PS2015 Lecture 2 Cognitive Models of Memory

Cognition Lecture 2 l 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) l What type of Memory is Episodic Memory? »Phenomena - what does the model have to explain? »Distinguishing or core features »Consensus Functional architecture l Chapter 1, 5 and 6 from Reisberg

The Mind Is… l A machine made of stupid mechanisms that can interact with one another via connections within neural tissue l Computer analogy is latest in long line of machine comparisons (weaving looms, watermills, aquaducts…) l 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

It may depend upon your span of attention

It may depend upon the fidelity of episodic encoding Low fidelity Hi-fidelity

The Mind Is… Both resistant and misleading 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?

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

Is anyone behind the wheel?

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

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

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

Episodic Memory Phenomena What is an episode? A memento? Core features Functional architecture

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

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

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

Episodic Memory Architecture Consolidation Mechanisms Attentional Control EncodingStorageRetrieval Attentional Control Semantic Records Perceptual Records Binding Context Semantic Records Perceptual Records Binding Context This diagram reflects a widely accepted general consensus

A Specific Example l The constructive memory framework (CMF) Schacter, DL, Norman, KA, and Koutstaal, W. (1998). The cognitive neuroscience of constructive memory. Annual Review of Psychology, 49, 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

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

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