reinforcement schedules

Meaning: A reinforcement schedule decides which responses get reinforced. Continuous reinforcement rewards every response and gives the fastest learning. Partial (intermittent) reinforcement rewards some responses and learning is slower, but the behavior resists extinction more. The four partial schedules are:

Fixed-ratio: reward after a set number of responses (every 10th). Fast responding, with a short pause after each reward. Variable-ratio: reward after an unpredictable number of responses (slot machines). High, steady responding. Fixed-interval: reward for the first response after a set time. Responding speeds up as the reward time nears, giving a scalloped graph. Variable-interval: reward for the first response after an unpredictable time (checking for a text). Slow, steady responding.

On the MCAT: A passage describes a rat, pigeon or person and asks you to name the schedule, or shows a cumulative response graph. A steeper line means a faster response rate. Scallops point to fixed-interval, and a steep, smooth line points to variable-ratio. Questions also ask which schedule is most resistant to extinction. Partial beats continuous, and variable usually beats fixed.

Common confusion: Ratio schedules count responses, while interval schedules depend on time, so extra responding within an interval does not bring the reward sooner. Also, continuous reinforcement is not the best for a lasting behavior. It teaches fastest, but the behavior extinguishes fastest once reinforcement stops.