Final answer:
A pattern of repetitive, uncontrollable thoughts is called an obsession. Obsessions are part of Obsessive-Compulsive Disorder (OCD), which also includes compulsions as a response mechanism. Phobias are excessive fear reactions, and hallucinations are perceptions without external stimuli.
Step-by-step explanation:
A pattern of repetitive, uncontrollable thoughts is called an obsession. These thoughts can be persistent and intrusive, often causing significant anxiety or distress to the individual. Obsessions are a core component of Obsessive-Compulsive Disorder (OCD), a mental health condition characterized by the presence of obsessions, compulsions, or both.
Compulsions, on the other hand, are repetitive behaviors or mental acts that a person feels driven to perform in response to an obsession or according to rules that must be applied rigidly. These behaviors are aimed at reducing distress or preventing some dreaded event or situation; however, they are not connected realistically with what they are designed to neutralize or prevent, or they are excessive.
Phobias and hallucinations are different types of issues. A phobia is an excessive and irrational fear reaction towards a particular object, place, or situation, while a hallucination is a perception in the absence of an external stimulus that has qualities of real perception, essentially sensing something that isn't there.