Short Term Memory and Working Memory

A comprehensive vocabulary review of Module 4 covering Short Term Memory and Working Memory models, capacities, codes, interference, and individual differences.

Modal Model (Atkinson & Shiffrin, 1968)

A classical structural model of memory positing three distinct, sequential storage stores: sensory register, short-term store, and long-term store, where information is transferred between isolated compartments.

Activation Model (Cowan, 1988)

A dynamic memory model proposing that working memory consists of an activated subset of features from long-term memory, within which a movable focus of attention (spotlight) operates.

Serial Position Curve

A U-shaped curve depicting the probability of recall as a function of the order or position in which an item was presented in a list during immediate free recall.

Working Memory Model (Baddeley & Hitch, 1974)

A multi-component memory architecture comprising a central executive for processing and resource allocation alongside temporary storage buffers (phonological loop, visuo-spatial sketchpad, and episodic buffer).

Mental Rotation Task (Shepard & Metzler, 1971)

A visual-spatial reasoning experiment showing that the time required to decide whether two rotated 3D block figures are identical increases linearly with the degree of physical rotation required.

Sensory Register

The earliest storage area in Atkinson and Shiffrin's modal model that holds raw sensory input for a fraction of a second, where unattended information is rapidly lost.

Short-Term Store (STS)

A temporary storage component in the modal model containing auditory, linguistic, and verbal components, with an unmaintained duration of about 30 seconds.

Long-Term Store (LTS)

The permanent storage repository in the modal model, categorized into modalities (auditory, linguistic, visual, temporal, verbal), where forgetting occurs via decay, interference, or loss of strength.

Focus of Attention

The component in Cowan's activation model, often compared to a spotlight, that moves within the activated portion of long-term memory to consciously process information.

Duration of Short-Term Memory

The temporal limit of short-term memory in the absence of active maintenance rehearsal, documented to be approximately 30 seconds.

Capacity of Short-Term Memory (Miller, 1956)

The typical limit on the number of discrete units a person can hold in immediate memory across diverse stimuli, defined as $7 \pm 2$ items or chunks (5 to 9 items).

Chunking

The cognitive process of grouping individual pieces of information into larger, familiar, meaningful units to expand the functional capacity of short-term memory.

Primacy Effect

The tendency to exhibit superior recall for items presented at the beginning of a list, attributed to increased opportunity for rehearsal and transfer into long-term storage.

Recency Effect

The tendency to exhibit superior recall for items presented at the very end of a list in immediate free recall, which vanishes when a delay or distracting task is introduced.

Immediate Free Recall

A memory retrieval paradigm where participants recall as many list items as possible in any arbitrary order immediately following list presentation.

Verbal/Acoustic Code in STM

An internal representational format in short-term memory where items are maintained through subvocal speech, phonological properties, and internal repetition.

Word Length Effect (Baddeley, Thomson, & Buchanan, 1975)

The empirical finding that recall is significantly higher for lists of short words ($83\%$) than long words ($56\%$) because shorter words take less time to rehearse subvocally within a fixed retention interval.

Brown-Peterson Task

An experimental procedure developed by Brown (1958) and Peterson and Peterson (1959) where participants view a three-letter trigram and count backwards by threes during a retention interval to prevent rehearsal.

Trigram

A three-consonant letter sequence (such as ZBE) presented as the target stimulus in short-term memory decay tasks like the Brown-Peterson task.

Decay Theory

The hypothesis proposing that memory traces in short-term storage weaken, degrade, and are lost spontaneously solely due to the passage of time.

Interference Theory

The explanation of forgetting stating that memory loss occurs when retrieval is blocked or disrupted by competing information or concurrent mental processes.

Proactive Interference (PI)

A type of interference where older, previously learned information interferes with or blocks the learning and recall of newly presented information.

Retroactive Interference (RI)

A type of interference where newly encountered information impairs or blocks the retrieval of older, previously stored information.

Keppel and Underwood (1962) Reanalysis

A critical study demonstrating that performance on the Brown-Peterson task is near-perfect on the very first trial despite an 18-second delay, proving that forgetting is driven by the buildup of proactive interference across trials rather than simple decay.

Release from Proactive Interference (Wickens, 1973)

A dramatic rebound in short-term recall performance that occurs when the semantic category or topic of items is switched after several consecutive trials from the same category.

