Variable reinforcement schedules generally demonstrate greater resistance to extinction than fixed reinforcement schedules

The answer to the given statement is true.

This is because variable reinforcement schedules are less predictable than fixed reinforcement schedules. There are two possible types of variable reinforcement schedules: variable-ratio or variable-interval.

Variable-ratio reinforcement schedule means that the reinforcement would only be given when the individual exhibits the desired behavior according to a number of responses – these numbers are unpredictable for the subject. Variable-interval uses the same approach, however, the unpredictability lies on the period of time from when the desired behavior appears to when the reinforcement would be given.

This unpredictability causes extinction to be harder for the reinforced behavior since the subject might think that the reward for their behavior might still be given.

accelerated heartbeat, raise in blood pressure, slow in digestion, raise in blood sugar and perspiration. (myers' psychology for ap 2nd edition pg 87)