When you know something, is that different from remembering? Both types of thoughts are clearly part of the memory system, but is there really any difference between the two concepts? We often use the two terms nearly interchangeably: I might say “I remember Suzanne had her purse when we left the restaurant because I saw her pull out her phone at the bus stop,” but I might equally say “I know Suzanne had her purse on the bus because she was gabbing on the phone the whole ride home.”
But the subtle linguistic difference between the two terms isn’t meaningless. We might know George W. Bush is President, but if we remember that James Garfield was the President who preceded Chester A. Arthur, it’s likely due to a specific recollection from 11th grade history class (either that or we attended Garfield High School).
We say that we know something because of a general sense that it is true, but we remember something because we recall a particular incident. Psychologists have actually been able to measure the distinction between the two, simply by asking test subjects whether they know or remember the answer to a question (and explaining what they mean by the two terms).
So how does a “know” memory get formed? Are there circumstances when we’re more likely to form a “remember” memory? Can one sort of memory transform into the other? Or is the difference between know and remember simply an artifact of the fact that we remember some things better than others? A team led by John Gardiner had volunteers listen to a set of 60 different words, half of them in a male voice and half in a female voice. They rated each word for clarity and pronounceability on a scale of 1 to 5. Then they played a computerized board game for 20 minutes as a distraction. Finally they were tested on which words they remembered.
The test consisted of 120 words, so listeners had only heard half of them before. They were asked to press a button if they had heard the word before, and also to say whether they knew, remembered, or were just guessing. There was one more trick to the test: Half the words were spoken in the same voice they had been originally, but half were spoken in the other voice (formerly male voices were now female, and vice versa). Here are the results:
As you might expect, when the words were spoken back in a different voice, overall accuracy diminished significantly, but it was entirely due to the “remember” responses — listeners “knew” just as many words as they had previously. In a final twist, some listeners were given a shorter time to respond — just 700 milliseconds. How did these listeners do?
While respondents were overall less accurate, the same pattern emerged: significantly fewer “remember” responses and the same number of “know” responses when the words were spoken in a different voice.
So different conditions appear to make it more difficult to recall words we remember, but not words we know.
In a separate experiment, the researchers distracted listeners while they listened to the words. In addition to rating the pronounceability of the words, listeners also watched pairs of numbers on a computer screen, and they had to indicate whether both numbers were odd, both were even, or they were mixed. The test at the end was the same as before. Here are the results:
This time the listeners said they knew significantly fewer words when they were presented in a different voice, while the portion they remembered remained the same. As before, when respondents had to answer quickly, the same pattern held:
Overall accuracy diminished, but again the difference between words in the same voice and a different voice was entirely due to the “know” responses.
In two additional experiments, Gardiner’s team replicated the results using pictures instead of words. The researchers argue that these experiments show that the know/remember distinction isn’t simply a part of a continuum. This work, they say, suggests that knowing and remembering are qualitatively different phenomena. It’s also clear that being distracted at the time a memory is being formed biases the memory towards knowing rather than remembering.
It doesn’t necessarily make you more accurate, though. I looked up the “Garfield” answer and found that I must have been very distracted in high school: In my first draft of this post, I had him preceding Teddy Roosevelt.
Gardiner, J.M., Gregg, V.H., Karayianni, I. (2006). Recognition memory and awareness: Occurrence of perceptual effects in remembering or in knowing depends on conscious resources at encoding, but not at retrieval. Memory & Cognition, 34(2), 227-239.