AP® Psychology review sheet from Aim for Five (aimforfive.com/psych/units/2/2-4)
Unit 2 · Topic 2.4
2.4 Encoding Memories
Encoding is the process of getting information into memory, and how you encode something largely decides whether you'll be able to retrieve it later. Mnemonic devices, chunking, organizing into categories and hierarchies, and spacing out your study all improve encoding. The serial position effect shows that the order of information also matters.
Key terms
- encoding
- chunking
- mnemonic device (method of loci)
- spacing effect (distributed practice)
- serial position effect (primacy and recency)
What encoding is
Encoding is the first step of memory: converting information into a form your brain can store. Storage (2.5) is holding it over time, and retrieval (2.6) is getting it back out. Many 'memory failures' are really encoding failures: if you never paid attention to or processed something well, it was never stored to begin with.
How you encode matters as much as how much. Linking new material to its meaning, organizing it and connecting it to what you already know all create more pathways to that memory later.
Mnemonics and chunking
Mnemonic devices are memory aids. The method of loci asks you to picture a familiar place, like your house, and mentally 'place' each item to remember at a spot along a route. To recall, you take a mental walk and 'see' each item. Other mnemonics include acronyms (like ROY G BIV for the colors of the rainbow) and rhymes.
Chunking is grouping individual items into larger, meaningful units. The letters F B I C I A N B A are hard to hold as nine separate letters but easy as three chunks: FBI, CIA, NBA. Phone numbers are chunked into groups for the same reason.
Organizing information into categories or hierarchies, from broad ideas down to specific details, also helps. A list of 20 groceries is easier to recall if you group it into fruit, dairy and snacks. An outline of this unit is a hierarchy.
The spacing effect
The spacing effect is the finding that information studied in several sessions spread over time (distributed practice) is remembered better in the long run than the same amount of study crammed into one session (massed practice). Three 20-minute sessions on Monday, Wednesday and Friday beat a single 60-minute session Thursday night.
Cramming can work for tomorrow's quiz, but memories built through massed practice fade fast. Spacing gives the brain time to consolidate memories between sessions, and each new session makes you retrieve what you studied before, which strengthens it further (the testing effect, 2.6).
The serial position effect
When you learn a list, the position of each item affects how well you remember it. This is the serial position effect. Items at the beginning are remembered well (the primacy effect), likely because you had more time to rehearse them into long-term memory. Items at the end are remembered well too (the recency effect), likely because they're still in short-term memory when you're tested. Items in the middle are remembered worst.
Plotted as a graph, with list position on the x-axis and percent recalled on the y-axis, recall makes a U shape: high at the start, low in the middle, high at the end. If the test is delayed, the recency effect fades because those last items were never moved into long-term memory, while the primacy effect remains.
Worked examples
Try each one yourself first, then open the solution.
- Example 1
Interpreting serial position data
Participants hear a 15-word list. Group A recalls immediately; Group B recalls after 30 seconds of counting backward. Percent recalled for positions 1–3, 7–9 and 13–15: Group A, 70%, 30%, 75%; Group B, 68%, 28%, 32%. Explain the results.
Show the solutionHide the solution
- Step 1: Group A shows high recall at the start (70%) and end (75%) with a dip in the middle (30%). That U shape is the serial position effect, with both primacy and recency.
- Step 2: Group B keeps the primacy effect (68%) but loses the recency effect (32%).
- Step 3: Counting backward keeps participants from rehearsing and pushes the last words out of short-term memory. The first words had already been rehearsed into long-term memory, so they survive the delay.
- Step 4: This supports the idea that primacy depends on long-term memory and recency depends on short-term memory.
Answer: Both groups show primacy; only immediate recall shows recency, because the delay wiped out the last items held in short-term memory.
- Example 2
Recommending a study plan
Ethan has a biology test in one week and has 3 hours to study. He plans to study for all 3 hours the night before. Using encoding research, propose a better plan and justify it.
Show the solutionHide the solution
- Step 1: Name the concept: the spacing effect, which favors distributed practice over massed practice.
- Step 2: Propose a plan: split the 3 hours into six 30-minute sessions across the week.
- Step 3: Add encoding strategies: chunk related terms, organize them into a hierarchy (cells, then organelles, then functions) and use a mnemonic for a hard list.
- Step 4: Justify: spaced sessions give time for consolidation, and each session requires recalling earlier material, which strengthens memory more than one long cram.
Answer: Spread the 3 hours across the week (distributed practice) and organize the material with chunking, hierarchies and mnemonics; spacing leads to better long-term retention than massed practice.
Common mistakes
- Explaining the recency effect with long-term memory. Recency comes from items still being in short-term memory; that's why it disappears after a delay.
- Thinking distributed practice means studying more total time. The total can be the same; it's spreading it out that helps.
- Using 'chunking' for any memory trick. Chunking specifically means grouping items into larger meaningful units.
On the exam
- Expect graphs and data tables, especially serial position curves, and be ready to describe what the data show and why.
- Encoding strategies make good evidence for argument-style free-response answers about how students should study, so name the strategy and explain how it improves memory.
Connected topics
Videos
Check yourself
4 questions on 2.4 Encoding Memories. Pick an answer to see if you got it, and why.
Ava and Ben each study the same chapter for a total of four hours. Ava studies for one hour on each of four days, while Ben studies for four hours the night before the test. Which prediction about their memory one month later is best supported by memory research?
| Study instruction | Number of students | Mean items recalled the next day (out of 20) | Standard deviation |
|---|---|---|---|
| Repeat each item aloud until the list is finished | 30 | 8.1 | 2.4 |
| Make up a sentence connecting each item to the next | 30 | 12.6 | 2.9 |
| Picture each item at a spot along the route through your home | 30 | 15.2 | 2.6 |
Hypothetical experiment; students were randomly assigned to one of three study instructions for the same 20-item list
Which conclusion is best supported by the data?
The instruction that produced the highest recall is an example of
Asked to remember the digits 1 4 9 2 1 7 7 6, Leila remembers them as the years 1492 and 1776. Her strategy is an example of
0 of 4 answered