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Human Cognitive Architecture & Working Memory Psych 605 Advanced Human Learning Neil H. Schwartz, Ph.D.
The Metaphorical Model of HCA Cognition
Encoding Control Processes
What do we know about the model?
Original Conceptions Broadbent (1958) conceived the model. Concerned with how we attend and retain.
A “pipeline” model: E SR STS LTS Components 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 processing Maintain relevant information in STS Retrieve information from LTS into STS.
Problems with the Model The 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.
Prior Knowledge Sailboat Curtins
Pattern Recognition Feature Processing
sails & hull ? fabric & scallops?
Problems with the Model It 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 Long-Term Store
Short-Term Store PK
All the action is in… Short-Term Store
WORKING MEMORY Long-Term Store
2 Models Sensory Register
Baddeley & Hitch, 1974
What is the difference between STS and WM?
A faculty of mind that can temporarily hold a limited amount of information in a very accessible state with or without awareness.
A concept term derived from Miller et al. (1960) to stand for the way memory is used to plan and carry out behavior.
A pattern of neural firing where the firing pattern, or cell assembly, is active.
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.
Storage & Manipulation
How does WM work?
Principles of the Embedded Processing Model Three faculties
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.
Different Processing limits
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).
Controlled by voluntary & involuntary processes
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.
Unchanged stimuli activate LTM w/o awareness
Principle 4: Unchanged and unimportant physical features of stimuli still activate some features in LTM, but without awareness.
Awareness influences processing
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 Central Executive (directs attention and controls voluntary processing)
Attention can be directed outward to stimuli, or inward to long term memories.
Unchanged Stimuli Novel Stimuli d
a b c
Activated Memory (Short-Term Store) Habituated
Focus of Attention
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 Store Brief Sensory Store
Long-Term storage of some coded features occurs automatically (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 Long-Term Store Central Executive Attention: focus, divide, switch Visual and spatial Perhaps, haptic and kinesthetic
Visual code Linguistic code Binds and holds Binding multidimensional codes Binding Create & Maintain (temporary or durable)
Language-based Speech – heard & spoken Also, lip reading and gestural signs Perhaps, environmental sounds and music
Baddeley’s New Model Central Executive
Sign Lip reading
Music Environmental sound
Which model of WM is better?
Working Memory: Cowan vs. Baddeley Cowan Short-term memory is derived from a temporarily activated subset of information in longterm 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.
Baddeley Verbal-phonological (VP) and visualspatial (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
Short-term Storage Mechanism
Phonological Loop/ Visuospatial Sketchpad
(time-limited by decay)
Focus of Attention