Behavioral Momentum
What is it?
• Stolen from physics: idea that an ongoing behavior will
continue unless it meets a disruptive force
• What is a disruptive force?
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Any change in the reinforcement/punishment schedule
A distracting stimulus
A change in body state: prefeeding, deprivation, drugs
Introduction of anything (that the animal notices)
Removal of anything (that the animal notices
• Measured as Resistance to Change
In a nutshell:
• Behavioral momentum refers to the tendency
for behavior to persist following a change in
environmental conditions.
• The greater the rate of reinforcement, the
greater the behavioral momentum.
Some setting conditions
• Two components (or choices)
• Organism must show stable responding on a response contingency
– Often a 2-choice response
– Can be 1 or more than 2
• Apply disrupter equally to the two components
• Leave baseline rates of reinforcement unchanged
– Usually, choice with richer schedule = higher Sr rate
– But: Resistance to change is independent of baseline rates
– Use concurrent chain schedules
Measurement considerations
• For single disruptor: (B0-Bx)/Bo
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Bo = baseline rate of responding
Bx = response rate at value of disruptor value
R1 and R2 are the rate of reinforcement
a = sensitivity to reward (matching law)
• If baseline = disruption responding: no change
• If baseline > disruption: get value >1
• If baseline <disruption: get value <1
Why use semilogrithmic axes?
• Use response rates RELATIVE to baseline
– Eliminates floor or ceiling effects for rates of
responding
– Produces a roughly linear line
• Slope of the function is invariant with respect
to multiplication or division: fast rats and slow
rats can get the same slope!
Some differences with schedules:
• Ratio schedules = higher rates of responding
• Use a free-operant procedure (not discrete trials)
(WHY!?)
• Rate of reinforcement determines resistance to change
relative to baseline
• Nevin:
– maintained response rate determined primarily by operant
response-reinforcer contingencies
– Resistance to change determined primarily by Classical
conditioning stimulus-reinforcer relations.
Physics metaphor
• Newtonian mechanics
– Moving body has both velocity and mass
– Under constant conditions: continues in motion at
constant velocity
– Velocity only changes when acted on by external force
• Velocity changes in proportion to the force and
inverse proportion to mass:
– Delta(v) = F/m
– (B0-Bx)/Bo = x/m where x = the “force” and m = the
“mass”
Keep going with this……
• Δv1=Δv2=x1/m1=x2/m2
– Ratio of the values of the assessment variable that
give equal changes to the 2 performances, relative
to their baseline is equal to the ratio of the
behavioral masses of those performances
• Say what? x1/x2 = m1/m2
And more:
• Can manipulate around a bunch
• Or B1/B2=c(r1/r2)a
– r1 and r2 are the rates of reinforcement obtained
by B1 and B2 respectively
– a = sensitivity of reinforcement
– C = bias
– Recognize this?
And two more
• m1/m2 = (r1/r2)b
– b = sensitivity of mass ratios to reinforcement rate ratios
• Thus: momentum ratios are given by product of the last 2
equations:
• (m1B1)/(m2B2)=c(r1/r2)a+b
– The ratio of the mass ratios * baseline rate of responding for
component 1 divided by the mass ratio * baseline rate of
responding for component is a function of:
• Inherent bias multiplied by
• The ratio of reinforcement rates for the two alternatives
• To the power of sensitivity to ratios of reinforcement AND sensitivity
of mass ratios to reinforcement rate ratios
And two more
• Relative momentum depends on:
– Relative rate of reinforcement AND
– Whatever operant or pavlovian factors that determine the values of
the exponents a,b, plus the multiplier c
• There you have it:
– behavioral momentum depends on both the relative rate of
reinforcement, the sensitivity of that organism to changes in relative
rates of reinforcement AND any classical conditioning that may serve
as a cue to changes in the stimulus conditions
• Responding changes as a function of resistance to change (and
resistance to extinction) AND the relative rate of reinforcement.
Okay, this is boring….Why?
1 example: PREE
• Behavioral momentum may provide better description
of resistance to extinction
– PREE: partial reinforcement extinction effect
– Responding is more persistent during extinction after
training on partial reinforcement than CRF
• Resistance to extinction = counter-instance of general
relation between resistance to change and rate of
reinforcement
– Extinction gives discrepant results because original
schedule no longer in effect
– This, then, makes significant difference in procedure
Extinction = counter-instance?
