Notes on the Information Processing Model, Sensory/Short-Term/Long-Term Memory, and Working Memory

Encoding, Storage, Retrieval (Information Processing Model)

• Information processing model (also called the modal model) describes how memory works in three stages: encoding, storage, retrieval.
• Retrieval failures can occur at any stage (e.g., not remembering a name you just heard, later remembering it: the classic tip-of-the-tongue phenomenon).
• Analogy: computer mind and memory pipeline. Information enters via encoding, is stored, and later retrieved. Errors can happen at each step (e.g., losing a slip of paper, misplacing a password, failing to locate a saved Word document).
• The model emphasizes a flow: sensory memory -> short-term memory -> long-term memory, with the possibility to fail or fail to transfer between stages.
• Historical note: Norman & Waugh proposed the information processing/modal model in 1965; Atkins & Schiffrin proposed a very similar model in 1968. Despite similar ideas, the name most people cite comes from Atkins & Schiffrin (longer tradition of calling it the modal model).
• Encoding is the process by which information enters the memory system (attention and neural activity). If encoding is shallow or incomplete, later retrieval will be harder.
• Storage (short-term and long-term) is about preserving information for future recall.
• Retrieval involves bringing stored information back into conscious awareness when needed.
• Everyday implications: awareness of where memory failures occur helps design study strategies (e.g., encoding strategies, organization, cues).
• The narrative example with a scholarship code illustrates encoding, storage, and retrieval:
  • Encoding: hearing the code and writing it down.
  • Storage: keeping the note in a wallet, hand, or locked box.
  • Retrieval: later needing to retrieve the code for registration.
  • Potential errors: paper gets lost (retrieval failure), misfiled, or not recalled when needed.
• The model implies distinct memory stores and processes, which is important for understanding learning, study strategies, and cognitive-load management.
• Related concepts: attention (critical for encoding), rehearsal (helps transfer to long-term memory), and the idea that memory is not a perfect recording; it is reconstructive and subject to errors.

Sensory Memory

• Sensory memory holds raw sensory information briefly before it is encoded into short-term memory.
• Durations:
  • Sensory memory is very short-lived, typically around $1 ext{-}4 ext{ seconds}$ depending on modality (iconic vs. echoic).
• Types:
  • Iconic memory: visual information; a fleeting visual trace remains briefly after a stimulus is removed.
  • Echoic memory: auditory information; auditory traces persist slightly longer than iconic memory.
• Automatic and unconscious:
  • Sensory memory operates without conscious control; you don’t have to try to remember it—it’s just there for a brief moment.
• Iconic memory details:
  • After showing an image briefly and removing it, a short-lasting trace remains; you can recall approximate features even without trying.
  • Sperling’s iconic memory research demonstrated this with a grid paradigm and partial report procedures (below).
• Echoic memory details:
  • Auditory traces stay in memory briefly, enabling comprehension of spoken language even if you momentarily miss part of a sentence.
• Sperling’s grid experiment (iconic memory):
  • A grid of 12 items (3 rows x 4 columns) shown briefly; participants asked to recall as many items as possible.
  • Full report (recalling all 12 items) yields relatively low accuracy; partial report improves performance dramatically.
  • Partial report procedure: after showing the grid, cue the participant to report a specific row (top/middle/bottom). This typically yields much higher accuracy for the cued row, suggesting the sensory trace was available for the whole grid but faded quickly unless attended to.
• Key takeaway: iconic memory lasts only a short time (roughly $0.5 ext{-}1.0 ext{ seconds}$, sometimes up to $1 ext{-}2 ext{ seconds}$ depending on the method), and you can retain a highly accurate “snippet” briefly if cued correctly (partial report).
• Eidetic imagery (photographic memory): a rare phenomenon where some individuals can recall detailed visual information after a brief exposure. An example discussed: Mary Lou Henner (referenced in transcript as Mary Lou Inner) as a famous case. These are exceptional and rare; not representative of typical memory.

