The fourth dimension of habit as described by Pinkham:
Triad of a Habit
The deleterious effects produced by a habit depends upon the three factors – Duration, Frequency & Intensity.
 a. Duration: The amount of time spent indulging in the habit. 
 b. Frequency: The number of times the habit is activated in a day.
 c. Intensity: The vigor with which the habit is performed.
Key Concept:
Pinkham has added a fourth dimension to oral habits, ie., Direction.
Direction
Frequency
Intensity
Duration