Rats are highly intelligent and can be trained to perform simple tricks prompted by voice commands using repetition and rewarding with treats. Training requires consistency, ensuring always to use the same voice commands.
Rats can be trained to come when called, and this can be started by calling them and getting them to come to the front the cage and rewarding them with a treat. Training can then progress outside the cage waiting until the rat has wandered a little way away and then calling them to come fetch their reward using the same voice command. Ultimately a rat can be placed on the floor and trained to not only come back but to climb up its owners legs and body onto their shoulder to obtain their treat. However, it is best to wear thick trousers when performing this trick in order to avoid ending up with scratched legs!