IF THE VALUE of contribution to the larger non-academic community is any factor in tenure judgements, then it has to be either a lead-pipe cinch or "a lock" (or both) that the psychology department of Connecticut's Fairfield University has already awarded irrevocable lifetime tenure to Dr. W. Ronald Salafia. He surely deserves that and more.

You see, recently Dr. Salafia was both professionally competent and personally considerate enough to reveal what most of us already knew from personal embarrassment: a nine-digit ZIP code, like the one threatened by the Postal Service, is at least two digists too long for just about everybody's memory. Dr. Salafia put it beautifully: "The short-term memory is like a bucket that can hold seven gallons. If you load it with nine gallons, the bottom falls out, and you lose everything."

The telephone company obviously was on to something when it made its major move from six- to seven-digit phone numbers. Come to think of it, the song never could have been a hit if it had been "Pennsylvania 6-5000, and Nine-Five-three."

The short-term memory of which Dr. Salafia spoke so convincingly is the name given to that function of the brain that enables us to retain seven items for from 10 to 20 seconds.The seven-digit limit was first uncovered by the research of Dr. George Miller almost a quarter of a century ago. In Dr. Miller's work with thousands of persons, individuals frequently could memorize and repeat to him series of numbers up to seven. But almost never to eight or nine.

Dr. Salafia offers further comfort. Practically every one of us has an indentical short-term capacity. The inability to recall nine-digit ZIP codes has nothing at all to do, according to Dr. Salafia, with date of birth or IQ. That, in itself, is a relief, and sufficient reason for the good doctor's receiving tenure.

In addition to assuring us that just about everybody's capacity for remembering items like ZIP codes is equal, Dr. Salafia offers some reassurance and some ammunition against the Postal Service's proposed swelling of the ZIP.Terming the seven-digit discovery "an all-or-nothing phenomenon, Dr. Salafia says, "When something is lost, everything is lost." We know no one who could have said it any better.Take that, Postal Service.