"Impulsive people have a way of understanding, and a mode of action, that, in comparison with normal deliberations and intentions, we would consider impaired. This impaired way of behavior shows itself as lack of control - acting on whim, giving in to temptation, doing what you have told yourself not to do.
"All varieties of impulse, whim, or urge are essentially the same: a distortion of normal desires and wants, a sort of seizure that overrides good sense. Impulsive people are not self confident but simply hope and wish for results. They have no long-term goals, only immediate urges. Their behavior is abrupt, immediate, and unplanned; the time between thought and execution is very brief.
This is not to suggest that quickness in trading is a negative. To the contrary, it is essential to good traders, but the difference is in the size of commitment the person takes on the spur of the moment, and the existence (or absence) of an underlying plan.
"The net outcome of unplanned behavior is that when failure occurs, the integrated process malfunctions and the person cannot accrue effective lessons from the loss. Without a plan, impulsive people can't develop sustained methods to determine what works and what doesn't. They can't understand why they failed, and they can't understand, as good traders do, that a failed plan is beneficial because it leads to avoiding the same mistakes in the future."
- Principles of Professional Speculation, Victor Sperandeo