Cognition in Clinical contexts Flashcards
2 Processing streams
Ventral (what) and dorsal (where)
Object recognition (flow chart)
Image > local features > shape representation > object representation
Template matching
Basing perception on memory (internal representation), many rules and templates needed, intuitively plausible
Feature analysis
Lower level factors analysed first searches for characteristic features of an object, supported by neurological information. spatial relationship important
Recognition by components
Arrangement of simple 3D shapes (Geons), impaired when made non-recognisable but can reappear with splats
Gestalt principles
whole visual image more than just the sum of its parts, tries to impose organisation on input, image components grouped on basis of visual properties like colour, laws of perceptual organisation give rise to illusory contours
4 approaches to testing models of cognitive function
- Experimental psychology
- computational modelling (e.g. computer simulating)
- cognitive neuropsychology (e.g. consequences of brain damage)
- cognitive neuroscience (e.g. how the brain implements cognitive functioning)
Bruce and Young’s Model
Face recognition, modular model, distinct pathways with serial processing (dealing with facial expression ect.) - useful as a basic description
Facial recognition widely distributed in the brain but where are core aspects localised?
superior temporal sulcus and the inferior temporal cortex (cells in ITC selective to stimuli) (earlier visual cortex codes for more elementary features)
IAC model - Interactive Activation and Competition
Links between pools of different categories, parallel distribution, connections within a pool are mutually facilitatory and connections between pools are mutually inhibitory (when activating one pool others are inhibited)
Agnosia
Not recognising objects after damage to the occipital/inferior temporal cortex (no visual defects/loss of knowledge of objects)
Apperceptive agnosia
Has knowledge of size and shape of an object but can’t copy and match - damage to shape representation of stage 2 - Lissaur
Associative agnosia
Can copy and match objects but can’t name them - failure in accessing knowledge (mainly damage to stage 3 - object representation) - Lissaur
Prosopagnosia
Profound loss in ability to recognise faces (right inferotemporal lesion) - can recognise people in other ways (voices) - unconscious response of peak skin conductance (covert recognition)
Capgras delusion
recognition without feeling - recognise face but deny identity - no emotional response as no peak skin conductance
Capgras delusion vs prosopagnosia
Loss in ventral stream can result in prosopagnosia and loss in dorsal stream can result in Capgras delusion
Multi-sensory perception
Different senses brought together in the brain - single coherent perspective, more efficient and accurate and so can act on the world
McGurk illusion
“Ba” to ears, “Ga” to eyes, “Da” perceived - looking at lips moving activates the auditory part of the brain
Mirror touch synathesia
Feeling something on their own body when perceiving someone else being touched
Number-space synathesia
See numbers in spatial arrays, larger numbers left to right (could be universal)
Synathesia possible cause
Atypical connectivity between the colour perception region and letter recognition (next to each other), could be more pathways between regions in the brain
Developmental synathesia
genetic- from families - linguistic stimuli
Acquired synesthesia
Sensory deprivation/pharmacologically triggered - not permanent
Evidence synathesia is real
high internal consistency, functional imaging studies (Nunn 2002), slower result in stroop test
Who thought attention and consciousness were connected?
William James 1890
Attention as a process
Selective attention - close to James’ use - the ability to preferentially process a subset of all available attention
Sustained attention - the ability to maintain a state of high alertness/arousal/vigilance.
Attention as a resource
- A set of limited resources for cognitive processing
- Divided attention - our ability to distribute attention over a range of competing inputs
Broadbent and model
People couldn’t tell what language was being spoken in the non-shadowed ear - his filter theory:
Perception -> sensory buffer -> selective filter -> limited capacity processor
(selects information on the basis of its gross physical properties - pitch, loudness, ect.
Triesman’s attenuation model
perception -> sensory buffer -> attenuator -> semantic analysis
(essentially a flexible filter - Reactions to shock - associated words even when didn’t know they had heard them led to Triesman’s model after Broadbent)
Divided attention
Ability affected by: how similar tasks are, how practiced the operator is (Spelke), how difficult tasks are
Visual attention
Only a small area capable of processing visual information (we move our eyes - attention blindness)
Parallel searches vs visual searches in visual attention testing
- Parallel searches have flat set size functions - basic feature analysis (colour/orientation/intensity - popout instantly) - feature integration occurs next - attention is that ‘visual glue’.
- Serial searches have positive set size functions (reaction time increases as set size does). - Conjoint searches - each stimulus processed one at a time
Focus of attention - spotlight?
Objects (Triesman) or locations in space (Posner - cueing paradigm (press a button when they see a target) - valid cues facilitated reaction times and invalid inhibited
- Joula showed attention isn’t grabbed by a spotlight - endogenous cue makes participants shift their spotlight to the right
Automatic behaviours
From extensive practice (e.g reading), rich source of action slips, Automatic processing is inevitable and, once activated, runs to completion
Trait vs state vs clinical anxiety disorders
Trait anxiety - how anxious a person generally is regardless of situation
State anxiety - how anxious in a particular moment
Clinical anxiety disorders - Generalised anxiety disorder, OCDs ect.
How do we study biases? (attention biases and anxiety)
The emotional stroop (slower reactions for threat words) - Watts
Dot-Probe task (drawn to threats - faster to see dot when in the place of threatening word) - Macleod and Mathews (Bradley, Mog and Millar also looked at faces)
Visual search task (find threatening picture faster) - Ohman
Are biases unconditional?
- Already paying attention to threat as in lab task
- Patients under treatment more likely to see threats in periphery not told to look at - Lichtenstein-Vidne
- Grabs attention - not specific to anxiety - Purvis, Lester and Field
Are attentional biases a cause/effect?
Macleod and Clarke 2015 - those who trained negative words showed a higher stress after a stress inducing word - biases can be trained
- Training can be used as treatment
Neglect definition
a failure to report, respond or orient to novel or meaningful contralesional stimuli (Inattention to (usually) the left side of space - ‘lost idea of left’ - inattention
- usually recovers spontaneously within a few weeks/months
- unconscious processing can influence action/decision making (can make decisions based on left side)
Common cause of neglect
A stroke affecting the right side of the brain
Tests for neglect
Line bisection – Mark the midpoint of a line
Picture copying
Cancellation task – Most sensitive – Made harder by using a more “crowded” array
Difference between neglect and a person blind on one side
The blind person would know to move their head to the left, a person with neglect would not know it exists
Neglect frames of reference
- operates in object centered reference frame
- neglect on left of intrinsic axis if rotated
Neglect patients when asked to draw from memory
Could draw the left side
Extinction - a ‘mild form of neglect’
only occurs when two or more objects are presented at the same time (when one object presented on the right and the left can only see the right but when only on the left could see the left) - an impairment of attention rather than perception - visual cortex is processing stimuli (stimuli ‘compete’ for attention)
Non-spatial deficits in attention for neglect:
- Poor working memory
- Show a larger and longer ‘attentional blink’ (If the second target appears quickly after the first you miss the second - your attention ‘blinks’) In neglect the attentional blink takes longer to recover and is a bigger effect
- Also have problems with sustained attention
Neglect tells us that visual processing and attention:
- Operates in multiple spatial and object reference frames
- High degree of processing occur in absence of awareness
- Visual imagery is processed similarly to incoming sensory information
Modal model of memory - Atkinson and Shiffrin
- Information passes between the stores via attention, encoding and retrieval
- maintained in short term store via rehearsal
- Multiple memory stores
Problems with Atkinson and Shiffrin’s model
- Only one short-term store (ignores multitasking)
- Amount of time things spent in STS dictates how well they are stored in LTM
- Patients were found with selective damage to STS but no major difficulties with comprehension, problems solving, general intelligence ect.