Short-Term Memory (STM) and Its Limits

• STM is the intermediate storage where information can be held temporarily and manipulated; it acts as an interface between sensory memory and long-term memory.
• Duration: STM lasts only briefly unless actively maintained; without rehearsal, information fades quickly.
• Brown–Peterson paradigm (1959): classic method to measure STM duration when rehearsal is prevented.
  • Task: memorize a set of consonants (e.g., JLP) and a 3-digit number; then perform a distractor task (count backwards by threes) for a variable duration (3, 6, 9, 12, 15, 18 seconds).
  • After the distractor, recall the consonants.
  • Findings show rapid decay of information from STM if not rehearsed or transferred to LTM:
  • Approximately $80 ext{-}90 ext{?}$% correct at 3 seconds,
  • ≈ $60 ext{-}60 ext{?}$% at 6 seconds,
  • ≈ 35 ext{%} at 9 seconds,
  • ≈ 25 ext{%} at 12 seconds,
  • ≈ 10 ext{%} at 15 seconds,
  • ≈ 10 ext{%} at 18 seconds.
  • The key conclusion: without rehearsal, short-term memory decays extremely quickly; maintenance rehearsal is needed to keep items in STM or to transfer to LTM.
• STM capacity and Miller’s Magic Number:
  • On average, people can hold about $7 ext{ units} ext{ (plus/minus } 2 ext{)}$ in STM: $7 ext{ } ext{±} ext{2}$
  • This implies a typical capacity around $5 ext{–}9$ items, depending on the person and the information type.
• Chunking as a strategy to extend STM capacity:
  • Group meaningful items into larger, semantically cohesive units.
  • Example: turning a long string of digits into dates or familiar sequences (e.g., historical dates such as 1836, 1861, 1940, 1914, 1941, 09/11, etc.).
  • By chunking, you can treat a sequence of digits as fewer, meaningful units, effectively expanding usable STM capacity beyond $7 ext{ units}$ when those units are meaningful to the learner.
• Duration and the role of rehearsal:
  • Maintenance rehearsal (repeating or subvocalizing information) helps keep items in STM temporarily, but is less effective for long-term retention unless the material is encoded into LTM.
  • Rehearsal is most effective when it is used to create connections to prior knowledge or to create multimodal encodings (e.g., dual coding).
• Rehearsal, encoding, and the forgetting curve:
  • The forgetting curve (classic study by Ebbinghaus, referenced in class as related to forgetting in the long-term memory discussion) shows how memory decays over time if not reinforced or integrated with existing knowledge.
  • In classroom contexts, last-minute cramming relies on STM and short-term rehearsal; without strategies to transfer to LTM, information is prone to rapid decay before the exam.

Working Memory (Bradley & Hicks 1974) and the Four-Component Model

• Working memory vs short-term memory:
  • Working memory is not just a passive store; it is an active processing system that both maintains and manipulates information held in memory for use in complex tasks (planning, problem solving, decision making).
  • The term “working memory” emphasizes active processing and manipulation, not merely storage.
• Four main components of the working memory system (Bradley & Hicks, 1974):
  • Phonological loop: rehearsal and manipulation of auditory/verbal information (e.g., subvocal rehearsal of numbers like $867 ext{-}5309$ during encoding or maintenance).
  • Visuospatial sketch pad: maintenance and manipulation of visual/spatial information (mental imagery, spatial relations, etc.).
  • Central executive: the “boss” that directs attention, coordinates the subcomponents, and manages cognitive control (planning, decision making, task switching, filtering irrelevant information).
  • Episodic buffer: a temporary storage system that combines information from multiple sources (phonological loop, visuospatial sketch pad, long-term memory) and can reflect information into long-term memory; acts as a backup/resource buffer when the other components need extra capacity.
• Central executive as the driver of attention and cognitive control:
  • Directs attention to relevant information and away from irrelevant information.
  • Plays a critical role in divided attention tasks and in determining information that is included in attention and working memory for ongoing processing.
  • Strongly linked to individual differences in attention, fluid intelligence, reading comprehension, and verbal ability.
• Long-term memory connections:
  • Working memory interacts with long-term memory; information can be retrieved from LTM into WM for current processing, and information generated in WM can be encoded into LTM for later retrieval.
  • The episodic buffer helps bridge WM and LTM by keeping integrated representations temporarily before consolidation.
• The executive model and computer metaphor:
  • Baddeley & Hitch described WM as a “multipurpose processor capable of running many different operations on many different types of material.” analogous to a computer operating system coordinating tasks.
  • The central executive functions as the control unit, while the subsystems are like specialized processors (verbal, visual/spatial) responding to task demands.
• Practical implications of WM:
  • Working memory capacity constrains everyday cognitive tasks (problem solving, planning, mathematics, reading comprehension).
  • Improvements in working memory are associated with broad cognitive benefits (goal setting, study planning, etc.).
  • In education, strategies that reduce cognitive load and leverage chunking, dual coding, and rehearsal can support WM functioning and learning.

