In most cultures, we tend to scold when someone has underperformed and congratulate when someone over-performs. This might wrongly give the perception that people improve their performance after being scolded when in reality they would have improved performance anyway since they were performing below their average and naturally they would have come back to their mean performance.
Scolding does very little or nothing to affect people's performance despite what we may observe. We are biased to see causality when in reality there's a natural regression to the mean.
The same way, after congratulating people, it might seem like they don't perform as well afterward, but it's the same effect taking place, "regression to the mean". Giving recognition and congratulating in public might have a long lasting effect to keep people motivated, there's no causality between congratulating and going back to lower performance. Hence, be kind to people ;)
This was inspired by a section of the Book "Thank fast, think slow" by Daniel Kahneman.