• Multiple schedule training with 2 PRF schedules
– Mult schedules flip flop: first 1, then the other
• Extinction proceeds less rapidly in presence of SD previously
correlated with higher rate of Sr
• Shows that resistance to change is positively related to
reinforcement rate on multiple schedules
• When control for procedures: CRF maintains performances
that are more resistant to change than those maintained by
intermittent schedules.
– True within subjects
– True in independent groups
Reanalysis of PRE
• Slopes of the EXT curves:
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Log r = log kC-kt
Where r = momentary response rate
C = total responses to extinction
t = time
k= rate constant of the exponential decay process
• Given by the slope of the function relating response rate to time
• Is independent of C
• The shallower the slope of the extinction effect, the greater the behavioral
mass (resistance to change)
• Analyzed lots of data: Conclusions were: rate of extinction is SLOWER
after CRF than after intermittent reinforcement
– Opposite of usual conclusion
– BUT: still not addressing initial decrement in EXT relative to baseline rates
Generalized decrement hypothesis?
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Behavioral momentum interpretation states
– The delivery of reinforcers and the consequences of nonreinforcement are themselves part of
the stimulus situation in which responding is reinforced
– With respect to these aspects of the stimulus situation, the difference between CRF and EXT is
greater than between PRF and EXT because nonreinforcement and its consequences have
been experienced during training
– Larger response decrements are routinely observed with larger changes of stimulus values in
studies of stimulus generalization
– Thus: One should find larger decrement in EXT after CRF than after PRF
– Follow this?
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Must control for stimulus cues when examining CRF vs. PRF
All experiences = part of stimulus conditions
During PRF: experience nonreinforcement routinely, thus SDs for nonreinforcement
During CRF: experience little nonreinforcement, no SDs for nonreinforcement
Thus: it is STIMULUS cues that cause the quick extinction in CRF-EXT vs. PRF-EXT conditions
Generalized decrement hypothesis?
– Follow this?
• Must control for stimulus cues when examining CRF vs. PRF
• All experiences = part of stimulus conditions
• During PRF: experience nonreinforcement routinely, thus SDs
for nonreinforcement
• During CRF: experience little nonreinforcement, no SDs for
nonreinforcement
• Thus: it is STIMULUS cues that cause the quick extinction in
CRF-EXT vs. PRF-EXT conditions
• That is: it is a stimulus discrimination issue, not a
reinforcement issue that produces PREE!
Confounding Effects in EXT
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Must apply a single, uniform operation to performance being compared for
resistance to change, or assessment is confounded
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EXT procedure = 2 factors:
– Termination of reinforcement
– Change in stimulus situation
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Momentum metaphor:
– Two bodies with different masses moving at different velocities subjected to 2 forces to 2
components
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Heavier, slower body = CRF
Lighter, faster body = PRF
– One component of opposing force: friction (termination of Sr)
– Other: application of brake
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Note: applies DIFFERENTLY to the 2 bodies
Heavier to CRF as is heavier and slower,
Diminishing force as the bodies slow down
– When breaking terminates: only friction left
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Heavier body decelerates more slowly than lighter body, regardless of velocities when brake is
removed
Effect of differential braking component MUST BE REMOVED to compare relative masses of 2 bodies
Confirming experiment:
• Examined EXT after CRF and PRF using within-subjects design with
extended training
– Attempted to equalize decremental effects of transition to
nonreinforcement by providing repeated EXT after explicit signal
– Each session began with reinforcement, always ended on EXT
• On even days: CRF- EXT
• On odd days: PRF-EXT
• Used 2 different signals in same box
• Results:
– Initially: more responses during EXT after PRF than CRF during early
sessions
– This diminished over trials
– CRF produced shallower EXT (slower) than PRF
WHY is this important? Applications
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Must determine if have free operant or discrete trials
– Discrete trials are different!!!!
– Behavioral momentum relies on free operant conditions
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What rate of reinforcement should be used to reinforce once behavior =
established?
– If rate is desired: consider it a free operant
– If quality is desired: may or may not be free operant
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Important to distinguish whether the therapist wants:
– large increases in responding
– Perseveration of responses, regardless of magnitude (just keep the behavior going)
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Extinction is rare: no behavior goes completely unreinforced or punished
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Response decrements due to generalization decrements are more likely than those
due to EXT
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But: remember free operant PREE effects: CRF = more resistance to EXT
Mace and Basketball
• Assumption: to generate a high level of
momentum for a specified class of behavior,
arrange a high rate of reinforcement for a high
rate of responding in the training situation!
• Once behavior is established, should persist
effectively in situation correlated with rich
schedule of reinforcement, even during EXT
periods.
