Emotion & Cognition Flashcards
What is double dissociation
-Method of study where both brain damage and non-brain damage data is used to analyse how areas of the brain work
Describe three features of object recognition
- Modular – the object recognition system is built of specialised functional modules
- Constructive – it builds representations from sensory input and contextual information
- Semantic – higher level information about e.g. objects’ functions are built into the representation
How was the visual system originally divided?
- Dorsal pathway or ‘where’ system
- Ventral pathway ‘what’ system
Describe how the visual systems have different representation in the eye
- Temporal cortex (ventral pathway) has all receptive fields in the fovea this lends itself to fine dsircrimination
- Parietal cortex (dorsal pathway) has 60% of receptive fields outside fovea this lends itself to spatial recognition
- Receptive field = area where an object will cause neuron to fire
- Observed in lesion studies with monkeys (lesion to inferotemporal area = poor identification/ lesion to parietal area = poor spatial recognition
what neuropsychological evidence in humans has shown different pathways in object recognition?
-Temporal cortex lesions (ventral) ->
visual agnosia
-> Deficit in recognizing objects
-Parietal cortex lesions (dorsal) ->
Deficits of spatial awareness
-> hemispatial neglect ->
Optic ataxia
-Object tasks activate ventral system (fusiform gyrus)/ Spatial task dorsal activation (parietal cortex) in fMRI studies
What evidence shows the what vs where divide in object recognition is more fine grained is not as broad as originally hypothesised?
- Lesions to ventral system were seen to only effect perception but not vision for action (letter box study) suggesting these may be a better theory rather than just simply “what”
- Ventral system made up of different systems itself including systems for object constancy (recognising object from different angles)/ integrating features into whole object/ recognising functions of the object
Describe the different types of agnosia and what system they effect
- Affect temporal cortex, thus the ventral pathway
- Apperceptive agnosia= deficit in object constancy, caused by lesions to left fusiform cortex
- integrative agnosia= deficit in integration (can’t identify overlapping object but can when same objects are not overlapping/ can not integrate objects into one whole object ) caused by lesions to lateral occiptal complex
- Associative agnosia= unable to associate objects with their function (normally end up picking those that look most alike) caused by lesion to medial temproal lobe
- Prosopagnosia= deficit in face recognition caused by lesion to fusifrom face area (FFA)
- Overall tells us object recognition is a constructive process involving many modules and has a semantic element (meaning is automatically processed) not merely a retinal input but is made up of what we are aware of
How are faces processed?
- Holistically (whole face processed before individual features) which is different to other object recognition
- Faces encoded by spatial relations between features while objects may be coded on individual features themselves
- Possibly evidence for anatomical modularity
What is the expertise hypothesis?
- Face recognition may be as a result of expertise rather than FFA (evidenced inconsistently with experts in different fields such as bird experts)
- No other objects has selective pattern of activation like FFA, except other biological identification processes, showing a dedicated module and contradicts expertise hypo
Explain evidence against anatomical modularity
-Advancements fMRI have lead to multivariate analysis of patterns rather than univariate. Face recognition done across various brain regions not isolated to FFA
What is inattentional blindness?
-Seeing something but not being aware of it as it is not given attention
Define two types of selective attention
- Overt attention= purposely moving head or eyes towards stimulus
- Covert attention= paying attention to something while appearing to pay attention to another stimulus
What is the cocktail party effect?
- An example of covert attention where you can focus on the person you are speaking with as well as well as give attention to neighbouring conversations
- Evidenced with the dichostic listening experiment where participants would remember psychical aspects of speaker but not the content of the unattended channels
What does early selection refer to in terms of attention
- Early selection states that stimuli are processed based on psychical attributes and then are selected by attention
- Cueing effects were used to help evidnece this (arrow that indicated stim gave a quicker reaction time than arrow that indicated opposite location of stim)
- However this theory does not explain how information can still pass through filter (such as hearing ones name in a convo is often picked up upon). Dichotic tasks could also be biased by certain words in unattended stream so were not being filtered out at an early process on a semantic level
What is the spotlight model of attention?
- Attention enhances sensory processing of objects in the spatial location attention is directed
- However study has posed a object selection rather than spatial, objects cued in same object as target were reacted to faster than objects outside of object but same distance away
- Inhibition of return has also shown object selection where if the delay between cue and target becomes longer the uncued condition becomes faster
What does the late selection model of attention refer to?