Baddeley and Hitch’s working memory model
(Central executive between visuospatial sketchpad and phonological loop)
Phonological loop in Baddeley and Hitch’s working memory model
speech based information - capacity of 7 words or numbers
- tested word length effect (longer words, more syllables remembered less, 1.5 seconds of speech remembered)
(articulatory loop = repeating stuff to yourself)
Visuospatial sketchpad in Baddeley and Hitch’s working memory model
sequences of visually guided actions, seeing “in the mind’s eye” (can’t do two visual tasks at once, can do an auditory and a visual task at the same time), capacity of around 7 (manipulating visual information) - visual spatial information
Memory buffers in Baddeley and Hitch’s working memory model
The central executive organises
Dedicated working memory “buffers” for some specialised types of information, they are independent and controlled by a ‘central executive’, capacity depends on what is being stored, brain damage can result in damage to these buffers
Problems with Baddeley and Hitch’s working memory model
(People are able to remember meaningful information better than unrelated words)
- Found amnesic patients had normal immediate prose recall but relay after delay was highly impaired (finds a problem with Baddeley’s working memory model) (Baddeley and Wilson)
Baddeley’s 2000 working memory model
- Added an episodic buffer (also linked to the episodic LTM) linked to the central executive along with the visuospatial sketchpad (linked to visual semantics) and the phonological loop (also linked to language)
Episodic buffer in Baddeley’s 2000 working memory model
a limited capacity temporary storage system capable of integrating information from sources
- information is integrated across space and time
-important role feeding to and retrieving information from episodic long-term memory
Evidence for reactivation of episodic information
Same patterns of activity are reactivated whenever an event is retrieved (episodic information activates event specific widespread regions of the brain)
Hierarchical process (Hasson) (newer idea)
working memory models separate ongoing information processing from information we are holding in mind, this requires us to accumulate information over time, happens over different timescales in different brain circuits
(Lerner looked for regions of the brain showing coherent activity when reading prose)
Episodic LTM
codes for details in our life, explicit (declarative) = conscious access, contextual details, we are prone to forgetting them (helps us to solve problems, can be adapted)
- Medial temporal lobe
Semantic LTM
Crystallised (stable), explicit knowledge of the world, acontextual, a network of connected concepts, general knowledge, takes longer to absorb but less prone to forgetting
- Lateral temporal cortex
Procedural LTM
(skill memory) - Implicit (non-declarative) = unconscious (you know ‘how’ but its hard to say ‘why’, automatically retrieved, might need to practice a few times before solidified
- Basal ganglia (damage causes movement disorders)
Forgetting of episodic memory
Ebbinghaus (1913) and Berens (2020) - works in snapshots (picks up memory quickly but not in lots of details),
depends on context - context dependent memory and serial position curves (Capitani)
Interactions between LT memory systems
episodic memories depend on semantic knowledge (Bartlett’s War of the Ghosts), semantic processes can bias what is remembered (Loftus and Palmer)
Sleep increases consolidation of LTM systems
- Performance on a sequence learning task increased after sleep (Walker, Brakefield, Hobson and Stickgold)
- Much progress identifying how consolidation occurs (Klinzing, Niethard and Born)
Complementary learning systems (CLS)
Semantic memory cannot be updated too quickly - explicit information is encoded by the episodic system first - system consolidation transforms memories from episodic to semantic
reinforcement learning theory
we learn to predict what the world is like and not be surprised, we get prediction error when our predictions are wrong and this encourages new learning (brain as a prediction machine)
Problems with the Complementary learning system
- Schema consistent information can bypass system consolidation (Tse et al)
- Updated CLS model to account for the rapid semantic updating (Kumaran, Hassabis and McClelland)
Amnesia definition
intelligence intact, attentional spam intact, personality unaffected - ability to take in new information is severely and usually permanently affected
Scourer and Milner amnesiac example
HM - amnesia as surgery removed part of temporal lobes
Normal amnesia causes