Basketball data
• Teams: 1989 NCAA
• Trained observers scored videotapes of 7
basketball games
– Three classes of behavior:
• Reinforcers: 3,2,1 pts and turnovers favoring target team
• Adversities: turnovers favoring other team, missed field goal
and foul shots, commissions of fouls
• Response to adversities: outcome of target team’s first
possession of ball following adversity (included all of above)
Results:
• First hypothesis: team’s response to adversity
would vary as a positive function of its local
reinforcement rate immediately preceding the
adversity
• Local rate of reinforcement prior to adversity calculated
by # reinforcing events during 3 min prior to adversity/3
minutes
• Local rates categorized into
– 0-0.3: low rate of reinforcement
– 0.67-1.0 moderate rate of reinforcement
– >1.3: high rate of reinforcement
Hypothesis 2
• Calling a TO from play will be an effective
intervention for reducing the opponent’s rate
of reinforcement and disrupting behavioral
momentum.
– Local reinforcement rate of opposing team plotted
as function of local reinforcement rate of target
team
– Examined 3-min period before, and after TO and
aggregated across all TO periods.
Conclusion
• Can apply behavioral momentum to real world
studies
• 2 ways to alter behavior:
– Make behavior more resistant: Train with high
rates of reinforcement: more resistant to
disruptors!
– Use behavior to disrupt ongoing flow: Disruption
as a means to reduce responding and interrupt
momentum!
Problem in ABA: How to eliminate an
inappropriate behavior quickly
• Obviously can punish.
– Ethics problems
– We will discuss this on Wed.
• Can use EXT:
– Can be slow
– Can result in transient increase, aggression
• Can use DRA: Differential reinforcement of an alternative behavior
– Find an opposite behavior to reinforce
– If want to decrease out of seat, reinforce sitting in seat.
• What do the data suggest as the best alternative?
DRA and Resistance to Change
• One problem in ABA: long term generalization and
maintenance of gains
• Need to create durable and generalizable
interventions.
• Nevin: behavior momentum: 2 independent features of
discriminated operant:
– Ongoing response rate: function of R-Sr relation
– Resistance of this response to change when disrupted:
function of total rate of reinforcement in context
DRA and Resistance to Change
• DRA and behavioral momentum:
– Look at extinction vs. short/long periods of satiation
vs. DRA
– DRA tends to produce lower target response rates but
has stronger resistance to change
– Thus: DRA does not elicit as high of responding but it
is a more persistent result
• Again….do you want high rates of responding or more
resistance?
– Do a direct clinical test
Method
• Three kids with DD
– Andy (age 7): autism and severe MR
• Follow gestures and 1 step directions
– Tom (age 7): DS and ADJD
• Food stealing, elopement and tantrums
– Jackie (age 4): girl: severe MR, microcephaly, moderate hearing loss
• Aggression and SIB
• Response to 1 step instructions delivered by manual signs
• Target behaviors:
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Andy: hair pulling
Tom: food stealing
Jackie: hair pulling, scratching, hitting, head butting = aggression
DRA behaviors: appropriate toy play (A and J) and appropriate
requests for food (T)
Method, con’t
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Pre-study functional analysis: Target behaviors and their consequences
– Andy: hair pulling maintained by adult attention
– Jackie: aggression maintained by access to food
– Tom: stealing food maintained by access to food
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Conditions:
– Baseline: VI reward for inappropriate target responses
– EXT: response blocking
– DRA: alternative behavior reinforced
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Andy: Toy play
Tom: appropriate food requests
Jackie: toy play reinforced with social attention (food a diet issue)
Then: several phases:
– Andy: BL-DRA-EXT-BL-EXT
– T and J: BL-EXT-BL-DRA-EXT
– Ran to visual stability
Results
• Examined target response rates across phases
– Found DRA intervention decreased behavior greatly
– EXT condition: response burst then decrease
• Primary interest: relative resistance to Ext following
baseline versus DRA rates of reinforcement
– EXT condition: reductions in target behavior took 3x as long as
DRA
DRA condition: Showed persistence-strengthening effect of DRA
on target behavior
• DRA reduced occurrences of target behavior
• Associated with greater resistance to change during adjacent EXT
phase compared to EXT following BL
What does this mean?
• While the DRA was effective in reducing the
inappropriate target behavior, it actually made
it MORE resistant to EXT!
• Thus, you may be inadvertently shooting
yourself in the foot: using DRA while allowing
reinforcement of inappropriate behavior can
make inappropriate behavior more difficult to
eliminate!
