Original:  Although Dweck's work in this area built on the foundation laid by Nicholls, the fundamental difference between the two scholars' works was the attribution of an individual's goal orientation: Nicholls believed that the goal orientation held by an individual was a result of the possession of either an internal or external referent, while Dweck considered the adoption of a particular goal orientation to be related to the theory of intelligence held by that individual.
Revised:  Although Dweck's work in this area built on the foundation laid by Nicholls, the fundamental difference between the two scholars' works is the attribution of an individual's goal orientation: Nicholls believed that the goal orientation held by an individual was a result of the possession of either an internal or external referent, while Dweck considered the adoption of a particular goal orientation to be related to the theory of intelligence held by that individual.
Edit intent: fluency