If you're watching an action thriller (I have unfortunate tastes in movies
), you'll sometimes see a guy with a gun drawn, hiding behind a pillar in a garage. He'll poke his head out and then pull back too fast for the bad guys (or possibly the good guys) to put holes in him. But that split second is enough for him to see where those bad guys (or good guys) are.
How does this work? George Sperling, in his 1959 Harvard Ph.D. dissertation, gave us an explanation—though he ran his experiments in a laboratory with a tachistoscope (an old-fashioned projector with a timing device), rather than in an underground garage with guns. His experiments worked along these lines. You're looking at a blank screen, and you see very briefly (for 50 milliseconds) an array of letters and numbers. For example, it might look like this:
7 I V F
X L 5 3
B 4 W 7
You then write down all the characters you remember having seen. Here's something interesting: As you're writing, you have the feeling that you can remember all the characters, but you're forgetting some of them before you can put them down on paper. To test this possibility, Sperling did something clever. You watch the screen, see the characters, and then you hear a tone that tells you which row to write down. It turns out that you're perfectly capable of doing this accurately, whichever row is indicated, even if you don't remember what you saw in the other rows.
This is pretty cool: we do see and remember a great deal of what's presented to us, it's just that the information doesn't stay around for very long. You probably know that our memory can be broken down into different categories, depending on its characteristics; for example, long-term memory is for information that we generally describe as "what we know". Some of the categories are less familiar outside psychology, but they're just as interesting, such as visual short-term memory.
And I'm describing this because...? I'm writing a book, and I spend a good deal of time crafting sentences and paragraphs in my head. Once I start to write them down, though, the sentences often fall apart. I can't quite remember how I've expressed my ideas. This isn't the same phenomenon that Sperling studied, but it's similar enough in spirit that I was reminded of his work.
G. Sperling (1960). The information available in brief visual presentation, Psychological Monographs: General and Applied
, 74, 11: 1-29. [pdf]