Working Memory (WM)

An active, dynamic memory system responsible for the simultaneous temporary storage, manipulation, and processing of immediate information.

Static Storage Architecture

The view characterizing classic short-term memory as a passive, fixed storage container that maintains items without processing or manipulating them.

Dynamic Memory Architecture

A view of immediate memory (such as working memory) that emphasizes active processing, flexible boundaries, resource coordination, and ongoing adaptation to task demands.

Phonological Loop

The slave subsystem of working memory specialized for maintaining simple verbal and acoustic speech-based information via subvocal repetition.

Visuo-Spatial Sketchpad

The slave subsystem of working memory responsible for holding and manipulating visual images and spatial coordinates in mind.

Central Executive

The core supervisory component of working memory responsible for directing activities, processing information, managing task switching, and allocating limited cognitive resources.

Episodic Buffer

A component in Baddeley's expanded working memory model that binds and integrates phonological, visual, spatial, and long-term memory representations into a coherent chronological sequence.

Cognitive Capacity / Resources

The finite supply of mental processing energy and attention available to an individual to divide among concurrent cognitive operations.

Acoustic Confusions (Conrad, 1964)

An experimental finding where participants presented with visual letter strings make recall errors based on sound similarity (e.g., substituting 'S' for 'F') rather than visual appearance (e.g., substituting 'E' for 'F').

Semantic Coding in Immediate Memory

The representation of items in working memory based on meaning and category membership, demonstrated by Wickens' findings on release from proactive interference.

Articulatory Suppression

A dual-task procedure where participants repeatedly vocalize irrelevant speech sounds (e.g., saying 'the, the, the') to occupy the phonological loop and prevent verbal rehearsal.

Dual-Task Paradigm (Baddeley & Hitch, 1974)

A methodology combining a primary sentence-verification reasoning task with concurrent secondary vocal suppression tasks to assess the functional independence of working memory components.

Baseline Reaction Time (Baddeley & Hitch, 1974)

The single-task control speed recorded when participants completed the primary reasoning task in isolation, measured at 2.79 seconds.

Automatic Concurrent Processing

The execution of well-learned secondary tasks (e.g., counting '1, 2, 3…' or repeating 'the, the, the') that run within the phonological loop without depleting central executive resources.

Controlled Concurrent Processing

The execution of demanding, unfamiliar secondary tasks (e.g., repeating a random six-digit sequence) that requires the central executive to redirect resources to the phonological loop, slowing performance.

Systematic Individual Variation

Stable, non-random differences between individuals across cognitive abilities and psychological traits, such as intelligence, personality, or working memory capacity.

Working Memory Capacity (WMC)

An individual difference metric reflecting a person's ability to maintain goal-relevant representations active in the face of concurrent processing, interference, and distraction.

Operation Span (OSPAN)

A complex span task assessing working memory capacity by requiring participants to verify mathematical equations while memorizing interspersed letters for subsequent serial recall.

N-back Task

A continuous working memory assessment task where participants track an ongoing stream of items and indicate when the current stimulus matches the one presented n steps earlier.

High-Span Individuals

Participants exhibiting high working memory capacity, characterized by superior attentional control, effective goal maintenance, and strong resistance to distraction.

Low-Span Individuals

Participants exhibiting low working memory capacity, characterized by susceptibility to distraction, weaker attentional control, and vulnerable task maintenance.

Kane and Engle (2001) Experiment

A study examining individual differences in working memory on the Stroop test by manipulating the proportion of congruent trials, revealing that low-span individuals struggle to inhibit dominant word-reading responses.

Cocktail Party Effect (Conway, Cowan, & Bunting, 2001)

The phenomenon of detecting one's own name in an unattended auditory stream during dichotic listening, demonstrated to occur substantially more often in low-span individuals due to lapses in attentional focus.

Sanchez and Wiley (2009) Experiment

An educational psychology study demonstrating that reading science texts on the causes of ice ages in a scrolling format selectively impaired text comprehension and essay performance for low-WMC readers.

Extraneous Cognitive Distraction

Non-essential perceptual or motor demands (such as web page scrolling) that disproportionately consume the limited cognitive capacity of low-WMC individuals, degrading higher-order learning.