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Experiment 2
4 rats (not kids) in operant boxes
Procedure:
– First did preliminary training: lever pressing on both levers
– Baseline: 3 cycles of 3-component multiple concurrent
schedules
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Each component = 6 min
Presented quasirandomly without replacement within a
session
Separated by 30-s intercomponent period without any
experimentally programmed events
– EXT test: single test session
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All food Sr discontinued
Used same schedule, but no reinforcement
Components 1 and 2: signaled by same visual stimuli as in
baseline.
Stimulus compound used in 3rd: combined stimuli used in
Components 1 and 3
Why:
– Signaled reinforcement history in Component 2 and
Component 3 (stimulus compound) were equal during EXT
(120/hr)
– But were greater than signaled reinforcement history
correlated with Component 1 (24/hr)
Results
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Calculated log proportion of baseline responding on right lever across successive blocks of EXT
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Least resistance to change: Component 1:
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MOST resistance to change:
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Longest responding on EXT in Component 2:
visual stimuli correlated with overall programmed rates of reinforcement
same reinforcement rate for target and DRA responses
Component 3 responding lower than Comp. 2
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Responding took the shortest amount of time to EXT during component 1
visual stimuli correlated with LEAST amount of Sr and no DRA
Reinforcement rate was same as 2 but stimuli different
Even though used DRA, the stimulus conditions were different enough that reduced resistance to change
Suggests that DRA must be used with different stimuli than that which used when reinforcing target
response
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Stimulus cues affect resistance to extinction
Be careful what you are cueing
Exp. 3
• A human example of using DRA with different stimulus cues
• 2 males with DD
– Mickey: 11 years old, moderate MR, some speech, severe disruptive behavior
– Paul, 21, severe MR: nonverbal, severe disruptive behavior
• Target behaviors:
– Mickey:
• throwing items, pounding on table, shouting, slapping teacher
• DRA: “break please” request
– Paul:
• throwing or destroying materials, pounding on table, kicking table, slapping instructors
• DRA: touching “stop” card
• Functional analysis: Behaviors maintained by escape
Exp. 3
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Baseline multiple concurrent schedules
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Component 1: reinforcement of target behavior
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Reinforcement for target response
instructor provided prompts to request a break from instruction on a fixed interval 20-s (FI 20-s)
schedule.
Contingent on requests for breaks, the instructor provided a
break
Component 3: DRA reinforcement only
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without DRA
when target response occurred, kid got to take a break.
Component 2: negative reinforcement for target R and DRA (asked for break and escaped tasks)
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Presented randomly without replacement
5-10 min between components
1 to 2 sets of 3 component sessions per day 5 days per week
Therapists wore different colored gowns as SD for components
reinforcement for DRA but no reinforcement of disruptive behavior;
breaks from instruction were not contingent on disruptive behavior, but only on request for break.
EXT test: no reinforcement of target or DRA behaviors
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Varied discriminative stimuli
EXT test 1, 2 and then compound BL C1 + C3 stimuli
Results:
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Baseline:
– Component 1: most target behavior
– Component 2: target behavior much lower; DRA reinforced 3.75x more than disruptive
behavior
– Component 3: lowest rates of target behavior; actually eliminated target behavior in Mickey
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Resistance to EXT:
– Shown as % of baseline responding
– Resistance to EXT greatest in Component 2
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Discriminative stimuli identical to baseline
Both subjects showed EXT burst
– Component 1: lower resistance to EXT
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Discriminative stimuli identical to baseline
Baseline rates of reinforcement about 25% of component 2
– Component 3: combined stimuli
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Rates of disruptive behavior during EXT much lower than in component 2, comparable to component
1
Shows that persistence-strengthening effects of DRA can be reduced or avoided by
using DRA in context separate from that correlated with history of reinforcement
of unwanted target behavior.
What does all this mean?
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Behavioral momentum looks at changes in rate and direction of ongoing behavior
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Compare disruptor condition to baseline rates of responding
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Persistence can be increased if provided CRF or rich reinforcement during training
– Disruption can be effective for reducing target behavior (e.g., disrupting other team or
disrupting inappropriate behavior)
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But: 2 things controlling behavior:
– Reinforcement rate
– Stimuli that are paired with reinforcement
– IF want DRA to become more effective: must use in context other than original context in
which target response was reinforced
– Otherwise, are teaching persistence
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The persistence-strengthening effects of DRA can be reduced or avoided by using
DRA in a context separate from that correlated with a history of reinforcement of
unwanted target behavior.