I bought a book by Eric Franklin that focuses on using imagery to achieve "dynamic alignment." Here are some thoughts from it.
If posture and thought process are intimately connected, then, in a sense, your thoughts are constantly sculpting your posture, changing your alignment. The reverse holds true as well: Your posture influences your thinking. Your thoughts are part of a powerful matrix that influences your posture. THe flood of words and images around you affects the way you sit, stand, and walk. Notice how comforting, encouraging words of praise from a parent of trusted teacher can immediately improve your posture: "Good! Well Done! Perfect! Beautiful! Excellent job!" Conversely, observe the tension stifling all movement in a class being told it's "not good enough."
He also says that since our posture is constantly being sculpted, trying to hold yourself in "good posture" goes against nature, because it becomes something static. We must accept this changing nature of our bodies and realize that good posture is a perpetual quest. This is reminiscent of an idea of Isadora's. When creating her school, one of her stated goals was to help her students make their bodies into an "instrument as perfect as possible."
