Most writing courses focus on the mechanics of writing. Grammar, sentence structure, eliminating redundant words, active versus passive voice. The mechanics are important, but that’s not how you become more productive, efficient and effective.
A cognitive approach is about the psychology of writing, yours and the readers. It’s about how you translate raw thoughts into words, how readers put their own meanings into your words, and how you structure your text to guide the reader to your intended meaning.
It’s also about understanding your personal writing process. What techniques do you use for generating content? For organizing and outlining? How do you go about revision? How do you get feedback on your writing and when?
Part of the psychology, yours and the readers, is 'affect' or 'emotion'. How do you feel about writing? What are the positive and negative associations words carry?
Understanding the psychology is what makes you a more effective writer.