When you have had a few too many drinks, chances are your vision starts to get fuzzier. This is an effect of the alcohol, but the condition also has a name. Inattentional blindness is the failure to notice a fully visual but unexpected object. The object is normally missed because the person was focused on something else or otherwise occupied. This phenomenon is different from other forms of blindness such as change blindness, repetition blindness, visual masking and attentional blink. It is also called perceptual blindness.

This odd disability happens when a person is focusing on too many things at once, or when focus is impaired. Many experiments have been done on this issue, and have shown that it proves true. The study that revolutionized the concept of perceptual blindness is called the invisible gorilla test. This trial was conducted by professors from the University of Illinois and the University of Harvard. In the research project, the subjects were told to watch a short video where two groups of people in black and white shirts pass a basketball. The subjects are told to count the number of passes made by one of the teams, or to keep count of how many times the ball is bounced versus being passed in the air.

While the people pass the ball around, a person walks through the scene in a full gorilla suit. In other versions of the video it is a woman carrying an umbrella. After watching the video, test subjects are asked if they noticed anything odd in the film. About 50 percent of all subjects say that they did not notice anything, and completely missed the gorilla. This is because they were too engaged in counting the amount of passes the teams were making. The results of this famous test show that the relationship between what is in one's visual field and what one perceives is mostly based on attention, not sight. Versions of this test can be found online, where people can experience perceptual blindness themselves.

When a person is sober, inattentional blindness can occur because the person is not expecting something to happen, or because he or she is occupied mentally. Often someone who is thinking about too many things at once will go on autopilot, and can't pick out anything that is happening around them. Instead, they are directing their attention to a thought, conversation, or another area, and miss things that are right in front of their noses. This is one of the reasons that people can "lose" items that are in plain sight.

When a person's mind is jumbled because of the effects of alcohol, then inattentional blindness is often active. This means that the driver is acting without any awareness of what is around him or her, and that can be very dangerous. When perceptually blind, individuals may fail to see the lane markers, barriers in the road, cars driving along, or objects which have fallen onto the pavement. In some cases, a drunk driver will even crash into a building, because he or she was not focused enough to notice the structure. When something unexpected happens on the drive home, a perceptually blind person may not think to react. As you can see, it is scientifically proven that it is dangerous too get behind the wheel when you are affected by alcohol. While a drink or two may be all right, drinking yourself into a mentally disoriented state can become fatal for you or other drivers out on the road. Refrain from driving drunk, in order to save yourself and others from the danger of a serious collision.