Retroactive interference (retro=backward) , when we learn something new it tends to interfere with what we have learnt initially, this means the new learnt task interferes with the task we have learnt earlier such that we forget the earlier task.
This is more common if our memories have similarities such as learning a new langauge may tend to interfere with the old language that you have learnt.l before.
Having learnt Italy now interferes with the ability to learn Spanish.