damage to the ,medial temporal lobe or connected regions, can occur in head injuries, Alzheimer’s disease, epilepsy, stroke
Anterograde amnesia
After brain injury
Tests for amnesia
- large number of items, test after a delay, recall/recognition, usually verbal and visual
- digit span and spatial span
- procedural memory not affected
- priming - (degrading picture idenfitcation) got better over time
Declarative memory theory
- declarative (episodic and semantic) affected by amnesia, Implicit (priming effects and procedural memory), not affected by amnesia
- Tulving - episodic and semantic memory is different (amnesia only for episodic)
- Squire argued amnesia as a loss in the ability to form any new ‘declarative memories’
Evidence for and against declarative memory theory
+ supported by Bailey (can’t form new semantic memories)
- can form new semantic memories - Vargha-Khadem - could be because they developed amnesia so early in life
Retrograde amnesia
memories before brain injury lost
Standard theory of consolidation
Overtime can learn to consolidate memories in the cortex (memories from long ago remembered)
(but amnesiacs impaired at all retention intervals - should pick equally memorable things across all time frames)
Multiple trace theory (Moscovitch and Nadel)
every time a memory is retrieved, it is re-encoded and a new set of connections (trace) between hippocampus and cortex is made
Standard theory of consolidation vs multiple trace theory
No consensus on who is right - evidence for both
Memories could be transformed over time (becoming part of your general knowledge if not affected by amnesia
Semantic knowledge
- pyramids and palm trees test (Howard and Patterson)
- Associated with lateral temporal cortex (left side), damage in a scan of a semantic dementia patient
Frontal lobes important for the strategic aspects of memory
searching for the right memory, checking whether correct, does it fit with current situation?
Confabulation
retrieving non-relevant information
- provoked/spontaneous
- spontaneous confabulation usually as a result of frontal lobe damage, not due to damage to memory storage, breakdown in memory “executive processes”
Dementia definition
a collection of symptoms associated with impaired cognitive abilities and the ability to carry out day-to-day activities (memory loss, difficulty sustaining attention, language, disorientation in space and time, hallucinations and delusions, mood, social and behavioural changes)
- Not a diagnosis in its own right - can be caused by a number of biological diseases/other factors - an umbrella term
Alzheimer’s disease
neurodegenerative disease, progressive, irreversible deterioration in cognitive abilities and daily function (most over 60) (increasingly common to have a mix of pathologies) (way a person experiences it will differ e.g. physical health)
Alzheimers atrophy
Atrophy - Neuronal loss, reduction in grey and white matter, Topographical progression
- looked at using sMRI
Neurotransmitter production and function impaired with dementia
- Systematic disfunction - altered communication between neurons (damage to basal forebrain)
- Loss of cell bodies in Neucleus Basalis of Meynert very early marker of Alzheimers
- Involved in producing acetlycholine
- Medication to reduce dementia increase production of acetylcholine
Abnormalities develop in the portents which required to maintain and repair neutrons
senile plauques and neurofibillary tangles (a misformed tau protien) (they are both normally found in the neuron)
Measuring localisation of amyloid
PIB PET scan to measure beta amyloid deposition - first in structures of the default mode network
- the posterior cingulate cortex, precuneus and medial prefrontal cortex
Measuring localisation of tau
tau deposition follows Braak staging, localised to MTL in earliest stages of disease, density of tau correlates better with memory loss than amount of beta amyloid
Cognitive symptoms of Alzheimers
episodic ST and LT, semantic memory, working memory (flexibility of representations), spatial memory (people getting lost), Lexicon (word finding)
Assessing dementia
- Assessed in clinic/ novel such as VR
- Assess problems in everyday life e.g. tea making (Rusted and Sheppard observations over 5 years)
Dementia risk factors - genetic
- deterministic genes - chromosomes 21 and 14 (familiar/early onset)
- risk genes - chromosome 19, polygenic risk (Chromosome 19 APOE - allele higher risk (e4 - cognitive structural and functional brain differences from youth)
Modifiable dementia risk factors
eg. education (cognitive reserve - brain development so less likely)
- obesity
- smoking
- depression ect.
