What is the incorrectly used adverb in the paragraph?

Although a few words may be spelled in more than one way, the dictionary only lists one acceptable spelling for the vast majority of words. Spelling errors rarely cause complete misinterpretation of a message, but they do hamper a reader’s ability to decipher a message rapidly. Spelling errors also indicate that the writer lacks sufficient regard for the reader to make an effort to spell correctly. In addition, most readers will quickly notice spelling errors and, therefore, lower their opinions of the writer’s competence. Because poor spelling hampers reading, shows lack of consideration for the reader, and indicates incompetence, writers should never send messages containing misspelled words.