First, preemptive and preventive uses of force are often justified by claiming either that there is substantial risk of a future attack or that it is difficult to ascertain how dangerous the target is.
Short-Term Memory: Up to 7 Items, But Highly Volatile. Many psychology experiments have shown that our short-term memory can hold only a limited number of separate items. The average is about 7 items, plus or minus 2, depending on the individual. You can easily confirm this by reading someone a series of words that have no connection with one another, then asking this person to repeat them.
Because each row contains only 4 items and subjects must store only 1 row, performance is not limited by the fact that only 5 items can be stored in short-term memory. I. f subjects can report 90% of the letters in the cued row, they presumably had a memory of 90% of the entire array at the time of the cue. If the cue is too late, they store randomly-selected items rather than storing only the items in the cued row.