In lab studies in which two participants play a game against each other, if one participant is told that the other person is going to be competitive and non-cooperative, this usually results in the first participant .

acting in an aggressive, hostile behavior.                                                          

Explanation:

Aggressive behavior is determined as an individual's impulsive and reactionary behavior that produces a consequence of breaking or destroying household rules & regulations or laws. Aggressive behavior is often considered as unpredictable and violent.

Hostile behavior is considered as a type of "emotionally charged" aggressive behavior. It is considered as another word for aggression and anger.

In the question above, the given statement signifies "acting in aggressive & hostile behavior".

true