dementia can be prevented or slowed due to lifestyle management
Challenges for episodic-semantic distinction
- Interdependence of the systems makes distinction unclear
- Is a memory of a day episodic or become semantic e.g. anniversary
- Some evidence from different pathologies e.g. Semantic Dementia
Semantic dementia
- Neuropathology: Not alzheimers, Degenerate pathology of the polar and inferolateral temporal cortex (sparing of hippocampus in early stages)
- Lose categories - e.g. all vegetables (alzheimers does not lose categories)
Symptoms: Progressive, selective deterioration in semantic memory, reasonably preserved episodic memory
Feature comparison models (Smith et al 1974) (Structure of Semantic memory)
(concepts defined as lists of features)
- Sentence verification task (reaction time) e.g. is a carrot a vegetable? (quick so has lots of characteristic feature - typicality effect)
- Limitations - few concepts can be reduced to a list e.g. a game, features not independent (objects with leaves less likely to have legs than objects with fur)
Prototype Models (Rosch 1973, Galton)
- Prototype models define the centre of a category rather than boundaries (not clear cut)
- Prototypicality effect - defining characteristics of something e.g. criminals (graded structure. some members more representative (prototypical than others)
- Prototypes differ from non-prototypes - most often generated category most prototypical (Mervis); semantic priming ; prototypes share most features with other category members
- Categorised at 3 different levels: superordinate, basic, subordinate
Exemplar Models
specific exemplars rather than ‘averaged’ prototypes (easy to find specific memories of common objects than uncommon ones)
+do not require abstraction, preserve information about variability
-Applies to complex more than simple categories, implies we store every single example of a category
Hierarchical Nets (Collins & Quillian) (A network model)
emphasise the relationship between concepts, relates to feature comparison models
- Concepts represented by Nodes, Nodes connected by Links, Semantic Relatedness
- Slower to verify something which is more links away
Semantic Nets (Collins and Loftus) (A network model)
- Semantic Distance, Spreading activation
- Semantic priming greater for closer items
- False memory effects - DRM - through links around something
- More links activated the faster they become
ACT-R (Anderson) (A network model) (Adaptive control of thought)
- declarative memory is one small part (consists of propositions)
Fan effect - time to make true/false decisions increases with number of items of information
Easier to remember new concepts if more connections- faster when more links activated
Parallel Distributed Processing (McClelland and Rumelhart) (A network model)
Neuron like nodes connected by links with differnt weights
- information processing proceeds in parallel (many patterns of spreading can happen at the same time)
- Allows for spontaneous generalisation and graceful degradation
Schemas and scripts
- Schemas - generic information on situations/general rules than are typically accurate (research has a long history but fell out of fashion when behaviourism was dominant) - between top down and bottom up - can distort memory retrieval (more likely to remember typical things)
- Scripts - structured, ordered sequence of events - a usual process e.g. at a restaurant
4 headings of research in thinking and reasoning
1) Judgement - calculating the likelihood of certain events (component of decision making)
2) Decision making - selecting one out of a number of potential options
3) Problem Solving - from recognising that there is a problem through to developing a solution (cognitive process)
4) Reasoning - component of problem solving that concerns determining what conclusions can be drawn given various statements (premises) are assumed to be true
- this all takes place in the frontal cortex
Judgement under uncertainty
we are bad at understanding percentages/fractions ect. - better but still bad at frequencies - Giggerenzer and Hoffrage 1999
Judgement
Applying heuristics - Kahneman
& Tversky
Availability heuristic - making a judgement on the ease it comes to mind
Representativeness heuristic - likely events are seen as more probable
Anchoring and adjustment - when we adjust our estimate it is anchored to the first estimate
Decision making
Utility theory - should choose the option which has the greatest value to us - are loss averse
- prospect theory explains the Framing effect (frames for loss/gain)
Somatic marker - gut feeling - associating between emotional state and possible actions
Problem solving
(3 parts of a problem: the problem itself (the start state), the things you might do (operators), solution (goal state) - if you’re clear about all of them, then the problem is referred to as well-specified
- Early approaches: behaviourism (trial and error learning, Gestalt Psychology)
- Insight - the “aha” experiences - resulting in a transformation of the problem
- Functional fixedness - we only think about something in the way it is usually used (slows down the way to see solutions)
- Hardest problems are those requiring a move that takes you (temporarily) further away from the goal state
Reasoning
- Deductive reasoning - when the conclusion is certain is premises are true (psychology studies)
- Inductive reasoning - when conclusions are likely to be valid, but require further evidence, and can be regarded as hypotheses (most of science based on)
- Modus ponens: If p then q; p; therefore q
- Modus tollens: If p then q; not q; therefore not p
- (inverse not valid)
- Hypothesis testing
- Wason’s selection task
Dysexecutive Syndrome
Caused by damage to the pre-frontal cortex (mediate higher cognitive functions - executive functions) - traumatic brain injury, tumour, stroke
- Can still have high IQ
- Executive dis-function - e.g. inability to organise and plan, distractibility ect.
