People sometimes use the slang term "brain lock" to describe a moment in which they are unable to think or process information. This phenomenon is also referred to as a "brain freeze," with both idioms referencing the idea that the brain is temporarily frozen or locked in place, and therefore unable to perform any functions. There are any number of reasons why someone can experience this sensation, and some researchers have conducted studies to understand why this happens, and how people can cope with it.
Someone may experience a moment of brain lock in the middle of a conversation as he or she forgets the thread of the conversation or can't think of a word. This type of brain lock is relatively benign, although it can be embarrassing when someone commands the floor and then stands frozen for a moment, unable to think or speak. People can experience this in the midst of an impromptu conversation or a prepared speech, suggesting that it may be caused by nerves, stress, or distractions, rather than the type of situation in which it occurs.
More seriously, people sometimes find that they are unable to remember how to do something. For example, a driver might momentarily forget how to apply the brake, or a diver might not remember the correct sequence of decompression stops. In these cases, the brain lock is usually readily apparent to the person experiencing it, and the person suffering from it may appear blank or confused for a moment until he or she remembers what to do.
When people find themselves in a moment of brain lock, it sometimes helps to focus on the next step of whatever they are doing. Some psychologists have theorized that when people think ahead or get distracted, they are more prone to brain lock, because the brain gets confused for a moment. The momentary hiccup may be resolved by refocusing and reminding the brain of the task at hand.
This figure of speech is not usually used in the medical community, because it is so imprecise. Repeated experiences of confusion and an inability to perform basic tasks can indicate an underlying neurological condition, but the occasional bout of brain freeze is usually not a cause for concern. Someone who finds that he or she experiences brain lock in the same setting over and over may want to see a psychologist to see if there is an underlying emotional cause, or a neurologist, to explore possible neurological reasons.