PS2015 Lecture 2 Cognitive Models of Memory

1. PS2015 Lecture 2 Cognitive Models of Memory

2. Cognition Lecture 2 • Key issues where cognitive psychology parts from common sense • 1. Deterministic (by virtue of mechanisms) • 2. Underlying causation is hidden from us (introspectively) • 3. Cognitive psychology has no soul (no single controlling centre) • What type of Memory is Episodic Memory? • Phenomena - what does the model have to explain? • Distinguishing or ‘core’ features • Consensus ‘Functional architecture’ • Chapter 1, 5 and 6 from Reisberg

3. The Mind Is… • A machine made of ‘stupid’ mechanisms that can interact with one another via connections within neural tissue • Computer analogy is latest in long line of machine comparisons (weaving looms, watermills, aquaducts…) • E.G. the library metaphor for Memory • Organization is the key • New experiences and knowledge are filed away systematically • Search and retrieval operations can take advantage of the library organisation to speed things up

4. It may depend upon your ‘span of attention’

5. Hi-fidelity Low fidelity It may depend upon the ‘fidelity’ of episodic encoding

6. The Mind Is… • Both resistant andmisleading to introspection • E.g. memory search mechanisms are ‘hidden’ • E.g. retrieval operations can generate realistic false memories (lecture 4) • Particularly with regard to causal (functional) mechanisms • E.G. the library metaphor for Memory • How is the library managed? By a librarian?

7. Cognitive Psychology has no Soul • Reason 1 concerns the brain:- • a. There may not be a single, controlling brain ‘centre’ • b. Circuits can work independently of one another • Reason 2 concerns function:- • No Homunculi allowed! • they generate an infinite regress which leaves nothing explained

8. Is anyone behind the wheel?

9. Some Common Sense about the Self 3. Responsible for controlling the mind and the body (‘will power’) 4. Determines your individuality 1. Continuous over time, past, present and in the future 2. Singular

10. Key basic assumptions • Our conscious experiences are ‘constructed’ • Many different mechanisms may exist to produce the varieties of conscious experience • Some experiences, associated with higher cognition, may arise from simpler mechanisms working together in concert • Experimental work may allow us to isolate and study each simple mechanism, and how they interact with one another

11. Cognitive Models • Cognitive models are appropriate because they ‘fractionate’ the mind • Cognitive models imply that ‘Reality’ is a construct • Initial questions for any cognitive model • How many mechanisms? • What does each mechanism do? • How do the mechanisms work together within a ‘functional architecture’?

12. Episodic Memory • Phenomena • What is an episode? A memento? • Core features • ‘Functional architecture’

13. Episodic Memory has core features • Memory for specific events from your past • Involves retrieval of content and context (what happened, when it happened and where did it happen) • Associated with a particular kind of conscious experience • ‘mental time travel’ • re-experiencing past sights, sounds, etc

14. Episodic Memory is remarkable • But also fallible, in many different ways • E.g. encoding is (normally) imperfect and/or incomplete • We fail to retain (consolidate) information, and possibly alter the nature of what is retained anyway (leaving the ‘gist’) • Retrieval errors: PTSD, intrusive recollections • ‘False’ memories

15. Processing Stages in Episodic Memory • ENCODING: capture an experience in a trace • Form multiple individual records of attended information • Associate (bind each co-active individual record ) • CONSOLIDATION: make the trace information ‘permanent’ • Abstraction of semantic gist? • Formation of multiple retrieval pathways • ‘offline’ playback mechanisms during sleep and quiet states • RETRIEVAL: access the (correct) trace • Access to the records of attended information via a retrieval cue • Re-activation of attended information and its context

16. Perceptual Records Perceptual Records Semantic Records Semantic Records Context Context Binding Binding Encoding Storage Retrieval Attentional Control Consolidation Mechanisms Attentional Control Episodic Memory ‘Architecture’ This diagram reflects a widely accepted general consensus

17. A Specific Example • The constructive memory framework (CMF) • Schacter, DL, Norman, KA, and Koutstaal, W. (1998). The cognitive neuroscience of constructive memory. Annual Review of Psychology, 49, 289-318. • Invokes multiple brain regions • Some involved in encoding and retrieval • Some involved in either encoding or retrieval • Comprising multiple functions that must interact dynamically with one another

18. CMF Neuroanatomy • The hippocampal formation • ‘Indexing’ of episodes: exactly how is unknown • Necessary both for encoding and retrieval • Damage leads to dense retrograde and anterograde amnesia • The frontal lobes • Strategic control over memory: exactly how is again unknown! • Damage leads to confabulations, delusions, heightened false memory, source amnesia • The entire ‘association’ neocortex • Representation of experienced content • Damage should lead to loss of specific content of prior episodes

19. CMF Retrieval Functions • Retrieval ‘focus’ • Access to the records of attended information via a retrieval cue (by hippocampal pattern completion) • Inhibition of irrelevant information • Re-activation of episodic content (held in the neocortex) • Monitoring/evaluating retrieval products (prefrontally mediated)