Utilisation behaviour - grabs common objects and use them for their function when not socially accessible - impulsive
Testing executive functions
Wisconsin Card Sorting Test - individuals with pre-frontal damage get ‘stuck’, carrying on sorting by a rule even if told it was wrong (perservation)
Stroop test - Individuals with prefrontal damage sometimes cannot avoid saying the colour of the word (cannot inhibit the more automatic response)
Hayling Test - sentences read with the last word missing (Part A complete with appropriate word, Part B complete with an inappropriate word) - Individuals with damage to frontal cortex struggle to say an unrelated word - cannot generate a strategy to find unrelated word (some people can just be slower)
MET - multiple errands test - Shallice and Burgess - takes place in real world - carry out errands on a street (8 tasks) in 15 minutes (can use VR now) (individuals failed with plan formulation, marker creation or triggering and evaluation and goal articulation)
Theories of executive control: Supervisory attentional system (SAS) - Norman and Shallice
action automatic - attention can be automatically drawn to an object - making tea - contention scheduling)
or under attentional control - involving planning, troubleshooting, dangerous or technically difficult - learning to drive a car
Problems:
Perseveration - once activated, schemas persist wituout SAS input
Distractibility - when no dominant schema, the SAS would normally inhibit responses
- Explains performance on tests but no mention to situations like multi-tasking
Cognitive behavioural therapy
CBT - a type of psychotherapy widely practiced, recommended by National Institute for Health and Clinical Excellence (NICE) - first line treatment for depression and anxiety disorders
- Talking and doing therapy
- Practiced, goal orientated (to improve issues)
- Explores how thought and thinking processes effect how we feel and behave, teaches coping skills
In cognitive behavioural therapy what is central to the change process
Cognitive models posits that thoughts and thinking patterns are an integral part of emotional distress
(Behaviours can also effect how we feel and what we think, and might even effect the situation itself)
Cognitive model argues that mental health problems can be understood through unhelpful or unrealistic beliefs
Hot cross bun model (Padesky)
Environment leads to to thoughts
Thoughts related to body sensations, feelings and behaviour
Where do thoughts come from in CBT?
We all hold beliefs, attitudes and assumptions about the world which influence thinking in the moment, learnt from life experiences and their interaction with our genetics and personality (nature and nurture)
Cognitive vulnerability model
Life experiences and genetic factors and temperament/personality along with core beliefs, attitudes and assumptions along with a triggering event effect thoughts
Thoughts still related to body sensations, behaviour and feelings
Beck and his negative cognitive triad
Self, world and future connected
Depression characterised by a negative cognitive triad - a lot of evidence for model - e.g. people with depression/anxiety report more negative thoughts
Beck first described CBT for depression in 1967
Cognitive behavioural therapy in practice (CBT)
active, collaborative, scientific, focused on here-and-now problems, works towards specific goals, time limited, structured
- collecting and weighting up evidence for unhelpful thoughts, generate alternative ideas and testing them out with behavioural experiments
- Use of thought records to help identify patterns of thinking associated with painful emotional experiences
- Develop shared formula - a cross sectional understanding (could be using the hot cross bun method) to explore patterns of underlying beliefs, attitudes and assumptions and where these may have come from
Evidence supporting CBT
- DeRubeis et al (2005) - found no difference in outcomes between CBT and antidepressant medication at 8 or 16 weeks (both better than placebo)
- Hollon (2005) - following the cognitive therapy patients were less likely to relapse into depression over 2 years
Psychobiological view of appetite
eating is a consequence of physiological processes monitoring nutrient status (cannot explain - overeating and the rise in obesity, eating disorders ect.)
Cognitive theories of susceptibility to overeat
Externality theory - individual differences in how people respond to cues telling them when to eat (internal and external (more external then obesity))
Restraint theory - cognitions of not to overeat (makes food more desirable)
Emotional eating - food for pleasure and reward
Tests for attention in appetite
- Food dot probe task (reaction time with food related or not) - attentional bias for food cues
- Food stroop task (slower colour naming time for food related items)
Role of attention in eating
- Attentional capacity is limited - inattention while eating could promote overconsumption, inattention between meals may lead to poor awareness of interoceptive (e.g. bodily cues relating to appetite
- Eating while distracted consistently leads to greater intake and poorer memory of what consumed, obese children spend more time in sedentary behaviours and more TV
Mindfulness in eating
- attending to food during meals should lead to better control of intake
- training awareness of appetite sensations should lead to better appetite control
Food liking in eating
- Learning influences food liking, Flavour preferences established in childhood will track into adulthood - encouraging healthy eating habits in early life important for the prevention of adulthood obesity (don’t treat healthy food for medicine and have unhealthy as a treat)
Sensory specific satiety
Variety influences how liking change (decrease in palatability of recently eaten food - decrease in desire for a food just eaten while still desiring more of other food (space for dessert)
obese people have no decrease in palatability for eaten foo
Expectations influence food liking
- Assimilation - expected and sensed experience combine so the actual evaluation is closer to the expectations seen when the food is evaluated without prior expectations (how much enjoyed determined by expectations)
- Contrast effect - when expected and sensed sensory experience are very different resulting in a decrease in the rated quality of the food (told it was a savoury dessert vs ice cream (smoked salmon ice cream))
Portion size and appetite
Portion size selection - plate clearing occurs 91% of the time, decisions about how much we serve ourselves are important - Increasing portion size increases intake, visual cues important
Expectations influence portion size selection
- Ideal portion size measure, expected fillingness of food satisfaction, expected liking (Ideal portion size associated with expected fillingness and food utility)
Modifying perceptions to reduce obesity
- Establish healthy eating in childhood
- Change eating environment (e.g. plate size)
- Increase expectations that foods will be filling so small portions are selected
- Regulate advertising high fat sugar foods
- Decrease variety
- Make all food taste the same
Memory and appetite
Studies by Higgs indicate that thinking about recently eaten food reduces intake at the next eating episode - memory manipulations did not influence food liking
- Disrupting encoding of memories while eating results in overeating at the next meal (could contribute to the relationship between TV watching and obesity)
- Reducing intake by enhancing memories - pay attention to food means less snacks
- Aim to enhance meal memories by increasing attention to experience of eating, slowing down eating rate, discouraging distractions while eating
Philosophical Background: Constraint of determinism,
Metaphysical libertarianism and hard determinism
Metaphysical libertarianism - determinism is false and free will exists
Hard determinism - determinism is true and free will is false
- Both assume determinism is the relevant factor in free will
Philosophical Background:
Incompatibilists vs compatibilists
Incompatibilists - determinism is the crucial factor in free will (metaphysical libertarianism and hard determinism), question of if conscious choice determined by something else (we are not free)
Compatibilists - determinism is not relevant and alternatives are key (e.g. free from coercion or your conscious self is contributing in some way to the decision but is not the sole determination)
Libet - the unconscious initiation of voluntary acts
- Participants choose a time to press a button and stop a dot rotating round a clock face and report where the dot was when they felt the urge to stop
- Electrodes on prefrontal motor areas
record the readiness potential (RP) –
a negative shift in electrical potential
occurring before action. Reported will to act was around 200 ms
before the action, the RP began some 350 ms before
Criticisms of Libet -
- Action is trivial - real decision was to join the study
- the time of will may vary depending on the division of attention
- assumes that the RP reflects a preconscious decision process
- Assesses only the choice of time not of the action
- EEG had limited spatial resolution - only limited insight into specific brain regions
Challenging the readiness potential - Schurger, Sitt, & Dehaene (2012)
showed that the RP may not reflect a preconscious decision process
Volition - Soon et al 2008
participants choose time and which button to press (said which letter showed in a stream of letters)
- Pattern classification algorithm identified areas of the prefrontal cortex predicting which hand pressed the button 7 seconds before a decision was made - earlier stage in causal change (areas identified known to be involved in prospective memory)
Anarchic hand
A person’s hand has a will of it’s own (alien hand syndrome - alien hand used to be when someone dissociates themselves from it) - causes considerable stress
- thought to be caused by a disconnection of the hemispheres but would need to be fully separated - damage to SMA impairs the voluntary circuit and can lead to utilisation behaviour
Fried et al. (2011) - The Libet paradigm with single neuron recordings
- Placement of electrodes in the brain. driven by clinical need more useful as more precise - can record the firing patterns of single neurons in
awake functioning individuals - Time of conscious intention could be
predicted by small subpopulations of these - Fried et al. show that the SMA not pre-SMA contained more active
neurons before the feeling of intention i.e. it occurs later in the chain - Suggests the feeling of intention may correspond to the moment when an
unconscious plan is enacted - Volition as ‘intention in action’ - still potentially challenged by Schurger’s accumulator model.
Are ‘free will’ and ‘free won’t’ seperate
subpopulations of neurons decreased in activity in pre-SMA - evidence for inhibitory component (if there is something to stop an action then there could be free won’t - implies that suppression of action and its voluntary initiation are closely linked
- the urge to move can exist independently of action
Voluntary driven action
- the loop through the basal ganglia integrates a range
of cortical signals to drive appropriate actions - Dopaminergic inputs from substantial nigra to striatum provide modulation
based on reward - Hence voluntary action can be seen as flexible intelligent interaction with
current and historical context – not without cause but with a wider context
Frontal lobotomy (orbital lobotomy)
- Calming effect on monkeys and wanted to try in humans
- Egas Moniz
- crude, different parts of brain damaged and so different outcomes
- introduction of Thorazine by GSM marked end
How much of the human brain is the frontal region?
29%
Impact of damage to frontal cortex (impulse control and addiction)
impaired decision making and less delayed gratification (persist with disadvantageous decks Iowa gambling task)
Addiction
3 characteristics - compulsive drug seeking and taking, inability to stop and high rates of relapse after cessation
drugs become more wanted and less liked - many try drugs but few become addicted
Brains of addicts
Reduced cortical grey matter in alcoholics and smaller volume of pre frontal lobe in poly substance abusers
Pre frontal model on addiction - Jentsch & Taylor, Goldstein & Volkow
Drug induced structural and functional changes in prefrontal regions -> lower impulse control -> increased likelihood of taking drugs -> higher drug intake -> (circular)
Don’t know cause and effect
Changes in addict rat brains
structural changes in dendritic spikes (ethical limitations with people)
PET scan of glucose metabolism in control brains and cocaine abusers
reduced OFC function in cocaine users compared to control subjects during protracted withdrawal - cue induced cocaine craving activates the ACC and OFC
Which system is addiction related to?
The limbic system - a set of brain structures, which are involved in natural reward and drug reward. Drugs can produce long-lasting changes to the limbic system, which can lead to addiction.
