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?– 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 – 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:

– 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?

• 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?• 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• Must apply a single, uniform operation to performance being compared for resistance to

change, or assessment is confounded

• EXT procedure = 2 factors:– Termination of reinforcement– Change in stimulus situation

• Momentum metaphor:– Two bodies with different masses moving at different velocities subjected to 2 forces to 2

components• Heavier, slower body = CRF• Lighter, faster body = PRF

– One component of opposing force: friction (termination of Sr)

– Other: application of brake• 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• 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

• Must determine if have free operant or discrete trials– Discrete trials are different!!!!– Behavioral momentum relies on free operant conditions

• 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

• Important to distinguish whether the therapist wants:– large increases in responding– Perseveration of responses, regardless of magnitude (just keep the behavior going)

• Extinction is rare: no behavior goes completely unreinforced or punished

• Response decrements due to generalization decrements are more likely than those due to EXT

• 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:– 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• 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

• Conditions:– Baseline: VI reward for inappropriate target responses– EXT: response blocking– DRA: alternative behavior reinforced

• 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!

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• 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• 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• Calculated log proportion of baseline responding on right lever across successive blocks of EXT

• Least resistance to change: Component 1:– Responding took the shortest amount of time to EXT during component 1 – visual stimuli correlated with LEAST amount of Sr and no DRA

• MOST resistance to change:– 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– 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– 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• Baseline multiple concurrent schedules

– 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

• Component 1: reinforcement of target behavior – 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)– 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– 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– Varied discriminative stimuli – EXT test 1, 2 and then compound BL C1 + C3 stimuli

Results:• 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

• Resistance to EXT:– Shown as % of baseline responding– Resistance to EXT greatest in Component 2

• Discriminative stimuli identical to baseline• Both subjects showed EXT burst

– Component 1: lower resistance to EXT• Discriminative stimuli identical to baseline• Baseline rates of reinforcement about 25% of component 2

– Component 3: combined stimuli• 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?• Behavioral momentum looks at changes in rate and direction of ongoing behavior

• Compare disruptor condition to baseline rates of responding

• 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)

• 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

• 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.