This is one of the popular experiments mentioned in motivational books. Here is summary from a motivational webpage:
At the beginning of the experiment a number of fleas are placed in a jar. The natural reaction of the fleas is to jump out. After that a glass lid is placed on the top of the jar. Now the fleas fly high, hit the lid and fall back down into the jar. After a short time fleas adjust and begin jumping lower – until they start jumping slightly below the glass lid, in order not to hit it anymore. After three days the glass lid is removed. Since the fleas had already learnt to limit themselves from jumping high, they staid in the jar and there was no longer a lid needed to keep them inside. They have already been conditioned to the fact that they cannot escape from the jar and they have accepted that fact. Now no matter whether the lid is on or off the fleas will stay in the jar forever. Even more: when/if the fleas reproduce their offsprings will duplicate the behaviour and will not jump high either.
Now I've seen it cited many times, but without any proper background. There is one video on youtube presenting the experiment, but there is no source about how exactly it was conducted or proof about the behaviour of offspring.
To sum up, I have two questions:
- Do fleas really jump lower after being 'trained' in a lid? Does this behaviour persist?
- If so, is this behaviour passed onto next generations?