When John realized that zebras do not make the same noises as horses, and that they run differently than horses, he became confused. John was experiencing .

disequilibration or disequilibrium

Explanation:

Disequilibration or disequilibrium, occurs when an individual is in a state of confusion as to what he/she understands and what is seen or encountered. It occurs when an individual is unable to process or link new information with current knowledge base or mental schemas. It is different from equilibration which occurs when an individual is able to assimilate new information to fit into existing information or mental schemas.

John was experiencing disequilibration when he became confused about the features of the zebras and the horses.