Paying little or no attention to things, pertaining to only one side. This usually occurs on the side opposite the location of the injury. In extreme cases, the person may not bathe, dress or acknowledge one side of the body.

Unilateral neglect is a disorder of attention where patients fail to attend to stimuli, such as objects and people, located on one side of space. It most commonly results from brain injury to the right cerebral hemisphere, causing visual neglect of the left-hand side of space. Although most strikingly affecting visual perception (known as 'visual neglect'), neglect in other forms of perception can also be found, either alone, or in combination with visual neglect.