Back to the on-screen lesson ·
The small, leaky space where something is kept while it is used, what the research says about how much and how long, and a load count to spot which limit a task hits.
Paper packet. Every task here also exists on screen, where it is checked automatically; answers written on paper are not assessed by Nydus. When you are back at a device, enter your answers there.
You will say what working memory is, count the separate pieces a task asks you to hold, tell a size problem from a leak, read a record of how fast unrepeated items fade, and try one optional span trial.
You have almost certainly done this. Someone reads you a number. You walk to the phone saying it over. On the way, someone asks you a question. By the time you pick up the phone, half the number is gone.
Nothing went wrong with you. This lesson explains what happened, in plain terms, and gives you one small tool: a way to count how much a task is asking you to hold. The rest of the course is about arranging things so that it asks for less.
| Term | What it means |
|---|---|
| Working memory | The small space where you keep something while you are using it. |
| Long-term memory | The large store of everything you know, from words to faces to routes. |
| Rehearsal | Saying something over, silently or aloud, to keep it in mind. |
| Chunk | A group that counts as one piece because you already know it, like 1776 or FBI. |
| Load count | A list of the separate pieces a task asks you to hold at the same time. |
| Span | The longest string someone repeats back correctly on one trial. It changes from trial to trial. |
Think of two places. Long-term memory is a warehouse. It is huge, it fills slowly, and it holds everything you know. Working memory is the desk where you lay out what you are using right now: a number to dial, the running total of a sum, the next step of a recipe.
The desk has two limits, and it helps to keep them apart.
It is small. It holds only a handful of separate things. Past that, something slides off the edge.
It is leaky. A piece stays on the desk only while you keep touching it, by saying it over or using it. When something else takes the desk — a question, a conversation, a new sum — the untouched piece fades within seconds.
Neither limit is a flaw in anyone. They are how everybody's desk works. So when a task goes wrong because of them, the useful response is to change the task, not to blame the person doing it.
Another way: diagram
Picture a desk with room for about four cards. Each separate thing you hold is a card. Add a fifth and one slides off. Stop touching a card and it fades. Two ways out: glue cards together into one (a chunk), or pin a card to the wall (write it down).
Another way: story
Andre hears the plumber's ten-digit number and says it over as he walks down the hall. His daughter asks what is for dinner, and he answers. At the phone, three digits are left. Ten digits was already a crowded desk, and the dinner question stopped the repeating. Both limits struck at once.
In 1956 the psychologist George Miller summarized studies of how many digits or letters people could repeat back. His famous answer was seven, plus or minus two.
Later work changed the picture. Nelson Cowan reviewed many studies (2001, and a shorter summary in 2010). He argued that Miller's seven includes help from two tricks: grouping items into chunks, and saying them over. When experiments block both tricks, people hold about three to five chunks, and Cowan's usual shorthand is about four.
So this course uses four as a rough guide. It is not a rule for any one person on any one day. Sleep, noise, worry and illness all move it. It is a reminder that the desk is smaller than it feels.
In 1959 Lloyd and Margaret Peterson showed people three consonants, such as K, B, T. Straight away they had to count backward by threes from a number, which stopped them repeating the letters. After 3 seconds, most people still had the letters. After 18 seconds, they recalled them correctly on only about one trial in ten.
Three letters is a small load, well under four. The loss came from the leak, not the size. Take the repeating away and a small load still fades fast.
In the 1970s Alan Baddeley and Graham Hitch gave the desk the name working memory. Their model has one part that holds sounds and words, one that holds images and places, and a controller that shares attention between them.
Before a task, or after one went wrong, do a load count:
To check your count, say each piece aloud as you touch a finger. If you run out of one hand, the task is asking for more than the desk holds.
A US phone number such as 312-555-0147 is ten digits. Read as ten separate digits, it is well past four pieces. The dashes split it into an area code, a three-digit exchange and a four-digit line number.
If you already know the area code — 312 for Chicago, say — that part costs one piece, not three. Many people hold the rest by saying it in its two groups. The count drops from ten to about three or four, which is why the grouping has stayed in use for decades.
The leak still applies. Hold the number while someone talks to you and it can fade. That is why phones offer to save the number of a missed call: the phone takes the card off your desk entirely.
A server takes an order for a table of four: two burgers, one medium and one well done; a salad with no onions; soup of the day. Counted piece by piece, that is at least seven: two burgers, two cooking levels, a salad, a change, a soup. Seven is more than four.
That is why most restaurants give servers a pad or a handheld screen. Servers who do go without one lean on their long-term memory of the menu and on fixed habits, such as always taking orders clockwise from the same seat. Those habits turn many loose pieces into a few known ones. The desk is the same size.
