generates spontaneous pain
2 - damaged nerve - damaged sensory nerves may send constant pain signals like an alarm taht wont stop
sensitisation - repeated pain signals produces changes in the nervous system - pain becomes more painful
loss of control - normally innocuous stimuli become painful, once activated, even small movements/deformity of tiddues becomes painful
5 - mental overload - possible neurochemical link between pain and memory, high incidence of depression, anxiety - suffering increases pain
why might the body still percieve pain even when the tissue has recovered *
the somatosensory cortex registers which part of the body pain is in and the intensity of the pain - there is less activity here when patients forcus their attention away from the pain
the insular cortex integrates sensory and emotional cognitive states, fell empathy for other’s pain
thalamus - recieves brain signals from spinal cord and relays them to higher brain regions
insular, thal and limbic - emotional parts of the brain - they light up in pain
anygdala - anticipates pain and reacts to percieved threats
prefrontal cortex - processes pain signals rationally and plans action - active when consiously trying to reduce pain - involved in thinking, perception and making sense of the world
medial prefrontal gyrus - focuses on negative personal implications of pain - heightened activity is seen in anxious people
right lateral orbitofrontal cortex - evalulates sensory stimuli and decides on a response - particularly if fear is involved - mindfulness meditation calms this response
nucleus accumbens - releases dopamine and serotonin during pleasure or pain
anterior cingulate cortex - registers unpleasant feelings when things go wrong, either physically or emotionally - people who are highly sensitive to pain have more activity here
from all of these areas involved in pain we can see that it is influenced by how we think, feel, emotional state and how we process thee things on a psychological level
describe the fear-avoidance model of chronic pain *
pain, mood thoughts and stress, and day to day functioning are interelated - there is a viscious cycle
you avoid things that cause pain
therefore only focus on pain
also means stop doing things you want = stress
therefore pain increases
therapeutic approaches to pain *
focus of attention - decrease in pain when people focus on loved one’s photo while exposed to a heated probe (however more we think about pain - more likely we are to experience pain long term)
decrease in pain when people use mindfulness meditation - change way we make sense of the sensory information that the body is sending up through the dorsal horn
reduction in pain of people with fibromyalgia wgo reported less pain after recieving cognitive behavioural therapy or mindfulness or acceptence and commital therapy - makes a difference about how people perceive the world and how they see themselves
