Basics principles of cognitive neuropsychology Flashcards
What is cognitive neuropsychology?
Scientific investigation of cognition (e.g., attention, perception, learning, memory, spoken & written language, thinking and belief formation - where information/knowledge about these processes is obtained via study of individuals whose mental processes are not functioning normally (either due to acquired brain injury or due to a developmental abnormality)
This is in contrast to cognitive psychology which studies the same thing through healthy individuals.
What are the four main principles of cognitive neuropsychology (list)
Modularity
Fractionation
Subtractivity
Universality
What is a cognitive model?
Breaking a cognitive process into the modules and connections between modules.
What is an ‘association’?
What is the main problem with using ‘associations’ as evidence for cognitive models?
Deficits that occur together (e.g., a syndrome - cluster of deficits that often occur together).
Associations reflect neuroanatomical organisation not cognitive processes. In other words, associations imply the close proximity of brain regions involved in the affected processes; but does imply that the processes are involved in the same cognitive model/system.
Indeed, close regions of the brain may perform vastly different, unrelated, functions.
A pattern of results in which performance is impaire don both TASK A and TASK B - an association - might seem to suggest that the tasks share one or more processing mechanisms, given that damage to a shared mechanism would be expected to produce impairment on both tasks. However, the association could also have resulted from two separate deficits, one affecting task A and the other affecting task B. As a consequence, associations are uninformative about underlying processing mechanisms
What is a single dissociation?
What is the main problem with using single dissociations as evidence for divergent processes cognitive models? (i.e., differing underlying cognitiv eprocesses)
Evidence of a deficit occurring in the absence of another deficit.
For example, difficulty perceiving faces but still being able to perceive objects. or difficulty reading non-words, but being able to read words.
The main problem with single dissociations as evidence for a divergent process in cognitive models, is that they could be explained with reference to RESOURCE ARTIFACTS = where one could concludes that both task DO require the same underlying processing mechanism, but one task demands more from these mechanism (i.e., is harder) than the other, and consequently shows greater impairment when the mechanisms are damaged.
Single dissociation = a finding of impaired performance on one task with normal (or at least reliably better) performance on another suggests that the tasks differ in one or more of their underlying processing mechanisms. Resource articfacts are an alternative explanation.
What is a double dissociation?
Why do double dissociations provide good evidence for cognitive models?
One or more patients show poor performance on task A with good performance on task B; while one or more patients who poor performance on Task B with good performance on Task A.
A double dissociation rules out resource artifacts interpretations and provides strong evidence for divergent cognitive processes.
What is a ‘case study’ - why are they often used in cognitive neuropsychology.
Case studies are intensive scientific study (read: multiple experiments) of a single individual with a cognitive deficit.
Variability between individuals is informative, so case studies investigate these individual differences which would otherwise be lost if findings were AVERAGED over lots of individuals (as in group studies). Can still draw conclusions about general models thanks to the notion of universality!
How would a classic neuropsychologist approach classification of aphasias?
How would a cognitive neuropsychologist classify aphasia?
What is the benefit to the latter approach over the former?
Classical neuropsychology defines aphasia based on syndromes (clusters of symptoms often occurring together) due to damage localised to an area of the brain. Whereas cognitive neuropsychology defines aphasia as likely modules/connections damaged within a model of the cognitive processes involved in producing speech.
Classical neuropsychology basis its definition on associations and is relatively insensitive to the breadth/variety of possible aphasic deficits. Cognitive neuropsychology attempts to identify specific processes affected in each individuals aphasia – this has the benefit of allowing for more individualised approaches to intervention and rehabilitation.
Draw the process of model-building through neuropsychological using Lecture 1 - ‘visual-perceptual’ example’ double dissociation between face and object recognition
(DRAWN)
e.g.,
Start with large undefined box that says ‘visual perception’ and refine model given the following cases:
- LM - unable to perceive movement, can perceive form
- S - prosopagnosia w/o agnosia
- CK - agnosia w/o prosopagnosia
- JBR - difficulty picture naming only with objects depicting living things, minimal difficulty with inanimate objects.
Why study cognition in people with abnormal cognition?
- helps to understand normal cognition, to test/develop/extend cognitive theories
- Understand deficits to improve diagnosis and treatment (understand/explain/treat)
Define the following principle of cognitive neuropsychology: Modularity
This is the CORNERSTONE of cognitive neuropsychology.
Modularity describes the notion that cognitive models are comprised of ‘modules’ (i.e., cognitive processors) and the connections between them.
Modules have three main properties:
- Informationally encapsulated = each module has a specific role/performs a specific function. It performs this process ignorant and isolated from other modules.
- Domain Specific = Can only accept one type of input (e.g., visual of letters)
- Mandatory = The system will always try to use this module in the normal way even if it is damaged! Modules are not under voluntary control.
Define the following principle of cognitive neuropsychology: Fractionation
Fractionation describes the notion that brain damage SELECTIVELY damages some modules and not others.
IN OTHER WORDS: brain damage leads to specific deficits as it damages specific modules (like damaging part of a computer, and NOT like a sponge with a bit missing).
also # in cognitive neuropsychology the LOCATION in the brain of modules may be interesting but not necessary knowledge, it doesn’t really matter.
Define the following principle of cognitive neuropsychology: Subtractivity
Subtractivity describes the notion that brain damage/deficits subtract particular cognitive modules or pathways of communication between modules - but CANNOT add new modules or new pathways i.e., system stays the same.
Define the following principle of cognitive neuropsychology: Universality
Universality describes the idea that everyone’s cognitive system is approximately the same. Same models used to do the same functions.
Note that ‘everyone’ is a relative term e.g., English versus Hebrew speakers likely have differences in letter ID module.
What are the three main properties of cognitive ‘modules’?
Modules have three main properties:
- Informationally encapsulated = each module has a specific role/performs a specific function. It performs this process ignorant and isolated from other modules.
- Domain Specific = Can only accept one type of input (e.g., visual of letters)
- Mandatory = The system will always try to use this module in the normal way even if it is damaged! Modules are not under voluntary control.
