Question

to determine whether hanss performance was simply a ruse, the german board of education sent a team of scientists to observe von osten and his horse. the team concluded that there were no tricks involved in the horses shows. however, oskar pfungst, a psychologist associated with the team, eventually realized that hans did not possess any mathematical acumen. instead, he was just picking up on subtle changes in peoples body language and using these cues to arrive at the correct number of taps. pfungst showed that people tend to make faint movements, such as tilting their heads slightly upward, when they expect to hear a certain answer. this propensity to provide unconscious behavioral clues has become known as the clever hans effect. scientists are now very careful to take this effect into consideration when designing experiments. what is the meaning of propensity as used in the passage?
need

tendency

preference

intention

Explanation:

In the passage, it says "people tend to make faint movements...". The word "propensity" is used to describe this inclination. "Tendency" means an inclination or likelihood to act in a certain way, matching the context. "Need" is about requirement, "preference" about choice, and "intention" about purpose—none fit as well as "tendency".

Answer:

tendency