# FSRS-6 & Spaced Repetition — Ebbinghaus Forgetting Curve & Spacing Effect Fundamentals

> Foundational memory science covering Hermann Ebbinghaus's 1885 forgetting curve experiments, savings in relearning, the spacing effect vs. massed practice (cramming), Jost's Law, and Bjork's New Theory of Disuse.

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- **Markdown URL:** https://flashcards.world/flashcards/sets/914aa55d-08b6-4918-a3c3-8b160f695df6.md
- **Level:** basic
- **Languages:** en → en
- **Total Cards:** 32

## Flashcards (32 Cards)

| # | Front (Term / Prompt) | Back (Definition / Answer) | Example | Multiple-Choice Options |
| :--- | :--- | :--- | :--- | :--- |
| 1 | Why is a 'Power-Law Forgetting Curve' scientifically superior to an 'Exponential Forgetting Curve' for modeling human memory? | An exponential curve assumes a constant fractional hazard rate of forgetting over time, whereas empirical data (Wixted & Ebbesen, 1991; Rubin & Wenzel, 1996; FSRS) prove that the hazard rate of forgetting decreases as a memory ages—producing a heavy power-law tail. |  |  |
| 2 | Summarize the primary goal of any spaced repetition scheduler in one optimization statement. | Maximize long-term knowledge retention across a deck of cards while minimizing total cumulative review time by scheduling each review just before forgetting occurs. |  |  |
| 3 | What did Bahrick's 1979/1984 'Permastore' studies on long-term Spanish vocabulary retention reveal? | Knowledge acquired via distributed practice over multiple years reaches a near-permanent plateau ('permastore') that shows minimal decay over 25 to 50 years, whereas crammed knowledge decays rapidly after exams. |  |  |
| 4 | State Jost's First Law of Memory (Adolph Jost, 1897) regarding two memories of equal current retrievability. | If two memory associations are of equal current strength (retrievability) at the present moment, the older memory will decay more slowly over future time and benefit more from an additional repetition than the younger memory. |  |  |
| 5 | What is the 'Lag Effect' within spaced repetition research? | The finding that longer intervals (lags) between study sessions generally produce stronger long-term retention than shorter lags, up to the threshold where the memory trace is completely forgotten before the next review. |  |  |
| 6 | What is the 'Optimal Lag Ratio' (Cepeda et al., 2008) between the inter-study interval (ISI) and the retention interval (RI)? | In two-session experiments, the optimal gap between study sessions (ISI) is roughly 10% to 20% of the desired final test delay (RI), though multi-session FSRS schedules continuously expand intervals as Stability grows. |  |  |
| 7 | Why does massed practice (cramming) create a powerful 'Illusion of Competence' during a study session? | Because massed repetitions keep short-term Retrieval Strength near 100%, making recall feel effortless and fluent right now while producing minimal gains in long-term Storage Strength. |  |  |
| 8 | What is 'Encoding Variability Theory' as an explanation for the spacing effect? | When reviews are spaced across different days, your internal mental state and external context vary slightly at each exposure, binding the memory trace to richer, multiple retrieval cues rather than a single narrow cramming context. |  |  |
| 9 | How do Robert and Elizabeth Bjork's 'New Theory of Disuse' (1992) distinguish between the two independent strengths of a memory trace? | Every memory has (1) Storage Strength (how deeply and permanently entrenched the representation is in long-term memory) and (2) Retrieval Strength (how easily accessible the memory is at the current moment). |  |  |
| 10 | What is 'Study-Phase Retrieval Theory' (Remindings Theory) in spaced learning? | The principle that a spaced review works only if the learner successfully retrieves the prior learning episode during the second encounter, which reconsolidates and strengthens the original trace. |  |  |
| 11 | What is the difference between 'Fixed-Interval Spaced Repetition' and 'Adaptive Algorithmic Spaced Repetition'? | Fixed-interval schedules apply the same predetermined spacing gaps to every item, whereas adaptive algorithms (like SM-2 and FSRS-6) dynamically calculate individualized intervals for each card based on your personal review history and grade ratings. |  |  |
| 12 | What is 'Deficient Processing Theory' of massed practice? | When an item is repeated immediately while still active in working memory, the brain recognizes its high familiarity and devotes less attentional and synaptic processing effort to the repetition. |  |  |
| 13 | According to Bjork's New Theory of Disuse, how does current Retrieval Strength affect the gain in Storage Strength during a review? | Storage Strength gains are inversely related to current Retrieval Strength: when Retrieval Strength is high (e.g., massed cramming), little new Storage Strength is gained; when Retrieval Strength has decayed to a moderate level (e.g., spaced review at R ≈ 90%), successful retrieval produces a large jump in Storage Strength. |  |  |
| 14 | How does spaced repetition mitigate both proactive and retroactive interference? | By separating similar items across distinct temporal contexts and progressively widening intervals only as each item's distinct retrieval cue-target association stabilizes. |  |  |
| 15 | What is 'Metacognitive Calibration' in spaced repetition? | The accuracy with which a learner's subjective judgment of learning (JOL) matches their actual objective probability of recalling the item on a future delayed test. |  |  |
| 16 | What is 'Proactive Interference' in flashcard learning? | The phenomenon where previously learned similar information interferes with your ability to encode or retrieve newly learned information (e.g., confusing a newly learned Spanish verb with an older French cognate). |  |  |
