Earlier theories of the mind - like the formal discipline theory - assumed that things like reason, language and attention were like muscles and that any activity strengthened them. It led to views that learning Latin and geometry was essential even thou...

People that develop expertise in multiple areas are able to solve a wide range of problems.

Thorndike's replacement theory was not correct. He was wrong in thinking that only the superficial elements of a task needed to match.

Learning ideas are useful to a point. To make a general idea useful, some key obstacles need to be overcome: