Perseveration is considered a subset of the “hyperfocus" which is widely associated with ADHD. It is the act of continuing with a behaviour (repetition of a word, phrase, gesture, action, or thought) after the stimulus for the behaviour has stopped. So, it is a response that was appropriate to the first stimulus but is inappropriate to the changed second stimulus.
A person who perseverates finds it difficult to stop a particular action and switch to another.
I watched a child during a swimming lesson where he was repeating the phrase “I can’t, I can’t” even once he had achieved the goal of using the kick board independently and had a smile of accomplishment on his face.
He was unable to transition to the new situation because his perseveration was holding his attention and his working memory hostage. He became inflexible because he couldn’t manage the flow of new information by linking the new information being acquired by his senses to the information already in his working memory.
Other examples of the continuous involuntary repetition associated with perseveration are repeating a story long after the topic has changed and the story is no longer relevant, or repeatedly stirring food on the stove, or scribbling over existing lines on a piece of paper.
Some people with ADHD can accomplish great things due to their ability to hyperfocus (concentrate intensely on a specific task to the point where it could possibly dominate one’s thoughts and interfere with other actions). Hyperfocus can be immeasurably helpful for deep immersion into a project but can also cause problems when someone ignores their surroundings too much. Hyperfocus can lead to burnout and result in less productivity than if the approach to the task had been better managed.
Both perseveration and hyperfocus result in a disrupted control of attention which creates challenges with directing attention, sustaining attention, and switching attention. Both conditions lead to unbalanced behaviours that disrupt the natural flow of people’s lives by perhaps causing them to misplace their keys and lock themselves out of their homes or miss important appointments.
Assistance with bringing perseveration to a conscious level, and with learning strategies to redirect attention, can be very helpful for someone struggling with the symptoms of ADHD.