The basic cycle that defines many people's OCD is divided into obsessions and compulsions — hence, obsessive-compulsive disorder. MIND, a mental health charity, explains obsessions and compulsions, respectively, as intrusive, upsetting thoughts, and the behaviors that people with OCD perform to attempt to cope with or drown those thoughts out. Intrusive thoughts can take many forms; one essay published in Broadly focused on a woman's obsessive thoughts about whether she might kill her partner, a fear that came not from her own will or desires but from unbidden anxiety. The Royal College of Psychiatrists notes that the definition of intrusive thoughts is broad; they can include ideas, phrases, vivid distressing images, doubts, perfectionism, and rumination over a single topic or action for long periods of time. The key characteristic for people with OCD is that these thoughts are deeply distressing or anxiety-provoking, and cannot be calmed or banished by conventional methods.
In many circumstances, OCD UK explains, compulsive behaviors develop because the intrusive thoughts involve imagining hurt or harm to oneself or loved ones. If you don't wash your hands repeatedly, for instance, the thought insists that you might catch germs and so harm yourself or the people around you. However, the compulsive behavior doesn't serve to negate or make the fear go away; for people with OCD, it reinforces the belief and maintains anxiety levels. "For someone with OCD," OCD UK notes, "an anxiety-provoking event creates negative interpretations about what might or could happen. Even when nothing bad happens, the anxiety remains high until the person carries out their safety seeking behavior — the compulsion. Therefore because these negative interpretations still remain, the same anxiety-provoking thoughts continue to necessitate further safety-seeking behaviors, so instead of digging themselves out of a hole, they are digging that hole deeper."
Many OCD behaviors revolve around obsessions that are concerned with harm or danger, whether from hygiene or environmental risks. Psychologist Dr. Eliza M. Belle told Bustle in 2016 that people with OCD "repeatedly check things that they associate with harm or danger," from electrical outlets to locks. The dangerous objects or situations may not carry evident connotations to outsiders. OCD sufferers can develop advanced and complicated superstitions about how their actions might affect those around them; if they keep everything in the right order or perform a particular task, they'll be keeping themselves and others from harm.
If you think this sounds like keeping rabbit's feet for good luck or avoiding opening umbrellas indoors, you wouldn't be off-base. Neurologist Peter Brugger wrote in 2010 that superstitions and obsessive-compulsive behaviors seem to exist on a continuum, but that ordinary superstition takes place in an entirely different part of the brain than obsessive-compulsive beliefs about order and protective ritual. This connection between the two shows that a nuanced understanding of OCD symptoms is not all that far off, even for people without OCD.