| 17 | What is the core mathematical shape of the Ebbinghaus forgetting curve immediately after initial encoding? | Memory retention drops steeply during the first hours and days after initial learning, followed by a progressively flattening long-term tail that is best described mathematically by a power-law decay curve rather than a simple single-rate exponential. |  |  |
| 18 | In Hermann Ebbinghaus's memory experiments, how is the metric 'Savings in Relearning' mathematically defined? | Savings = (Original Learning Time − Relearning Time) / Original Learning Time × 100%, measuring the residual latent memory trace that persists even when conscious recall fails. |  |  |
| 19 | What is 'Retroactive Interference' in memory consolidation? | The phenomenon where newly acquired information disrupts or overwrites the consolidation and retrieval of previously learned memory traces. |  |  |
| 20 | Within declarative memory, how do 'Episodic Memory' and 'Semantic Memory' interact over repeated spaced reviews? | An initial flashcard encounter is often tied to an episodic context (when/where you first read it), which gradually transforms through spaced cortical consolidation into context-independent semantic knowledge. |  |  |
| 21 | What is the 'Spacing Effect' in cognitive psychology? | The robust empirical phenomenon whereby long-term memory retention is dramatically higher when study repetitions are distributed across time with intervening rest intervals rather than massed together in a single back-to-back session (cramming). |  |  |
| 22 | What did Paul Pimsleur's 1967 paper 'A Memory Schedule' propose for language learning intervals? | A graduated interval recall schedule in which learners are tested on new vocabulary at exponentially expanding intervals (e.g., 5 seconds, 25 seconds, 2 minutes, 10 minutes, 1 hour, 5 hours, 1 day, 5 days, 25 days, 4 months, 2 years). |  |  |
| 23 | What is the difference between 'Explicit (Declarative) Memory' and 'Implicit (Procedural) Memory' in relation to flashcards? | Explicit memory stores conscious facts and concepts (semantic and episodic memory, the primary target of flashcards), whereas implicit memory governs motor and procedural skills. |  |  |
| 24 | How does the 'Retrieval Effort Hypothesis' explain why harder successful recalls produce larger memory gains? | Within limits where retrieval still succeeds, greater cognitive effort during recall recruits deeper prefrontal-hippocampal engagement and triggers stronger synaptic reconsolidation than effortless recall. |  |  |
| 25 | In Roediger and Karpicke's landmark 2006 experiment comparing 4 study sessions (SSSS) vs. 1 study + 3 test sessions (STTT), what happened on a 5-minute test vs. a 1-week delayed test? | Cramming (SSSS) produced slightly higher recall after 5 minutes (81% vs. 75%), but active retrieval practice (STTT) dramatically outperformed re-reading after 1 week (56% vs. 42%), proving that retrieval effort halts rapid forgetting. |  |  |
| 26 | What happens if a review interval is stretched so far that Retrievability drops near 0%? | Retrieval fails completely (a lapse), forfeiting the testing effect and requiring full re-encoding time—which is why FSRS-6 targets a sweet-spot Desired Retention around 90% rather than 30%. |  |  |
| 27 | What does it mean that the hazard rate of forgetting decreases over time in a power-law memory model? | The longer a memory trace has already survived without being forgotten, the lower its instantaneous probability of being forgotten on the very next day— directly matching Jost's First Law. |  |  |
| 28 | What is the difference between 'Free Recall', 'Cued Recall', and 'Recognition' in memory testing? | Free recall retrieves information without prompts (hardest); cued recall retrieves a target in response to a specific prompt (standard flashcard Q&A); recognition identifies the correct answer among options (multiple choice). |  |  |
| 29 | What is the 'Foresight Bias' (Koriat & Bjork, 2005) when creating or reviewing flashcards? | Because the answer is visible or freshly activated during study, learners overestimate how easily they will recall the target in the future when the answer is absent and misleading cues are present. |  |  |
| 30 | Why does practicing with 'Cued Recall' (standard flashcards) transfer well to 'Recognition' (multiple-choice exams), but not vice versa? | Cued recall forces complete reconstruction of the memory trace from the prompt alone, building strong retrieval pathways that easily handle recognition distractors, whereas recognition practice can rely on superficial familiarity. |  |  |
| 31 | Who conducted the first rigorous experimental study of human forgetting and spacing in 1885, and what stimuli did he invent to eliminate prior semantic associations? | Hermann Ebbinghaus (published in 'Über das Gedächtnis', 1885), who invented consonant-vowel-consonant (CVC) nonsense syllables (e.g., WID, ZOF, KAX) to measure pure memory formation and decay without prior meaning. |  |  |
| 32 | In cognitive psychology, what is the 'Testing Effect' (or Retrieval Practice Effect)? | The finding (demonstrated by Roediger & Karpicke, 2006) that actively retrieving information from memory strengthens future retention and slows the rate of forgetting far more effectively than spending the same amount of time re-reading the material. |  |  |

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Study this deck interactively with FSRS-6 spaced repetition, audio review, and multiple-choice mode at [Flashcards World](https://flashcards.world/flashcards/sets/914aa55d-08b6-4918-a3c3-8b160f695df6/).