List-length effect
Memory effect
The longer a list is, the smaller the share of its items we remember, even though we may recall a few more items in total.
In everyday life
Asked to pick up 5 things at the store, you remember all of them, but asked for 25, you come home with a few more items and most of the list forgotten.
Your manager names three tasks and you remember every one, but when she names fifteen the next day, you walk away able to recall only a small fraction of them.
Why your mind does this
We cannot hold every moment of an experience or every item in a list in mind. The brain keeps a few standout pieces, such as the most intense moment, the ending, or the first and last items, and lets them stand for the whole. This makes memories compact and quick to use.
Its family, in 30 seconds: Key elements
How to spot it
Notice when someone hands you a long string of items and you feel sure you will remember them all.
What you can do
Keep spoken lists short, or write them down as soon as they grow beyond a handful of items.
Same family: Key elements
SourcesMurdock (1962)·Wikipedia