Over time I’ve come to appreciate that feature of the iMac that asks its users, “Are you sure you want to permanently erase the items in the Trash?”

To underline the importance of this question, the iMac adds this reminder: “You can’t undo this action.”

I’ve been using Macs long enough to know the consequences of the action. That’s why the computer’s nagging inquiry occasionally annoys me, usually when I’m in the grips of a frenzy brought on by a mess of files that seem to have created themselves . . . for no reason that I can recall. So into the trash they go!

Then comes the question . . . and the reminder (which treats Trash as a proper noun).

IN FAIRNESS, I admit this reminder sometimes prevents mistakes. Unfortunately, more times than not, my trash reflex is quicker than my brain and — ooops! — items are erased before I’ve reconsidered.

But the subject here is not the trash reflex; it’s that other thing — the brain: Wouldn’t it be nice if it alerted us when certain things in our memory bank were about to be forgotten . . . and did we wish to prevent this?

But no, the brain arbitrarily erases items all the time . . . like where did we hide all of those passwords we’ve been forced to create since we entered the computer age? Or what's the date of our wedding anniversary? And why am I standing in front of the refrigerator?

MOST AT RISK are words seldom used, especially the names of tools and common household items that only come to mind when something goes wrong. Depending on my level of stress, I sometimes even forget what to call the remote (aka clicker) that often seems to disappear while my wife and I are watching television.

God’s solution, obviously, was the creation of the word “thing,” which the brain never forgets. So in this case, I'd look at my wife accusingly and ask, "Where did you put it?" To which she'd reply, "Put what?" And I'd snarl, "The thing that changes the channel!"

I figure my brain takes it for granted we'd always put something as important as the remote in plain sight, so there was no reason to keep the word handy. The brain has a limited capacity, so it dumps a load of little-used words, names, dates and telephone numbers into a junk drawer and is often slow in retrieving them.

My brain also likes to tease me by hiding things — the word "algorithm," for instance, and the sequence of digits in my Social Security number.

I’M FREQUENTLY reminded of that scene in the entertaining Cary Grant-Audrey Hepburn movie “Charade,” when Grant’s character tries to make the acquaintance of Hepburn’s Regina Lampert. But she turns him away with the film’s most-quoted line: “I already know an awful lot of people and until one of them dies I couldn’t possibly meet anyone else.”

(To which he replies, “Well, if anyone goes on the critical list, let me know.”)

And so it also must be that our brains won't process new data until it discards some of the old. I believe the reason I’ve always had trouble recalling names is my brain thinks I'll never see those people again.

THEN WHY does my brain retain so much useless information? That's the mystery. Like why do I remember a singer named Jo Anne Greer recorded a song called "Forty Cups of Coffee" back in the 1950s ... or that a teenage actress named Denise Nickerson was freaky good in a 1971 TV movie called "The Neon Ceiling" ... or that in 1951 an outfielder named Frank Saucier was considered a sure bet for major league stardom?

In the meantime, my brain continues to mess with me without permission. If you'll excuse me, my brain says I've got to go to the kitchen. But when I get there I won't remember why.