The individual differences principle emphasizes the influence of prior knowledge to results of learning. Design effects are stronger for learners with little prior knowledge, which results in different optimal instructional design for intermediate learners or beginners.

Prior knowledge implies at least partly developed schemata due to which students with prior knowledge have more free cognitive resources than beginners when learning from same material.

In practice, individual differences mean that more experienced learners will not full exploit their potentials when learning from materials designed for learners with no prior knowledge.