This discussion was buried in another thread, I thought it deserved a thread of it's own.
Is it expectations, (the dog has found the other birds long and therefore expects the bird to be long)?
Or is it because the dog has forgotten the shorter bird?
More importantly, What is the best way to improve a dog's success at a trial? Secondary selection or Ideal selection?
With secondary selection, the handler is having the dog pick up shortest of the remaining birds second. A close corollary is that in training you don't have a dog run past a short station that it has not yet retrieved. Creating an expectation for the dog to pick up the shortest bird before the longer bird even if the longer bird is more attractive.
In contrast, with Ideal selection as I understand it, one is training the dog to be comfortable running by a short bird and picking up the attractive long bird and then coming back and picking up the short bird: