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