The Four Components in Action and Integration with Learning

• Phonological loop in action:
  • Rehearsal of verbal information (e.g., repeating numbers or words in head when studying or solving a problem).
  • Subvocalization (silent speech) is a common rehearsal mechanism used to maintain information verbally.
• Visuospatial sketch pad in action:
  • Maintains mental images and spatial relations; useful when solving geometry, visualizing processes, or recalling maps or diagrams.
• Central executive in action:
  • Orchestrates attention, task switching, and planning.
  • Important for executive functions like planning a study schedule, prioritizing tasks, and managing distractions.
• Episodic buffer in action:
  • Holds integrated representations and serves as a buffer for temporary storage when the other subsystems are overloaded or when bridging to LTM.
• Interaction with attention and perception:
  • Attention modulates what gets into WM; the central executive can override or suppress information based on relevance and task goals.
  • The manager of the system (central executive) determines what is attended to and what is ignored, shaping what gets encoded into LTM.

Practical Implications and Real-World Relevance

• Memory coaching and study strategies:
  • Use chunking to expand STM capacity by forming meaningful units.
  • Use dual coding (auditory + visual) to strengthen encoding (e.g., reading notes aloud while viewing diagrams).
  • Employ maintenance rehearsal to preserve information temporarily; combine with elaborative rehearsal to connect new material to prior knowledge for LTM transfer.
  • Design study tasks that require active manipulation of information (e.g., reorder data, compare and contrast, timeline construction) to engage the central executive and enhance WM functioning.
• Eyewitness memory and reliability (briefly referenced):
  • Long-term memory and eyewitness memory can be fallible; the interplay between WM and LTM is critical in how memories are formed and recalled in real-world settings.
  • These topics lead to important ethical and practical considerations in law, education, and policy (e.g., the reliability of memory under stress, the impact of suggestion, and the malleability of memory over time).
• Real-world examples from the transcript:
  • Forgetting a name: retrieval failure due to encoding/retrieval mismatch.
  • The “scholarship code” exercise illustrates encoding (hearing and writing), storage (where to put the note), and retrieval (needing the code later) with multiple potential failure points (lost note, misfiled, or overwritten by newer information).
  • The lockbox, wallet, hand, note in a folder metaphors show different storage strategies and their vulnerability to forgetting or loss.
• Limitations and scope:
  • The modal model has been refined by later theories (e.g., working memory model) to reflect active processing, not just static stores.
  • The speaker notes that long-term memory and eyewitness memory involve additional processes not fully covered in the current segment; those topics are reserved for later discussion.

Key Experimental Evidence and Figures Mentioned

• Norman & Waugh (1965) and Atkins & Schiffrin (1968): proposed the information processing/modal model.
• Sperling’s iconic memory experiments (iconic memory evidence):
  • Grid experiments (3x4 grid) and partial report procedures demonstrated that a large amount of visual information is briefly held in a sensory register, even if not all of it is consciously reported.
• George Miller (1950s): classic finding of short-term memory capacity around $7 ext{ units} ext{ (plus/minus } 2 ext{)}$, i.e., $7 ext{ } ext{±} ext{2}$ items.
• Brown & Peterson (1959): foundational paradigm for short-term memory duration with distractor tasks; showed rapid decay of information from STM without rehearsal or transfer to LTM.
• Baddeley & Hitch (working memory model, 1974): proposed the four-component WM model (phonological loop, visuospatial sketch pad, central executive, episodic buffer) and argued WM is a separate system from STM.
• Lily notes on dual coding and attention: auditory and visual encoding together can boost retention and recall; attention (central executive) is a key determinant of what gets encoded and retained.

