Bias is in spirit like tilting the brush or drawing with the edge of it at set amount. In Brush #9 you should still be able to see what it does and it's the same it would do for Brush #2,3,4 and 5. Think of it like phases of the moon.
It will respond to the direction in which the brush goes or points.
Very cool, I'd love to see what you're doing with it, especially with those art classes!
![kudos :ob](./images/smilies/icon_thumbsup.gif)