I have spent 15 minutes looking for my sunglasses only to find them perched on my head.

In a conversation, I have been pressed for a response and then realized I haven't heard a word the other person was saying.

I have taken showers with my watch on.

I have gotten up at 7 a.m., showered and dressed for work before realizing it was Saturday.

If you recognize yourself in two or more of these statements, you're probably absentminded -- prone to lapses in attention. Chances are you spend a great deal of time looking for lost objects, making excuses for forgetting to do things, and apologizing for missing appointments. You may have a disturbing and painful tendency to walk into walls and trip over curbs, and you probably owe a fortune in library fines.

While the absentminded may be forced to endure barbs about premature senility, absentmindedness has little to do with memory. It's a wanderlust of the attention that may have a variety of causes, including boredom or depression, certain illnesses, nutritional deficiencies, and possibly, say some researchers, premenstrual tension. Most often, however, it's the product of lazy thinking habits.

Webster defines absentmindedness as a state of being unaware of one's surroundings or actions. Ellen Langer, professor of psychology at Harvard University, calls it mindlessness. "When you're mindless," she says, "you're responding as a robot -- automatically. You're not really there."

When you become too accustomed to your surroundings, too adept at performing tasks and too absorbed in an easy and convenient routine, your brain doesn't need to work very hard to propel you through your daily activities, and you float through your days mindlessly. It's a passive and unreceptive state in which your senses and thought processes are somewhat disengaged -- in neutral gear.

You see, but you don't observe. You hear, but you don't really listen. You act, but you are not truly conscious of your action. So when you can't find your keys, it isn't because you forgot where you put them -- you never registered putting them anywhere.

Granted, a certain amount of mindlessness is essential. If you had to think about each action you take, brushing your teeth or tying your shoes, for example, your brain would become so cluttered with mundane details that more creative or productive thought would not be possible.

But too much mindlessness can blunt the sensibilities. "If you are responding to the world mindlessly, you are not picking up what is going on around you," says Langer. You may miss insignificant information, but then again you could fall into a manhole. "You won't know whether it is important or unimportant information that you are missing until it's too late, so you need to figure out how to prevent mindlessness in the first place."

Letting go of absentmindedness requires a dedicated effort to change careless attention patterns. "First," says Langer, "you must make a commitment to yourself to recognize that you are not as aware as you think you are. This is a step that many people don't want to take. They usually think that mindlessness is something that somebody else has."

The next step is to force yourself to pay attention. One way to do this, say experts in time management, is to create visual associations to help you remember your actions. If you tend to misplace your keys, for example, make a mental note each time you set them down. If you place them on the kitchen table, imagine them driven into the wood, gouging a great hole. When you need to locate your keys, you'll remember that image. If you forget to take your watch off before showering, picture a giant clock at the bottom of the shower -- you'll probably never ruin another watch.

Devising memory triggers is another strategy. If you frequently leave the house without your briefcase, make a habit of leaving it in front of the door. When you trip over it often enough, you'll learn to never leave home without it.

But, while these techniques are helpful for minor bouts of forgetfulness, they don't really get at the root of absentmindedness: mental complacency. To truly overcome mindlessness, says Langer, you must make a conscious effort to do things differently, to upset your patterns so you have to start thinking again.

For example, suppose each time the telephone rings you habitually and unconsciously light a cigarette. Put the phone in a different place, suggests Langer, so the ring comes in an unusual way, grabbing your attention by making you walk to the phone in a different part of the room each day.

"It's like walking to work," says Langer. "You needn't take the same path each time." You can vary the path, and after a while, that variation can become as routine as the original path. But the point is to keep turning new corners, to take chances, to eliminate the predictable. "Look at new things," says Langer, "or look at old things in new ways." When faced with novelty, you are forced to respond mindfully, rather than automatically. Change and challenge jogs the brain from its waking nap.

"People should make it their goal to be more conscious of the world around them, to learn to be more discriminating," says Langer.