Why are glasses on your head so hard to find?

Taking off glasses is usually a small action. They fog up, press on your nose, or you want to rest your eyes, so you push them onto your head. At that moment, your hand knows where they are. But once you start talking or open a bag, another activity pushes that action aside. Your blurry view makes it feel as though the glasses are gone, and your hands are already holding something else. In 1979, psychologist James Reason asked 35 volunteers to keep a two-week diary of such 'actions not as planned.' The more practiced an action was, the more it ran without conscious monitoring, and often left no memory of having been done at all. Reason saw this as the price of actions running on autopilot.

When something is missing, your eyes usually check where you last left it: the table, the sofa arm, or the entryway shelf. The top of your head rarely makes the search list. Until you touch it, it is outside your field of view, and after a while your skin gets used to the weight. It is like not noticing your watch or clothes touching your skin all day. That is how you end up walking around the house with your glasses still on your head.

When this happens often, you may worry that your memory is slipping. But in a 2007 study that reused Reason's method, 189 healthy volunteers recorded an average of about 6.4 such slips in a single week. It happens to everyone. The Alzheimer's Association also describes misplacing things from time to time and retracing your steps to find them as a typical age-related change. The signs worth watching for are putting things in unusual places and finding it hard to retrace your steps at all.

Checking the top of your head and your pockets before searching often ends the hunt. If it keeps happening, choosing one place to leave your glasses means less wandering. Whether it is the corner of a desk or a dish by the door, putting them in the same place each time makes your hand go there first next time. It also helps to say 'glasses, on my head' out loud as you push them up. A moment of attention attaches to an action that was running on its own, making it much easier to recall later.