Chapter 8 – Intermittent Reinforcement & Schedules

Definition: Schedule of Reinforcement

• A schedule of reinforcement = the rule specifying which occurrences of a target behaviour will be followed by a reinforcer.

  • Answers both how and when a response produces a consequence.

  • Dichotomy:

  • Continuous Reinforcement (CRF) – every response reinforced.

  • Intermittent Reinforcement (INT) – only some responses reinforced.

Jan’s Math‐Problem Programme (Applied Illustration)

• Initial problem: Jan off-task, many errors.

• Intervention (ratio‐thinning procedure):

  • FR $2$ → praise every 2 completed problems.

  • After stability, raised to FR $4$, then FR $8$, then FR $16$.

• Outcomes:

  • Work rate ↑ sharply; non-attending dropped to $0\%$.

  • Demonstrates power of INT for maintenance after acquisition.

Continuous vs. Intermittent Reinforcement

• CRF (a.k.a. FR 1)

  • Examples: faucet gives water, light switch gives light, puddle splashes.

  • Functionally the opposite of extinction; behaviour never contacts non-reinforcement.

• INT

  • Reinforcement only occasionally = "sometimes".

  • Extremely resistant to extinction; drives persistent behaviours (e.g.
    slot-machine gambling).

  • Ethically neutral: can sustain prosocial habits or addictive/problem actions.

Acquisition → Maintenance Heuristic (Always / Sometimes / Not-Never)

• During acquisition (learning phase) – use ALWAYS (CRF).

• During maintenance – thin to SOMETIMES (INT).

• Avoid NOT-NEVER; stopping reinforcement entirely risks extinction.

Advantages of Intermittent Schedules

• Less satiation; capitalises on deprivation.

• Greater resistance to extinction.

• Produces more consistent response patterns.

• Transfers more readily to natural reinforcers (praise, money, smiles).

RATIO Schedules ("How Many")

1. Fixed Ratio (FR n)

• Reinforcer after a fixed number $n$ of responses.

• Produces: high steady responding, post-reinforcement pause (PRP).

• "Higher the FR value ⇒ longer the PRP."

• Example: Piecework pay $\text{FR}\,10$ ($1$ USD per 10 items).

2. Variable Ratio (VR n¯)

• Reinforcer after a variable number around a mean $\bar{n}$.

• Little/no PRP; very high rate; most resistant to extinction.

• Examples: slot machines, unpredictable praise for math problems.

Post-Reinforcement Pause (PRP)

• Brief pause after reinforcement before next response run.

• Length governed by schedule value (FR size).

  • E.g. Nurse: work 8 h → 16 h off; work 16 h → 32 h off (longer value, longer pause).

Ratio Strain

• Sudden, large increase in ratio requirement ⇒ response breakdown.

• Example: Daily Pokémon card (FR 1) abruptly changed to every 14 days (FR 14) ⇒ child quits.

• Remedy: gradual thinning to avoid “value strain.”

INTERVAL Schedules ("How Long")

3. Fixed Interval (FI t)

• First response after a fixed time $t$ reinforced.

• "Scallop" pattern: low early, accelerating near interval end; PRP length = interval length.

• Example: TV show every Thursday 7 p.m. ⇒ $\text{FI 1 week}$.

4. Variable Interval (VI t¯)

• First response after variable interval (mean $t¯$) reinforced; steady, moderate rate; no PRP.

• Example: Checking email/Facebook – update after 3 min, 15 min, 6 min ⇒ $\text{VI 8 min}$.

LIMITED HOLD (LH)

• Deadline added: reinforcer available only for a brief window after interval elapses.

• Notation: FI 10 min / LH 30 s, FR 20 / LH 3 min, etc.

• Powerful motivator → induces urgency.

• Illustrations:

  • FR 20 burpees within 3 min to earn water (FR 20/LH 3 min).

  • Subway every 10 min, doors stay open 30 s (FI 10 min/LH 30 s).

  • Police ticket quota: 50 tickets in 30 days (FR 50/LH 30 days).

DURATION Schedules

• Require the behaviour to continue for a period, not just occur once.

5. Fixed Duration (FD t)

• Behaviour must persist continuously for exactly $t$ to access reinforcement.

• Produces PRP.

• Example: Paid for working continuously for 1 h (FD 1 h).

6. Variable Duration (VD t¯)

• Continuous behaviour for variable period around mean $t¯$.

• No PRP.

• Example: Rubbing sticks: 10 min today, 20 min tomorrow; $\text{VD 15 min}$.

Interval + LH Combinations (Schedules 7 & 8)

• FI/LH and VI/LH already illustrated; treated as distinct intermittent types.

Concurrent Schedules & The Matching Law

• Concurrent schedules: two or more schedules available simultaneously for different behaviours.

  • Example: Holding urine (VD – unknown wait for restroom) vs. drinking beer (FR 1 sip per lift) while in line.

• Matching Law: Allocation of responses/time matches relative reinforcement rates.

  • Behaviour with richer/denser reinforcement wins when they compete.

  • Influenced by schedule type, immediacy, magnitude, and response effort.

Ethical, Philosophical & Practical Reflections

• INT can sustain altruistic acts (holding doors), learning persistence, but also gambling addiction or maladaptive tantrums if mis-applied.

• Designers must weigh social impact; with great resistance to extinction comes responsibility.

Common Pitfalls

• Unintentionally creating INT for problem behaviours (e.g., sporadically giving into tantrums) ⇒ hard-to-extinguish patterns.

• Over-thinning → ratio strain → apparent extinction.

Implementation Guidelines

1. Match schedule to behaviour (ratio for discrete responses, interval/duration for sustained activity).

2. Choose convenient parameters for observers & setting.

3. Use objective tools (timers, counters) to detect correct reinforcement moments.

4. Thin gradually to avoid strain; follow always → sometimes continuum.

5. Explain “rules of the game” to learner to maximise predictability & cooperation.

Quick Reference: Eight Intermittent Schedules Covered

• FR, VR, FI, VI, FD, VD, FI + LH, VI + LH.

Exam Focus Reminders

• Define each schedule (ratio/interval/duration, fixed/variable, LH).

• Be able to write notation: e.g., $\text{VR 2}$, $\text{FI 15 min/LH 1 min}$.

• Explain post-reinforcement pause rule (higher value ⇒ longer pause).

• Explain ratio strain and limited hold conceptually & with examples.

• Discuss advantages of INT and its powerful resistance to extinction.