Human Cognitive Architecture & Working MemoryPsych 605 Advanced Human LearningNeil H. Schwartz, Ph.D.

The Metaphorical Model of HCA

SensoryRegister

Short-TermStore

Long-TermStore

Encoding

Retrieval

Envi

ronm

ent

Cognition

Control Processes

What do we know about the model?

Original ConceptionsBroadbent (1958) conceived the model.

Concerned with how we attend and retain.

A “pipeline” model: E SR STS LTSComponents of the model are separate, such that variables effect memory in some stores and not others.Information is held in an unlimited capacity SR, with some selected for further coding.This further coded information is held in a limited-capacity STS.Then, the coded information is filed in a permanent LTS composed of prior knowledge that is generally organized.

Atkinson & Shiffrin (1968) refined Broadbent’s (1958) model. They added:

Control processes manage the transfer of information between stores.Management of the control processes are voluntary and effortful.The control processes operate to:

Switch attention to selected information for processingMaintain relevant information in STSRetrieve information from LTS into STS.

Problems with the ModelThe model is now seen as obsolete as originally conceived. (Broadbent, 1984)

Learner is active, not passive.Processing is not exclusively “bottom-up”, but also “top down”.Processing is dynamic, strategic, and flexible.Processing is not simply additive.Some processing is sequential, but other processing is parallel.There is more interaction between the stores than originally conceived.Awareness is not always required for content to be in the short-term store.

Inside the Cognitive System

Feature Processi

ngsails & hull ?fabric & scallops?

PriorKnowledge

Pattern Recogniti

on

CurtinsSailboat

top-down

bottom-up

Problems with the ModelIt is not clear that, if SR and STS are actually distinct entities, what constitutes the demarcation.The STS is not essential for access to LTS.Timing and order of information flow is not clear.

For Broadbent, SR fades quickly; STS fades slower; LTS is permanent. For Shiffren SR is coded using LTS information which forms a “trace” in STS.Feature detectors of SR are very quickly “tuned” by prior knowledge from the LTS

Features and concepts in LTS can be automatically activated by incoming stimuli (without awareness).Features and concepts can be held in STS without awareness.

The Way the Original Model Evolved

SensoryRegister

Short-TermStore

Long-TermStore

STIMULUS PK

STIMULUSPK

All the action is in…

Long-TermStore

SensoryRegister

Short-TermStore

Short-TermStoreWORKING MEMORY

2 Models

Cowan, 1988 Baddeley & Hitch, 1974

What is the difference between

STS and WM?

STS WMA faculty of mind that can temporarily hold a limited amount of information in a very accessible state with or without awareness.A pattern of neural firing where the firing pattern, or cell assembly, is active.

A concept term derived from Miller et al. (1960) to stand for the way memory is used to plan and carry out behavior.

The concept was made popular among researchers by Baddeley & Hitch (1974) when they realized that a single module could not account for all kinds of temporary memory.

Temporary Storage Storage & Manipulation

How does WM work?

Principles of the Embedded Processing Model

Three faculties

Different Processing limits

Controlled byvoluntary & involuntary

processes

Unchanged stimuliactivate LTM w/o awareness

Awareness influencesprocessing

Principle 1: Working memory information derives from faculties that are hierarchically arranged. These faculties are: (1) LTM, (2) An activated subset of LTM, (3) A subset of activated memory that is under the light of attention and awareness.

Principle 2: Each faculty has different processing limits. The focus of attention: capacity limited. Activated subset of LTM: time limited. These limitations really show up under non-optimal conditions (e.g. interference between items with similar features).

Principle 3: Focus of attention is controlled conjointly by: (1) voluntary processes and (2) involuntary processes. Voluntary processes are regulated by the central executive system. Involuntary processes are controlled by the attentional orienting system.Principle 4: Unchanged and unimportant physical features of stimuli still activate some features in LTM, but without awareness.

Principle 5: Awareness influences processing. In perception, awareness increases the number of features encoded. In memory, awareness allows new episodic representations to be available for explicit recall.

Cowan: Embedded Processes Model

Long-Term Store

Focus of

Attention

Central Executive(directs attention and controls voluntary processing)

Brief Sensory

Store

Actions

StimuliUnchanged Stimuli

Novel Stimuli

Controlled

Automatic

Volu

ntar

ily A

tten

ded

Hab

itua

ted

Hab

itua

ted

Dis

habi

tuat

ed

Activated Memory(Short-Term Store)

acb

d

ab

cd

Attention can be directed outward to stimuli, or inward to long term memories.

No “filter” is needed; physically unchanged stimuli do not elicit attention (b & c), with the possible exception of significant signals. Unchanged stimuli can enter the focus of attention through voluntary means (a).

Long-Term storage of some coded features occurs auto-matically (b & c). Attentive processing (a & d) results in more elaborate encoding– critical for voluntary retrieval, episodic storage.

Initial phase of sensory storage lasts only several hundred milliseconds (left).

Second phase is one type of activated memory (above), both sensory and semantic activation may last some seconds.

Baddeley: Tripartite Model

Central Executive

VisuospatialSketchpad

PhonologicalLoop

Long-Term Store

Visual and spatial

Perhaps, haptic and kinesthetic

Speech – heard & spoken

Also, lip readingand gestural signs

Language-based

Perhaps, environmentalsounds and music

Attention: focus, divide, switch

Episodic BufferBinds and holds

multidimensional codes(temporary or durable)

Visual codeBinding

Create & Maintain

Linguistic codeBinding

Baddeley’s New ModelCentral

Executive

Episodic Buffer

VSSP Phonological Loop

Artic

ulat

ory

SpeechSignLip reading

MusicEnvironmentalsound

Smell? Taste?Visual Spatial Haptic?

Color Shape Tactile Kinesthetic

Which model of WM is better?

Working Memory: Cowan vs. Baddeley

CowanShort-term memory is derived from a temporarily activated subset of information in long-term memory.This activated subset may decay as a function of time unless it is refreshed, although evidence for decay is tentative at best. A subset of the activated information is the focus of attention, which appears to be limited in chunk capacity. New associations between activated elements can form the focus of attention.

BaddeleyVerbal-phonological (VP) and visual-spatial (VS) representations are held separately, managed and manipulated with the help of attention-related processes, in the central executive (CE).CE was first believed to have a general temporary memory component and a system directive component. Then, the episodic buffer replaced the memory component. The CE is reconceived as the directive (metacognitive) component.Some codes are an activated subset of LTM, some are not.Complex interactive system providing an interface between cognition and action, capable of handling information in a range of modalities and stages of processing.

What is Activated LTM?Maintaining structural representations by dynamic bindings.Manipulating the structural representations.Flexibly reconfiguring the structural representations.Partially decoupling the structural representations from LTM.Controlling LTM retrieval.Encoding new structures into LTM.

Oberauer, (2010)

Working Memory: Cowan vs. Baddeley

Memory Mechanism

Cowan Baddeley

Short-term Storage

Mechanism

Activated Memory

(time-limited by decay)

Phonological Loop/

Visuospatial Sketchpad(temorary hold)

Chunk-based Mechanism

Focus of Attention

(chunk-capacity limited)

Episodic Buffer(binding)

Independentof each other