In laboratory animals, partial or intermittent reinforcement schedules resemble which of the following?
O The animal first learns to lever press 10 times for food reward; then he is switched to a schedule where he receives half the amount of food reward for 10 lever presses.
O The animal first learns to lever press 10 times for food reward; then he is switched to a schedule where he is required to lever press 20 times for the same food reward.
O The animal first learns to lever press 10 times for food reward; then he is switched to a schedule where he is only reinforced with food reward on half of the trials.
O none of these.