4a - Attention and Perception (10.02.2020) Flashcards
What is sensation?
- Sensation: The stimulus detection system by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain
- ‘Is there anything out there?’
What is perception?
Perception: The active process of organising the stimulus output and giving it meaning
- ‘What is it, where is it, what is it doing, what is the meaning of the sensory information I am receiving?’
Pathway of sensation and perception
- stimulus energy (light, sound, smell etc)
- > sensory receptors (eyes, ears, nose etc)
- neural impulses
- brain (visual, auditor, olfactory areas)
- perception is in the Brain, sensation is before
Top-down vs bottom-up perception
Top-down:
- Processing in light of existing knowledge
• motives, expectations, experiences, culture
• E.g. ‘backmasking’
Bottom-up:
- sensory information we are receiving
- Individual elements are combined to make a unified perception
- e.g. vibration of the tympanic membrane or activation in the auditory cortex
=> top-down processes impact on bottom-up processes
=> combination of both allows for the best interpretation of the stimulus
Factors Affecting Perception (top down)
Attention (more on this later)
Past experiences -> Poor children and adults overestimate the size of coins compared to affluent people (Ashley et al., 1951)
Current drive state (e.g. arousal state)
-> Hunger: when hungry, more likely to notice food-related stimuli (Seibt
et al., 2007)
Emotions
-> Anxiety increases threat perception (e.g. in PTSD)
Individual values & expectations
-> Telling people a stimulus might be painful makes them more likely to
report pain in response to it (Colloca et al, 2008)
Environment
Cultural background
Cross-Cultural Differences in Perception
- our expectations and what we have been through impact on what we expect to see
- or picture: which animal is the hunter more likely to shoot? (different in western and indigenous people)
Gestalt law
Early 20th century psychologists set out to discover how we organise the parts of our perceptual field into a whole.
We (our brains) try to make sense of the world around us.
Championed ‘top-down’ processing (the sum of the parts is more than the whole)
Figure-ground relations: our tendency to organise stimuli into central or foreground and a background.
- Focus of attention becomes the figure, all else is background
Gestalt laws - continuity
Continuity: When the eye is compelled to move through one object and continue to another object
Gestalt laws - similarity
Similarity: Similar things are perceived as being grouped together. We separate them from things that look different e.g. different colour.
Gestalt laws - proximity
Proximity: Object near each other are grouped together
- we tend to group things together if they are close to each other
Gestalt laws - closure
Closure: Things are grouped together if they seem to complete some entity.
- our mind can fill in these gaps
What are the main components of gestalt laws?
- continuity
- closure
- proximity
- similarity
Disorders of Visual Perception: visual agnosia
Basic vision spared (they can see, their eyes are working, generally their optic nerve is working)
Primary visual cortex can be mostly intact
usually parts of the occipital lobe are damaged
Patient not blind
=> they have a problem e.g. naming object when they see them, they don’t know how to access that information
Knowledgeable about information from other senses (e.g. if they touch an object then naming is typically simple)
Associated with bilateral lesions to the occipital, occiptotemporal, or occipitoparietal lobes.
What are the 2 categories of visual agnosia?
Apperceptive Agnosia: A failure to integrate the
perceptual elements of the stimulus.
Individual elements perceived normally
May be able to indicate discrete awareness of parts of a printed word but cannot organised into a whole; they might not be able to e.g. draw a triangle
Damage to lower level occipital regions
Associative Agnosia: A failure of retrieval of semantic information
Shape, colour, texture can all be perceived normally
Typically sensory specific e.g. if object touched, then recognised
Damage to higher order occipital regions
How can we name and recognise objects visually?
visual perceptual analysis
-> viewer entered representation (creating the image in our minds) -> visual object recognition system -> semantic system -> name retrieval
- first two affected in. apperceptive agnosia
- second two associative agnosia (even though they perceive the triangle they might have problems accessing e.g. the name in there brain)
Attention Informing Perception
Attention is the process of focusing conscious awareness, providing heightened sensitivity to a limited range of experience requiring more intensive processing.
2 processes:
- Focus on a certain aspect - Filter out other information (can be quite powerful)
What are the components of attention?
Focused attention
-> The ‘spotlight’
Divided attention
-> Paying attention to more than one thing at once
What are the stimulus Factors affecting attention?
