Diminished ability to concentrate (Human Phenotype Ontology id HP_0031987) is the inability to focus or concentrate on a specific task, activity, or object. The subject may find themselves unable to grasp or understand written text and re-reads frequently without understanding. Familiar tasks or activities are severely compromised due to the lack of ability to concentrate. Thinking through multi-step problems is typically very difficult or impossible, leading to avoidance of such activities. Also known as: Concentration problems, Labored thinking, Lack of concentration, Poor concentration.