Connections to Foundational Principles and Real-World Relevance

• The memory system is organized and modular, with distinct stores and processing components that interact to support learning, problem solving, and decision making.
• Attention and encoding are critical bottlenecks: if information isn’t attended to or encoded effectively, it will be harder to retrieve later.
• Active maintenance and manipulation (working memory) underpin most higher-order cognitive tasks: planning, reading comprehension, math, reasoning, and decision making.
• Practical strategies (chunking, repetition, dual coding, meaningful encoding) leverage the architecture of memory to improve learning efficiency and exam performance.
• Understanding memory errors helps in designing better educational tools, user interfaces, legal procedures (eyewitness memory), and daily strategies to minimize forgetting.

Formulas and Key Numerical References (LaTeX)

• Miller’s magic number (capacity of STM): $7 \pm 2$
• Short-term memory duration estimates: $1\text{-}4\ \text{s}$ for sensory memory; STM typical duration without rehearsal on the order of seconds (Brown-Peterson paradigm shows rapid decay times from 3 to 18 seconds depending on rehearsal and interference).
• Brown–Peterson task structure: memorize consonants (e.g., $J L P$) and a 3-digit number, then count backwards by threes for variable duration before recall.
• Short-term memory test durations and recall percentages (from Brown & Peterson): approx. at 3 s: $\approx 80\%$, at 6 s: $\approx 60\%$, at 9 s: $\approx 35\%$, at 12 s: $\approx 25\%$, at 15 s: $\approx 10\%$, at 18 s: $\approx 10\%$
• Grid in Sperling’s iconic memory task: a 3 × 4 grid (12 items); recall performance often improves under partial report conditions, suggesting a rich but fleeting sensory trace.
• Visual and auditory memory durations: iconic memory about $0.5 ext{-}1.0 \text{s}$ (some data indicate up to $1 ext{-}2 \text{s}$ depending on method); echoic memory lasts slightly longer than iconic, on the order of a few seconds.
• Chunking example: turning long digit strings into meaningful units (e.g., dates, event numbers) to reduce the number of units to recall; illustrates that chunk size and meaningfulness expand usable WM capacity beyond $7\pm2$ units.
• Phonological loop and subvocal rehearsal: internal rehearsal helps maintain verbal information; central executive coordinates the use of these components during tasks requiring manipulation of information.

References to People and Studies Mentioned

• Norman, D. A., & Waugh, C. (1965) – original modal model proposal
• Atkinson, R. C., & Shiffrin, R. M. (1968) – modal model refinement and naming of long-term vs short-term memory
• George Sperling – iconic memory experimental paradigm (grid and partial report procedures)
• Brown, J. (1959) and Peterson, P. & Peterson, M. (1959) – short-term memory duration and decay
• Baddeley, A. D., & Hitch, G. J. (1974) – working memory model with four components
• Mary Lou Henner (as a famous eidetic memory case example; rare phenomenon of perfect visual memory)

Quick Takeaways for Exam Prep

• Memory is not a perfect recording; it is a series of processes with potential failures at encoding, storage, and retrieval.
• The modal model posits a flow: sensory memory (very brief) → short-term memory (brief, capacity-limited, requires rehearsal) → long-term memory (durable storage) with possible transfer from WM via elaborative processes.
• Sensory memory shows large quantities of information briefly; iconic memory is the visual component; partial report reveals the richness of the stored trace despite limited conscious reporting.
• Short-term memory capacity is limited (~$7\pm2$ items) but can be expanded via chunking and meaningful encoding; duration without rehearsal is brief (Brown–Peterson paradigm).
• Working memory adds active processing: phonological loop, visuospatial sketchpad, central executive, episodic buffer. It is critical for higher-order cognition and correlates with fluid intelligence and reading comprehension.
• Practical study strategies should emphasize encoding, rehearsal, chunking, and engaging both verbal and visual channels to enhance retention and transfer to LTM.