Obsidian Spaced Repetition

The Obsidian Spaced Repetition plugin allows you to fight the forgetting curve by reviewing flashcards and notes directly within Obsidian.md.

Core Capabilities:

• Flashcards: Create and review individual flashcards using specific syntax (e.g., :: to separate questions and answers).
• Notes: Review entire notes as part of a spaced repetition schedule.
• Deck Management: Organize cards and notes into decks using Obsidian tags (e.g., #flashcards/science/physics).
• Scheduling: The plugin uses repetition algorithms to determine when you should review specific content.
• Data Storage: Scheduling information is stored within the markdown files themselves using HTML comments, ensuring your data stays with your notes.

When working with Cloze cards, keep these two rules in mind:

1. No Mixing Types: You cannot mix different Cloze Types (e.g., Simplified and Classic) in the same note. They use different logic for sorting and identifying cards.
2. Pattern Conflicts: When creating custom patterns, ensure they do not conflict with existing separators. For example, the Anki-like pattern {{[123::]answer[::hint]}} conflicts with the default single-line flashcard separator ::.

The plugin persists configuration and certain runtime data in a file named data.json located within the plugin folder:

• User Options: All settings configured via the plugin options menu.
• Card Postponement List: A list of numeric hash codes ("fingerprints") representing cards reviewed today that have sibling cards buried until tomorrow. This list is only populated if the Bury sibling cards until the next day setting is enabled.

To maximize the effectiveness of spaced repetition within Obsidian, follow these principles for note creation:

• Atomicity: Notes should be atomic, focusing on a single concept.
• Linking: Notes should be highly linked to other concepts in your vault.
• Understanding: Do not start reviewing a note until you have a proper understanding of the concept.
• Feynman Technique: Reviews should be approached using the Feynman technique (explaining a concept in simple terms to ensure deep understanding).

The plugin uses two primary methods for storing scheduling data, though the 'Individual Markdown Files' method is the current standard:

1. For Cards: Scheduling data is stored in an HTML comment immediately following the card text. By default, this is on the line following the card. You can enable the Save scheduling comment on the same line as the flashcard's last line? option to keep it on the same line. Example comment format: <!--SR:!YYYY-MM-DD,ease,interval-->

2. For Notes: Scheduling data is stored in the YAML frontmatter at the beginning of the Markdown file using specific keys.

Note: A 'Single Scheduling File' implementation is currently a planned feature and is not yet available.

<!--SR:!2024-08-16,51,230-->

---
sr-due: 2024-07-01
sr-interval: 3
sr-ease: 269
---

The plugin provides two distinct modes for interacting with flashcards:

1. Reviewing: Focuses on spaced repetition. It only shows new cards (never reviewed) and due cards (cards the algorithm has scheduled for review).
2. Cramming: Focuses on intensive study. It shows every single card in the selected deck or note, regardless of when they were last reviewed.

The plugin supports two primary flashcard formats defined within standard Obsidian markdown files:

1. Question & Answer: The flashcard text contains both the question and the answer.
2. Cloze: The flashcard text identifies specific parts (words or phrases) to be hidden. These hidden parts are called cloze deletions. When the front of the card is shown, the deletions are hidden.

Note: A markdown file must identify a deck to contain flashcards, but the file does not need to be tagged as a note.

The status bar at the bottom of the Obsidian interface contains the Spaced Repetition Status Area. It displays a summary in the format Review: N note(s), where N is the total number of notes to review today (including both today's scheduled notes and overdue notes).

Clicking this area will automatically open one of your notes for review.

The SM-2-OSR algorithm updates the interval and ease based on the user's review rating:

Constraints & Details:

• Minimum Ease: The minimum ease value is 130.
• Link Contribution: The initial ease calculation uses link_contribution = max_link_factor * min(1.0, log(link_count + 0.5) / log(64)) to account for uncertainty in linked concepts.

The SM-2-OSR algorithm is the currently implemented scheduling formula. It is a variant of Anki's SM-2 algorithm and supports ternary reviews: hard, good, or easy.

Key characteristics include:

• Weighted Initial Ease: The initial ease of a note is calculated using a max_link_factor based on the average ease of linked notes, note importance (determined via PageRank), and a base ease.
• Fuzzing: For intervals of 8 days or more, a small amount of random "fuzz" (up to 5% of the interval) is added or subtracted to prevent multiple cards from clustering on the same review day.
• Storage: Scheduling data is stored directly in the note's YAML front matter.

Incremental Writing is a method of managing a 'writing inbox' using spaced repetition. Instead of traditional flashcards, you review notes to decide how to evolve them.

When reviewing notes in this workflow, you typically perform one of four actions (where x < y represents intervals):

1. Skip note: Increase the interval for x (equivalent to marking as good).
2. Work on it (fruitful): Decrease the interval (equivalent to marking as hard).
3. Work on it (unfruitful): Increase the interval for y (equivalent to marking as easy).
4. Convert to evergreen note: Stop using spaced repetition prompts for this note entirely.

If a parent note has headings, the flashcard title can display the heading hierarchy as context (e.g., Trivia > Capitals > Africa).

To enable this, you must enable the context setting in UI Preferences within the plugin settings.