Final answer:
Lukas's quick shift in attention from a familiar toy to a new one shows he has habituated to the familiar toy, which is a basic form of learning and an indicator of cognitive development.
Step-by-step explanation:
The scenario provided wherein Lukas, after being shown two toys, quickly shifts his attention from a familiar one to a new one, demonstrates his habituation to the familiar toy. Habituation refers to the decrease in response to a stimulus after being repeatedly presented over time. Lukas looking longer at the new toy is indicative of him having habituated to the old one, as he shows decreased interest in it and an increased interest in the new, novel one. In cognitive development, this ability leads to learning about and exploring the environment more efficiently.