The difference between reflective and spontaneous behavior can be seen by comparing the way people think with the way they write. Typically the difference is not only in vocabulary, but also in the way in which they express themselves.

Writing takes time, which the brain can use to reflect on what is being written. When people speak, they have far less time to reflect on what they are saying. Generally, writing is reflective while speaking is spontaneous.

Those who are extroverts are notorious for opening their mouth and putting their foot in it. This is spontaneous behavior: neither thinking things through nor considering the consequences before we speak.

However, introverts are usually more reflective. They demonstrate more reflective action. This means they think before they speak. Alas, too often they also self-censure to the point that what needs to be said doesn’t get verbalized.