-All stimuli receive semantic analysis before attentional selection filters what enters into awareness
How does load theory incorporate both early and late selection
- Low perceptual load evidences late selection as main task did not use up all attention so distractor had greater influence as it was also processed increasing rt’s
- High perceptual load evidences early selection as task used all attention so distractor was filtered out reducing rt’s
- fMRI shows high load increases activation in visual cortex in main task but low in non-main task (early selection) and low condition increased activity in task that appeared between main task trials as left over attention increased spotlight (late selection)
What are contralesional stimulus and ipsilesional stimulus?
- contra= things occurring on opposite side to lesion
- Ipsil= things occurring on the same side as the lesion
How can hemisphere neglect be tested?
- Cancellation tests (crossing lines out on page and see what lines are neglected)
- Most common area to cause neglect is damage to tempoparietal junction
Is neglect the same as being blind?
- No, stimuli on each side can often be detected but when presented together the contralesional side will often be missed and the ipsilesional stim being recognised
- This is known as visual extinction
- fMRI still shows activation of damaged hemisphere even though the subject reports no awareness
- Therefore, neglect is a product of a lack of attention, the person is not consciously aware of contra stim but is processing it unconsciously
What has hemisphere neglect contributed in terms of understanding attention?
- Fear stims in neglected field reduced visual extinction, it appears that if a stim is sufficiently meaningful or important it can break through the attention filter despite not being aware of it. Similar to the cocktail party effect
- Also shown objects being similar increase extinction but when processed at a semantic level, words with similar meaning less likely to be neglected compared to presentation of words with different meanings
- Pre-attentive info can affect processing, perceptual load studies that reduce targets also reduced preservation showing unperceived stimulus still influence our behaviour (evidence for late stage processing!)
- Attention operates on internal representations as well as external!, people with neglect report ipsilateral stimulus of memories (Italians and Florence landmark)
- Inhibits spatial memory, those with neglect revisited previously crossed out stimulus more often if the mark was invisible showing issues with internal as well as external attention
- attention operates within objects rather than spatial frame (will draw out right side of images rather than just images on the right side of a space) even if the object rotates attention neglects the original contralesional side again showing object based neglect
- Cueing increases reaction time in ipsilesional field compared to contralesional showing a difficulty in engaging from ipsilesional side
What is the difference between top-down and bottom-up attention?
- bottom-up= stimulus driven, features of objects can determine what we give attention to (these features compete especially if similar) such as a bright light drawing your attention
- top-down= personal relevance (cocktail party), emotional significance, goal relevance, semantic relevance are all examples of top-down approach as these are relevant to the person persons relationship with the object
How is attention competition resolved?
- Bottom-up not sufficient requires top-down measures indicating that a attentional template is required
- Neurons respond selectively to different stimulus’s (some prefer squares, others triangles etc) activity remaining high wins competition for the stimulus associated with the neuron. However, if the stimulus is negative neuron firing is suppressed meaning it will not win the “competition”
- This competition occurs in brain regions which process visual features (inferior temporal cortex) not in a separate specialised region. Neurons in visual region are co-opted to process stimuli and resolve attention competition
- Cueing can prime certain areas to direct attention before person is consciously aware of it
How has EEG evidenced neuron activation in attention
- Cueing can prime certain areas to direct attention before person is consciously aware of it, cue and target being congruent increases activation
- Inhibition of return reflected in firing rates in cueing tasks (higher for valid cue in short delay, higher for invalid cue in longer delay)
How has fMRI evidenced neuron activation in attention
- Cueing tasks have shown locations of stimulus’s are modulated by the brain in V1 (create map of locations on brain) at very early stage
- Competitive interactions happen at multiple points in processing, V4 (involved in feature integration and object representation) activation is lower when items present simultaneously compared to cued (bottom-up) but when asked to focus on just one object this effect disappeared (top-down)
- Activation increased in FFA on face recognition compared to houses depsite both being in visual field. Therefore, attention modulates higher processing regions through activation
What is the biased competition model of attention?
-Competition occurs at the level of object properties and whole objects - as we have seen, monkey neurophysiology and human neuroimaging studies demonstrate attentional modulation of neuronal signals throughout visual cortex (ventral visual stream – the ‘what’ pathway)
How does evidence for the frontoparietal cortex being the source of attentional signals affect the BCMA?
- The BCMA may occur as the result of attentional signals arriving from elsewhere
- Frontopareietal regions activated in preparation for target stimulus (top-down bias signals) not activated when passively attending cue
- Activation of targets were in posterior areas showing a network between the two
How does frequency oscillation (coherence) explain how attention selection is communciated?
-This provides a mechanistic explanation for the two different types of attentional selection – top down, (search task) voluntary attention depends on frequency synchronisation between parietal and prefrontal cortex in the middle frequency band (beta band) whilst bottom-up, (pop out task) reflexive attention depends on frequency synchronisation between these regions in the upper frequency band (gamma band).
