perception and attention

Question 1

define sensation *

Answer 1

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

Question 2

define perception *

Answer 2

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

Question 3

describe the processes of sensation *

Answer 3

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

Question 4

what is bottom up perception *

Answer 4

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

Question 5

what is top down perception *

Answer 5

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

Question 6

overall how is perception an active process *

Answer 6

both top down and bottom up processing works together

Question 7

what are the factors that determine perception *

Answer 7

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

Question 8

eg of how environment alters perception *

Answer 8

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

Question 9

describe cross cultural differences in perception *

Answer 9

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

Question 10

what are gestalt laws *

Answer 10

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

Question 11

describe different parts of the visual cortex

Answer 11

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

Question 12

describe visual agnosia *

Answer 12

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

Question 13

what is apperceptive agnosia *

Answer 13

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

Question 14

describe associative agnosia *

Answer 14

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

Question 15

describe the process of object recognition and where agnosia fits in *

Answer 15

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

Question 16

define attention *

Answer 16

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

Question 17

consequence of focused attention

Answer 17

can miss what you’re not looking for - ie when watching video and counting dont notice something walk across the screen

Question 18

what are the 2 components of attention *

Answer 18

focused attention - the spotlight - focus on what is in front of us

divided attention - paying attention to more thn 1 thing at once

Question 19

what are stimulus factors that affect attention *

Answer 19

intensity

novelity

movement

contrast

repetition

Question 20

what are personal factors that affect attention *

Answer 20

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

Question 21

describe how attention is affected by other aspects of the brain *

Answer 21

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

Question 22

describe the cocktainparty effect *

Answer 22

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

Question 23

describe attention and clinical skills - the stages of learning *

Answer 23

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

Question 24

describe how medical mistakes are related to attention *

Answer 24

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

Question 25

describe medical student syndrome *

Answer 25

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

Question 26

evidence that focus of attention contributes to perception of symptoms *

Answer 26

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

Question 27

describe how the expectation of symptoms alters perception *

Answer 27

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

Question 28

describe pain perception in chronic pain *

Answer 28

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

Question 29

describe the gate theory of pain *

Answer 29

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

Question 30

describe the acute pain process *

Answer 30

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

Question 31

describe the chronic pain pathway *

Answer 31

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

Question 32

why might the body still percieve pain even when the tissue has recovered *

Answer 32

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

Question 33

describe the fear-avoidance model of chronic pain *

Answer 33

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

Question 34

therapeutic approaches to pain *

Answer 34

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