Differential outcome effect in the horse.
Giving each correct response its own unique reinforcer sharpens discrimination in horses and people.
01Research in Context
What this study did
Researchers worked with a horse on a simple discrimination task.
The horse had to pick one of two symbols.
Each correct choice earned a different food pellet.
Sometimes the foods stayed the same for each symbol.
Other times the foods switched or stayed the same for both.
What they found
When each correct symbol had its own unique food, the horse scored 80-90 percent correct.
When the foods were random or identical, accuracy dropped.
The unique-food setup created clearer stimulus control.
How this fits with other research
Sparaci et al. (2014) later saw the same boost in kids and adults with Down syndrome.
They used face photos instead of horse symbols, yet the unique-reinforcer trick still lifted memory scores.
De Meyer et al. (2021) pushed it further.
Children with ADHD reached typical-learning levels once each correct response earned its own reward.
Together these papers show the differential-outcomes procedure works across species and skills.
Why it matters
You can borrow this simple tweak tomorrow.
Pick two clear reinforcers your client loves.
Link each one to its own correct response or picture.
Expect faster learning and fewer mix-ups.
It costs nothing but a little planning.
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02At a glance
03Original abstract
Three horses were trained with a discrimination task in which the color (blue or yellow) of a center panel signaled the correct (left or right) response (lever press). Reinforcing outcomes for the two correct color-position combinations (blue-left and yellow-right) were varied across phases. Discrimination performance was better when the combinations were differentially reinforced by two types of food (chopped carrot pieces and a solid food pellet) than when the combinations were randomly reinforced by these outcomes or when there was a common reinforcer for each of the correct combinations. However, the discrimination performance established by the differential outcome procedure was still 80% to 90% correct, and an analysis of two-trial sequences revealed that the stimulus color of the preceding trial interfered with discrimination performance on a given trial. Our demonstration of the differential outcome effect in the horse and its further analysis might contribute to more efficient control of equine behavior in the laboratory as well as in horse sports.
Journal of the experimental analysis of behavior, 2000 · doi:10.1901/jeab.2000.74-245