Gestalt psychology focuses on the idea that the whole is greater than the sum of its parts. It was developed in 1910 by Max Wertheimer, Wolfgang Kohler, and Kurt Koffka. Some key principles of Gestalt psychology include the laws of proximity, similarity, closure, good continuation, pragnanz (good form), and figure/ground. These laws describe how humans naturally perceive and group visual elements as a whole. Gestalt psychologists also studied insight learning through Wolfgang Kohler's experiments with apes solving problems using tools.