Quiz
Question: In what way are fixed-ratio (FR) and variable-ratio
(VR) reinforcement schedules:
(a) similar?
(b) different?
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Quiz
Answer:
similar:
different:
based on number of responses
fixed: number fixed
variable: number varies
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Have I witnessed a hurricane?
Answer: Heck yeah!
X
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
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Reinforcement
Definition
A
stimulus change
 contingent on some aspect of a response that
 increases the future probability of the response
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Distinguishing Characteristics of Reinforcement
Type
Social
 Edible
 Tangible
Reinforcement history
 Primary (unconditioned) reinforcer: Reinforcer whose effects
are not dependent upon prior learning
 Secondary (conditioned) reinforcer: Reinforcer whose effects
are acquired through pairing with other reinforcers

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Determinants of Reinforcement Effects
1. Reinforcer Parameters




Immediacy
Contingency
Magnitude
Quality
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Determinants of Reinforcement Effects
2. The Establishing Operation (EO)

Antecedent event that:
Alters the effectiveness of a given reinforcer, and
Increases the likelihood of behavior that has produced that form
of reinforcement in the past

Types of EOs
Deprivation: Typical EO for behavior maintained by Sr+
Aversive stimulation: Typical EO for behavior maintained by Sr-
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Schedules of Reinforcement
Schedules of reinforcement determine the frequency and distribution
of behavior in time
Definition:
A formula (or rule) describing the probability that a given R will
produce reinforcement; or, a formula describing the proportion of
Rs that will be reinforced
Schedules are based on a continuum of probability values
Contingency
Every R Sr
No Rs  Sr
Some Rs  Sr
Schedule
Probability of Sr
Continuous Sr (CRF)
Extinction (EXT)
Intermittent Sr (INT)
p =1.0
p=0
0 < p < 1.0
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Advantages of Intermittent Reinforcement
Prevents satiation: INT Sr maintains state of deprivation (EO)
 Resistance to EXT?: INT Sr is less predictable than CRF;
therefore; change to EXT more difficult to discriminate
 Can produce high rates of R (more Rs required for Sr)
 Naturalistic: Most schedules in natural environment are INT
 Cost effective: Easier for agent to administer

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Basic Schedule Parameters
Response requirement:
 Ratio: Sr based on number of Rs
 Interval: Sr based on time elapsed since last reinforced R
Regularity:
 Fixed: Requirement constant between Sr deliveries
 Variable: Requirement changes from one Sr delivery to another
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Basic Schedules of Reinforcement
Fixed
(Requirement
for Sr constant)
Variable
(Requirement
for Sr changes)
Ratio
Interval
(# of Rs)
(Time since last reinforced R)
Fixed Ratio (FR)
Fixed Interval (FI)
(Sr delivered following
fixed # of Rs)
(Sr delivered for 1st R after
fixed amt of time since
last reinforced R)
Variable Ratio (VR)
Variable Interval (VI)
(Sr delivered following # (Sr delivered for 1st R after
of Rs that varies around variable amt of time
since last reinforced R)
an average value)
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Schedule Effects on Behavior
Ratio
Interval
(High R rate)
(Moderate R rate)
Fixed
Fixed Ratio (FR)
(Irregular
R rate)
Fixed Interval (FI)
High, irregular rate
(PRP, break & run)
Moderate irregular rate
(FI scallop)
Variable
Variable Ratio (VR)
Variable Interval (VI)
High stable rate
Moderate stable rate
(Stable R rate)
Real life examples?
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Response Patterns Generated by Basic Schedules
CUMULATIVE # OF RESPONSES
40
FIXED RATIO
30
VARIABLE RATIO
FIXED INTERVAL
VARIABLE INTERVAL
20
Sr+
10
Break & Run
PRP
0
0
10
20
30
SESSON TIME
40
50
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Response Patterns Generated by Basic Schedules
CUMULATIVE # OF RESPONSES
40
FIXED RATIO
30
VARIABLE RATIO
FIXED INTERVAL
VARIABLE INTERVAL
20
10
0
0
10
20
30
SESSON TIME
40
50
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Response Patterns Generated by Basic Schedules
CUMULATIVE # OF RESPONSES
40
FIXED RATIO
30
VARIABLE RATIO
FIXED INTERVAL
FI Scallop
VARIABLE INTERVAL
20
10
Sr+
0
0
10
20
30
SESSON TIME
40
50
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Response Patterns Generated by Basic Schedules
CUMULATIVE # OF RESPONSES
40
FIXED RATIO
30
VARIABLE RATIO
FIXED INTERVAL
VARIABLE INTERVAL
20
10
0
0
10
20
30
SESSON TIME
40
50
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Guess the Schedule!
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How hard is graduate school?
Answer: pretty darn hard
Answer: but it also depends
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Quiz #2
Question:
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Activity: 9/12
Preference Assessment Methods: to identify potential
reinforcers
Indirect: checklists (RAISD, RAQ)
Descriptive: Premack
Experimental: Paired-stimulus Preference Assessment (Fisher
et al. 1992)
Reinforcer Assessment: to validate reinforcement effects
Practice various schedules
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