Introduction
What is Colhearts' biggest critique of neuroimaging so far?
They cannot distinguish between competing psychological theories.
Which three disclaimers does Colheart give about his review?
- he focuses on psychological findings, not on localization
- he does not say neuroimaging won't be capable of distinguishing between theories in the future
- he will not give a full overview of all the literature
Which 6 examples does Colheart describe to highlight his point?
- recognition memory (remembering v/s knowing)
- episodic memory
- inattentional blindness
- facial processing
- working memory
- representing the intentions of others
which two types of sceptics exists regarding fMRI and cognitive theory?
- Skeptics who claim cognition is analyzed at a more abstract level than neural implementation (strong assumption of multiple realizability) - suggesting that imaging cannot, in principle, add anything fundamentally new to cognitive theory
- Skeptics who concede that neuroscientific data could hypothetically constrain cognitive theory, but are unconvinced that fMRI data are capable of providing such constraints.
Explain multiple realizability
Cognitive processes can be implemented in various forms of "hardware," not just the specific neural structures of the brain. Neuroscientific data only explains how cognitive processes are implemented in the brain. Still, they cannot inform or constrain theories about the identity, nature, or interrelationships of cognitive processes themselves.
What are the 8 reasons to neurally embellish a theory?
- Mitigate the Risk of Descriptive Abstractions (grounding theories in a physical reality)
- Help Resolve Model Mimicry Through Out-of-Sample Tests (finding a neural basis to distinguish between models that make similar predictions in the behavioral domain)
- Make a model falsifiable
- Multiple realizability does not imply infinite realizability (Even if a theory could be implemented in various neural ways, neuroscientific data can still be informative; data can rule out certain possible implementations, thereby constraining the theory).
- Promotes Productive Integrative Work (e. g. neural and cognitive)
- Neuroscience Needs Theory
- Neurally embellishing a theory allows it to benefit from neuroscience data and makes it potentially falsifiable by such data, which contributes more strongly to the progress of science
- A neural embellishment provides a commitment to how internal states are implemented in the brain, allowing them to be measured directly using neuroimaging, isolated from other confounding processes.
What is the consistency fallacy?
When one claims that some piece of evidence supports a theory without showing either how an alternative outcome could have contradicted that theory, or how the evidence contradicts another theory (making it non-falsifiable).
What are the easy and the hard problems of embellishing cognitive theories?
- How to express a cognitive theory in a way that makes some commitment to a neural implementation.
- How cognitive theory can be neurally embellished in a way that specifically enables an effective test with fMRI (hard).
Solutions to seeing whether fMRI data falsifies a cognitive theory or just its neural embellishment
Dissociation logic
The two main types of dissociation evidence
- Single Dissociation: occurs when an experimental manipulation affects activation in one brain region more than in another. This can be accounted for by a single-process model, where both brain areas respond to the same underlying process but differ in their responsivity.
- Double Dissociation: occurs when manipulation A activates brain region X more than region Y, while manipulation B activates region Y more than region X.
A cross-over double dissociation, where the effects are qualitatively opposite in the two regions (A affects X positively and Y negatively, while B affects X negatively and Y positively, for instance), is considered the strongest form of evidence for independence
What is the biggest problem with dissociation logic?
Inferential risk: A single-process model could, in principle, explain even a "pure" double dissociation if brain regions are assumed to have complex response functions to a single underlying variable
What often goes wrong when trying to interpret brain mapping?
The whole brain is often to some extent involved in action; therefore, making conclusions about behavior based on the level of activation is problematic.
Name three potential causes for the same brain area being implicated for multiple functions
1. poor localization of the instrument
2. poor operationalization of the experimentor
3. unknown brain ontology
What is the readiness potential?
The slow buildup of electrical potential that can be observed with EEG before movement.
Traditionally interpreted as planning/preparation.
What was Libet's finding?
He found a neural precursor of voluntary action, the 'readiness potential' (RP), which began on average 635 ms before action.
What do schruder et al. suggest opposing Libet?
Schurger et al. argue that the brain activity seen before voluntary movement might not just be about planning, but could partly reflect the brain's ongoing random fluctuations influencing when a decision to act spontaneously occurs.