If someone ever invents an overshadowing Bingo game, Lewis and I will win! 
About Overshadowing
Sometimes a stimulus we try to classically condition has more than one aspect that can be sensed, like an object that can be both seen and smelled. This kind of stimulus is called a compound stimulus. The phenomenon of overshadowing may occur when compound stimuli are conditioned because one of the simple stimuli will likely prevent the other/s from being conditioned fully or at all.
I recently encountered a situation where potentially five different stimuli were “competing” to be classically conditioned. And of those five, the one most likely to “win” the conditioning was not the one that I needed the most. I had to tackle the problem, because it was in a training project that was important for Lewis’ wellbeing.
Oromucosal Medicine Administration
Lewis has been diagnosed with sound phobia to fireworks and thunderstorms, and one of his medications is to be delivered topically to his gum and cheek tissue.
The instructions for administering this medicine require that the human wear protective gloves so as not to touch the medicinal gel, which can be absorbed through, for example, a cut in the skin. Gloves are a new thing for Lewis.
I thought about whether I should use classical conditioning to help him have a positive response to the gloves and gathered up what I needed. I use disposable kitchen gloves for a lot of tasks, so that’s what I got out. Whoa! These gloves make a distinctive noisy rattle when touched or manipulated. You can’t even get them out of the box without the dog hearing them.
You probably see where this is going.
I wanted Lewis to have good feelings about the gloves. But what aspect of them? How many things are potentially different for a dog when you put a glove on your hand for a husbandry task, one that includes putting your finger in the dog’s mouth? How about:
- the sight of the glove on the hand
- the sound the glove makes
- the feeling of being touched by a gloved hand
- the odor of the glove
- the taste of the glove
We’ve potentially got all five senses involved; the gloves present a compound stimulus.
Bingo?
How about another list? How many things about the gloves might bother Lewis? No need to repeat; it’s the same list. But knowing him, I would guess that having a gloved finger stuck in his mouth between his cheek and gums would bug him the most. But of all these, the sound often happens first, and is super salient. How can I classically condition the mouth touch without it being overshadowed by the crackle of the glove?
The Environment Would Like a Word
The plastic kitchen gloves I have are awful for the environment. I would make a different decision now. There is no perfect disposable glove yet, but latex is made from rubber and some latex gloves can be biodegradable. Reusable rubber gloves would be better than what I have, but they are too bulky for this job with this dog. Feel free to comment with suggestions.
Solutions to the Overshadowing Problem
So, how do I make sure that Lewis has positive feelings about being touched (in the mouth) by the gloves, given that classical conditioning is more likely to attach to the sound of them? Here are the possibilities I considered.
Different gloves: I’m sure some of you are internally screaming a solution. Get different gloves! Quieter ones! Good idea. I’ll be looking for a better choice. But in the meantime, I’ll proceed with what I have.
Workarounds: There are some things I could try to do about the sound. I could put on the gloves in a far part of the house and play masking sounds while I did that, just to be sure. Then I could approach Lewis and do whatever step of the plan comes next. Show him a gloved hand, treat. Or touch him with a gloved finger, treat. That could prevent some of the predictive power of rattling the gloves. But when I show him or touch him, the gloves will still make noise.
Use an operant training plan: This is the solution I chose. The gloves were not scary to Lewis; they were just new and weird. So rather than aiming for classical conditioning, I went for desensitization coupled with operant conditioning.
For our first session, I tossed him a couple of treats when I got the gloves out. Then I reinforced sniffing the glove, nose-targeting the glove while I held it loosely, and nose-targeting it while it was on my hand. Then I asked him to do a chin rest on a towel in my lap with the glove on top. Lewis said, “This is easy money!”
In the next sessions, I had the glove on my right hand and touched his cheek while I held his muzzle with my left. We had previously worked on this step without the glove.
The video includes excerpts from the three training sessions where we progressed from him accepting my finger in his mouth to accepting my gloved finger in his mouth. We spent six to seven minutes of training over three sessions, which was more time than he needed.
Watch with sound if you want to hear how noisy the gloves are (and hear me say, “Good boy!” about a thousand times).
Going Forward
The operant work with the gloves made them predictors of good things (classical conditioning rode along). This work gave Lewis a great foundation for the next step: putting a syringe between his cheek and gum while wearing gloves. The gloved finger was a good early substitute for the syringe.
Compound Stimuli
Multiple simultaneous stimuli are happening all the time. When presenting an object, you can bet that most dogs will smell it as well as see it. Lots of visual stimuli make noises, too. As one textbook points out, it’s almost impossible to avoid multiple stimuli (Pierce & Cheney, 2008, p. 58). This experience has made me think about them a lot more. The Bingo game is not all that unusual. I’m pleased I figured out a way to win this time.
Thank you to the several professionals who provided materials and direct help for Lewis’ husbandry training. I could not have done it alone!
Copyright 2025 Eileen Anderson
References
- Pierce, W. D., & Cheney, C. D. (2008). Behavior analysis and learning (4th ed.). Psychology Press.
