No additional comment fields

It is good if you cannot see those fields ??
Anti-spam plugin is like invisible captcha.
The question was answered instead of user and this process is invisible for user.
The main idea of the Anti-spam plugin is that spam should be blocked invisibly for admin anf for users.

Disable javascript and css in your browser and you will see those hidden fields.

Did you understood now how it works?
If you have more questions than you may ask them here and I will try to help.