Taking your jumper to a horseshow usually means getting the horse exposed to many different colourful and potential fear eliciting stimuli (otherwise known as ‘spooky jumps’!).
Some horses are more fearful of such ‘scary’ objects and jumps than others and I often meet riders that have problems with their horses refusing to jump the colourful ‘scary’ jumps.
This issue is usually addressed in training by introducing many colourful and oddly looking jumps to habituate the horse to jumping different types of jumps. Many riders recognize the situation where their horse refuses the ‘scary’ jump the first time, but once they’ve jumped it once they are no longer scared of it and the following approaches are nice and easy.