this effect is often called the "clever hans effect". it is used in psychology to describe when an animal or a person senses what someone wants them to do, even though they are not deliberately being given signals. it is important to take this effect into account when testing animals' intelligence or human intelligence. an animal may need to be separated from its trainer if their true intelligence is to be observed. on the other hand, an animal may be upset when it cannot see its trainer, so it might not give the right answer. this problem can often be solved by creating a situation in which the trainer does not know the right answer.