Intensity Novelty Movement Contrast Repetition
What are the personal Factors Affecting Attention?
Motives Interests Threats Mood Arousal
Attention
• difficult to separate from other processes
• Intertwined with other cognitive processes (e.g. memory and perception)
• Sensory buffers register information for a few seconds which can be used to select which information to focus on.
• Limited capacity for short term memory (we can only perceive so much at once)
• But, there is evidence that we can unconsciously perceive
information not attended to.
External stimuli -> sensory buffers -> limited capacity short term memory -> long-term memory -> responses
What is the cocktail party effect?
= ability to partial out other information in a busy environment
- We can focus our attention on one person’s voice in spite of all the other conversations
- But, what happens when someone says your name in another conversation nearby? -> even though you are not consciously focussing on that, you can send you attention that way
Attention & Clinical Skills
Learning: Cognitive stage (difficult bit, observe demonstrations) -> associative stage (we have a set of instructions in our head) -> autonomous stage (e.g. driving, you do it automatically) - quick, efficient, fluent, effective
- Development of mental resources
- Learning requires explicit instruction through teaching from an ‘expert’, demonstration, and self-observation.
- An effective motor programme has been developed to carry out the broad skill but lacks ability to perform finer subtasks with fluency
- The skill is largely automatic
- Rely on implicit knowledge and motor co-ordination, rather than instruction
Medical Mistakes
But, the more automatic a task, the less conscious control available (loss of focus and attention)
High levels of stress and anxiety can impact performace
Ferner & McDowell (2006):
- Searched UK newspapers and journals
- 44% of deaths caused by errors in planning e.g. giving wrong dose of medication
- 20% caused by slips e.g. injecting air into IV instead of NG tube
Over half of patient deaths were due to unconscious errors that could be the direct consequence of automatic behaviour
Checks needed to reduce errors
MSS
= Medical Student Syndrome
Medical lectures -> normal sensations in the body -> thoughts about sensations -> hypervigilance of the body -> catastrophic interpretation -> anxiety -> physical symptoms -> checking behaviours -> hypervigiliance of body -> ……
- 1960s: studies suggest that unto 60% of medical students developed MSS
- no more likely to develop it than law students
= different results of studies
Perception of Bodily Symptoms
Focus of attention contributes to the perception of our bodily symptoms
Perception of symptoms whilst jogging on a treadmill
(Pennebaker & Lightner, 1980)
56 participants walked on treadmill for 11 minutes on 2 occasions
1st time: wore headphones but heard nothing
2nd time: one group heard amplified sounds of their own breathing, other group heard street sounds (e.g. cars, conversations)
Results: hearing breathing made them perceive more body symptoms. Hearing more cars etc. made them perceive less body symptoms.
Acute Pain: Expectation of perceived bodily symptoms
Stimulus: vibrating piece of sandpaper Students were told they would be: a) Painful -> percieved it more as pain b) Pleasant -> percieved as pleasant c) Not told anything -> neutral perception (Anderson & Pennebaker, 1980)
=> top-down influences
Chronic Pain: Pain perception
- Pain is usually a sign of body damage
- Chronic pain is when pain has been present for greater than 3 months
- At this point, it is likely that original damage has healed
- 28 million people in UK have chronic pain (Fayaz et al., 2016)
- thoughts, emotions etc. colour the pain perception
Gate Theory of pain
(Melzak, 1999)
- Pain signals compete to get through ‘gate’
- ‘Gate’ can be opened or closed by psychological and physical factors.
- Explains pain relief by ‘rubbing it better’
- There are cells in the dorsal horn of the spine that either allow or inhibit the pain to be passed
- Pain is hugely complex, not one part in the brain, lots of different areas play a part
- Focus of attention plays a big part in chronic pain (mindfulness can change the way we percieve pain)
Fear-Avoidance Model of Chronic Pain
- if people perceive pain over a long time they may become quite avoidant of a stimulus that gives them pain
- interaction between pain + mood, thoughts & stress + day-to-day functioning/ behaviour => vicious cycle
- we focus on the pain
- avoid doing things that would make us not think about pain
- Strong relationships between areas
• Pain breeds avoidance which perpetuates stress, low mood, anxiety etc.
