Looking at perseverate and perseveration, you may guess that the latter was formed by adding a suffix to the former, but that is not the case. Perseveration is actually the older term. It has been around since the 1500s, when it was used as a synonym of perseverance (which at one time was pronounced, like perseverate and perseveration, with the stress on sev, instead of on ver). In the early 1900s, psychologists adopted perseveration for the act of repeating a behaviour over and over again—for instance, continually repeating the same syllable or word might be called “verbal perseveration.” Shortly afterwards, those scientists wanted a verb for such acts of repetition, so they changed the -tion of perseveration to -ate and perseverate was born.

Examples

To ensure the accuracy of data, the scientist necessarily perseverates, repeating each experiment many times and comparing the results.

“I have been perseverating on the same questions, chewing on the same information, running through the same scenarios endlessly.” — Brynn Lackie, The Toronto Sun, 7 Sept. 2020