How has long and short term shown to be separate
-Double dissociation of lesions studies (K.F preserved long term mem loss of short term mem, H.M opposite)
What is the modal model of memory and evidence against aspects of it?
- Input-> sensory mem-> STM-> LTM
- STM-> LTM through rehearsal, LTM-> STM thorugh retrieval (rehearsal loop)
- Info at each level can be lost through decay
- STM defined as unitary store but has been seen to have multiple seperate stores such as visualspatial and phonological (again shown through double dissociation)
What comprises the WMM?
-Visual-spatial sketchpad/ Central executive/ phonological loop/ episodic buffer
What is the ‘g’ factor and its link to WMM?
- ‘g’ factor defined as either GF= fluid intelligence (reasoning/problem solving) or CF= crystallised intelligence (general knowledge)
- GF was shown to be indicator of WMM (WMM not linked to CF) and specifically linked to executive attention
- Later research showed executive intention was correlated to ability to implement rules and not necessarily a component of fluid intelligence
What is chunking?
- GF indicates ability to build mental program to manage tasks. This is done by chunking, breaking a problem down into more manageable tasks
- WM involves maintenance and manipulation of information and construction/implication of rules to apply to chunking
What is goal neglect?
- Failure to use rules and chunking despite being aware of them is called goal neglect. Lower IQ increases goal neglect
- However more complex rules were seen to increase goal neglect. This suggests the overall complexity of mental program required to complete a task is important when considering link between WM and GF
What is the standard model of the role of the PFC in WMM?
- Info stored in PFC and hold representation to-be-remembered stimuli or template of them. Evidenced through identification direction (of stim) based neuron firing, a temporary representation of the spatial location of the cue. Lesions to PFC showed deficit in this to be remembered info hypothesis showing impaired WM
- PFC organised according to type of information stored
- WMM memory has separate systems for objects and locations like the ventral and dorsal pathways in visual processing, evidenced by higher activation in ventral PFC for patterns/objects and higher activation in dorsal PFC in spatial cues
What evidence is there against the standard model for PFC involvement in WMM?
- Confounds for lesion studies which studied representation as multiple mechanisms used in processing tasks such as attention and strategy
- Chunking uses the PFC so fMRI study of activation in dorsal PFC could of been as a result of manipulating info rather than the PFC being a store of it
- Further animal study showed neurons in PFC can encode both location and identity of an object (not seperate stores) therefore, PFC neurons can adapt to the different info presented
- These neurons were also labelled as for attention or memory and majority were selective for attention. Thus, counters the idea PFC stores representation and is not important for WM but is in fact used for selective attention
- Dorsal vs Ventral argument also may be more to do with what is done with the info rather than what it is. Dorsal= manipulation and Ventral = maintence, PFC is organised thus on type of processing not the type of stimulus
Where is info for representations in WM held and what is now seen as the role of the PFC in WM?
- Multivoxel analysis has visual processing regions also store representations. This means the same regions that are activated in categorising stimulus’s also hold representations of them
- PFC shown to be involved in coding/processing of what attention should be focused on (what is the rule, e.g. is it speed or direction of an object we are looking for?) also this role may involve enhancing attention to internal representations of task relevant stimuli in working memory and manipulating such information by biasing specific sensory regions with signals during working memory (same as what is does to attention)
How is the PFC related to inhibition in learning?
- Damage to PFC seems to stop the ability to surpress information in rule based learning (no negative feedback loop). Those with damage appear to to be unable to surpress a previously learnt rule and carry out a new rule, continuing to apply the original (Wisconsin card sorting task)
- However, performance of these tasks has been seen to be unaffected by those with similar frontal lobe injuries showing the PFC may not affect universal WM. Participants struggle with more realistic tasks though
- Six elements task showed that PFC could be a supervisory system (SAS model), used to facilitate task solving that is not automatic and requires more cognitive resources explaining this deficit with real life scenarios. SAS model is what supervises when new rules have to be learnt (a controller)
What is the criticism of the SAS model?
- Homunculus criticism= If PFC is a controller what is controlling the controller and then what is controlling that controller
- Does not explain how control is carried out just states what is controlled. This lead to fractionating of the PFC to break it down into different components to explain how these systems work together to coordinate functions
What are the subdivisions of the PFC and their function?
- DLPFC/ APFC/ VLPFC = cold cogntion= analytical cognition
- OFC= hot cognition= emotion and value cognition
- All systems communicate with one another
How has the PFC been fractionated into different executive function?
- Shifting = attention shifting
- Updating = update contents of working memory
- Inhibition= inhibiting previously learnt rules and processes
