Chess and Thomas (1977) identify three basic types or clusters of temperament (an individual's characteristic way of responding). What are these three?

1. The difficult child; 2. The easy child and 3. The slow to-warm-up child.

Explanation:

On their work called "Temperament and development" from 1977, Thomas, A., and Chess, S. describe what they found, that babies could be categorized into one of these three groups.

The difficult child has slow to accept new experiences; second we have the easy child which is adaptable and last the slow to-warm-up child, who has low adaptability and low mood intensity.