A good memory holds everything, if you try. Trying hard helps in one narrow way: it keeps you repeating. It does not make the desk bigger. Ten unrelated digits is more than it holds, for nearly everyone, however motivated.
Losing a number means my memory is failing. Losing an unwritten number after an interruption is the expected result for anyone. It says something about the task, not about you. The cure is usually a pen.
The limit is the same as a lack of knowledge. You can know a great deal and still have a small desk. The warehouse and the desk are different places.
List what must be held at once.
Voicemail: call Dana back at 617-555-0183 before 4:30 about the Tuesday delivery.
Everything you would need to act without replaying the message.
Count the separate pieces.
10 digits + Dana + 4:30 + Tuesday delivery = 13 pieces
An unfamiliar number counts one piece per digit.
Compare the count with about four.
13 is more than 4
Four is the rough guide from Cowan's review.
Check the leak.
Nothing stops the repeating yet, but the message is heard once.
The size alone is enough to lose pieces.
Name the limit and change the task.
Limit: size. Change: replay the message with a pen and write it down.
When the count is far over four, writing is the fix.
List what must be held at once.
Parking garage: level 3, row G.
Two things tell you where the car is.
Count the separate pieces.
3 + G = 2 pieces
Each part of the location is one piece.
Compare the count with about four.
2 is fewer than 4
Size is not the problem here.
Check the leak.
A phone call starts at the elevator and lasts four minutes.
Talking takes the desk, so the repeating stops.
Name the limit and change the task.
Limit: leak. Change: take a photo of the level sign before the call.
The Petersons' letters faded in 18 seconds; four minutes is far longer.
List what must be held at once.
Airport announcement: flight 2291 now boards at gate B14 at 6:05.
Everything needed to get to the right gate on time.
Count the separate pieces.
4 digits of the flight + B14 + 6:05 = 6 pieces
B14 and 6:05 are each one known unit here; the flight number is four separate digits.
Compare with four and name the limit.
A friend reads you a 10-digit number in one breath. You have no pen and cannot ask them to repeat it. What is the most likely outcome?
A load count for a pizza order taken by phone is half done. The order: one large pepperoni, one medium veggie with no olives, and two sodas, for pickup at 7:15. Fill in the later rows.
| Load count | |
|---|---|
| Pieces listed | large, pepperoni, medium, veggie, no olives, 2 sodas, 7:15 |
| Count | 7 |
| Compare | |
| Limit | |
| Change |
Put these in order from the fewest separate pieces to hold in mind to the most. Nothing may be written down.
Number the steps in order (write the number in the box):
In a classroom version of the Petersons' task, three letters were shown and then everyone counted backward by threes, so nobody could repeat the letters. Over 20 trials, the letters were recalled correctly 15 times after 3 seconds and 4 times after 18 seconds. What percentage of trials were correct after 18 seconds?
Answer:
Optional span practice. Six digits appear for ten seconds. Then write them back in the order you saw them, one per box. This is practice of one task, not a test of your memory, and you can skip it.
Ask someone to read you the list, then cover it and write what you remember:
Four everyday slips. For each, name the limit that caused it: size (too many pieces) or leak (repeating was stopped).
| Slip | Limit |
|---|---|
| A 12-character Wi-Fi password read off a card once | |
| Hotel room 214, forgotten after chatting in the elevator | |
| Eight grocery items asked for at the door, no list | |
| A new neighbor's first and last name, gone while talking about parking |
Lesson test: one question per skill, one attempt each, no hints. Your answers are checked when you submit.
For each task, write how many separate pieces it asks you to hold, and whether that is about four or fewer, or more than four.
| Task | Pieces | Compared with four |
|---|---|---|
| A new 5-digit gate code, heard once | ||
| The zip code you live in | ||
| Three errands: bank, post office, pharmacy |
Without looking back: roughly how many chunks does the desk hold, and what happens to an item nobody is repeating? Say both aloud, then check. Next: making the pieces bigger by grouping them. A trial in this course is practice. What is kept is what you wrote on this device today; it is not a score, it is not a test of your memory, and it is never compared with anyone. If you notice trouble with memory or thinking that is new or changing, tell your own doctor or clinician; this course is general practice, not an assessment or treatment. Stopping takes nothing more than closing the page: your place is already saved, and the lesson opens where you left it.
13. Your turn: a load count on a gate change, step 3
6 is more than 4. Limit: size. Change: check the screen or the app.
Over four pieces, heard once, is a size problem.