ALTERNATING ALTERNATING TREATMENT DESIGNS and TREATMENT DESIGNS and

YOUYOU!!

Tristram Jones, Ph.D.Kaplan University PS512 Unit V

What the heck IS an Alternating Treatment

Design? (You ask!)

Alternating treatment designs rely on the rapid alteration of two or

more distinct treatments and record their effects on a single

target behavior!

GREAT SCOTT, DOCTOR --WHAT WOULD A THING LIKE THAT BE USED FOR???

Well… primarily…. The alternating-

treatment design is used in order to ascertain the comparative effect of two or more treatments alternated in rapid succession and correlated changes are plotted on a graph to facilitate comparison

Here is a REALLY SIMPLE example!

And you can alternate And you can alternate treatments within sessions, treatments within sessions, across different times of the across different times of the

day, or even on different day, or even on different days!days!

All aspects of treatment must be

counterbalanced!IVs must be presented inBlocks or randomly. If youhave 3 treatments, A, B, & C, then you spray themrandomly or group them inthe possible blocks, which Are ABC, BCA, CAB, ACB,BAC and CBA, right? Eachtreatment is repeated thesame number of times!

Counterbalancing helps to rule out a variety of extraneous variables!

This means that all differences in conditions, such as time of day, experimenter, or location of treatment, must all be repeated so as to be reliably counterbalanced to rule out confounds!

Remember! Some type of repetition is ALWAYS

necessary to show INTERNAL VALIDITY in

ABA design!

And even if your own textbooks won’t tell you, EXTERNAL

VALIDITY is a lost cause!

The second important point is that subjects should be able to

discriminate between treatments!Why on earth is this important? The text doesn’t bother tosay! Well, for one thing, it ensures that the IVs utilized aresufficiently distinct from one another. Remember when westudied multiple baseline design we learned that if DVsf DVsare too much alike, they may exhibit covariance that are too much alike, they may exhibit covariance that confounds research purposes– it is just too likely they willconfounds research purposes– it is just too likely they willcovary, so they don’t add much to verification! Well, thecovary, so they don’t add much to verification! Well, thesame can be said about Independent Variables. If they aresame can be said about Independent Variables. If they aretoo much alike, we might not be measuring a meaningfultoo much alike, we might not be measuring a meaningfulvariation of the DV! In fact, random chance could bevariation of the DV! In fact, random chance could bemeasured by accident! (COMPARE: measured by accident! (COMPARE: Assimilation effectsAssimilation effects – –discussed later.)discussed later.)

so make sure your so make sure your subject is aware, subject is aware, because a distinct because a distinct stimulus should be stimulus should be associated with associated with each each treatment!treatment!

SO THAT WAS THE BLEACHED WHALE BLUBBER, RICHIE, AND THIS HERE IS THE CURDLED FISH EYES!

Amazingly enough,you also do not needto use a baseline withAlternating Treatment Designs! (But you can!)

Who needs a baseline?• Whenever possible

baseline data ought to be collected, because two of the three basic types of ATDs actually do use such data—but the third does not! This has the advantage of allowing the treatment phase to begin immediately!

The three types of ALTERNATING BASELINE

• See. I thought you’d ASK, so here you go:

ATDs WITHOUT BASELINEBASELINE followed byATDBASELINE followed byATD with a FINAL TREATMENT phase

WAIT A MINUTE! There are really four kinds! We can also do a really

cool design called Alternating Treatment Design with CONTROL!

You just include NO TREATMENT as one of your

treatments HINT: Want some fun? Try it with AOD treatment!

“Thus: No treatment” can also be used as an IV to

act as a control! Yesterday when you had your seizure we gave you Depakote. Day before we gave you Dilantin! Today, we do nothing!

As is always the case with withheld treatment, there can be ethics issues, too!

You can have a real baseline in BASELINE FOLLOWED BY

ALTERNATING TREATMENTS design!• As in all single subject designs, baseline represents

a stable rate of responding.

• Works when treatment need not be rushed

And with baseline followed by alternating treatments and a final

treatment! Where science and ethics combine forces!

This works well ethically because

it is important to maintain the form

of treatment that works best. So: Collect initial baseline data. Introduce alternating treatments. Determine which works best. Continue using the most

effective treatment, Pretty simple, really!

BUT then there is the danger of dread carry

over effect!

A carryover effect is an effect that "carries over" from one experimental condition to another. Whenever subjects are placed in more than one condition, like in singles-subjects designs, there is a possibility of carryover effects…and they are internal validity threats!

1. Practice Effects – Occur when subjects get better at the task over time because of practice, so that they perform best in the later conditions.

Four types of Four types of common carry-over common carry-over confounds are as confounds are as follows:follows:

Fatigue EffectsFatigue Effects2. Fatigue Effects –

Occur when subjects get worse at the task over time because of fatigue. They might even quit trying and just “go through the motions.”

ASSIMILATION ASSIMILATION EFFECTSEFFECTS

3.Assimilation Effects – Occur when a stimulus is perceived as particularly similar to a preceding stimulus (assimilation)

Finally, a type of “Catching On…”

4. Hypothesis guessing” This is when repeated exposure to conditions makes it clear to subjects what the independent variable is, so that they “catch on” to the hypothesis being tested. In many cases, subjects will then behave the way they think you want them too, or the opposite if they are the stubborn type! .

PRESENTING THE DATA Teacher is interested in increasing her student’s rate of reading. She has two

fluency programs that she believes may work with Bob. She implements the two different programs on alternate days over 19 days. After the completion of the experiment, she is confident that intervention #1 will achieve better results for improving Bob’s reading skills

What about using

WITHDRAWAL?WITHDRAWAL?• withdrawal

procedures have been instituted following the sequential administration of treatments to target behavior(s) (Russo & Koegel),

• But not so much!

Counterbalancing is the key!• In many cases, the carryover effect in one

direction will simply cancel out the carryover effect in the other direction. This will always be truer if you test many subjects.

And here are the big three as they apply in ATD!

• PREDICTION! Each data point serves as a predictor of future behavior under the same treatment!

VERIFICATION! Each data point serves as verification of PREVIOUS performance under same treatment!

REPLICATION: Each data point replicates the differential effects of other treatments—in other words, the spread

should remain the same!

There is also a simultaneous and an adapted multiple treatment design—so you can have it all at once, or target different behaviors! They are tricky to analyze! So don’t worry about them unless you’re REALLY interested!