Answer:
Retroactive interference
Explanation:
Retroactive Interference ( Retro- backwards) is the tendency of forgetting a previously learnt memory due to the presence of a new memory. Interference simply means the hindrance of an old memory in the unconscious human mind because of the new memory.
Michelle learning French affects her already learnt Spanish language. It forms an interference in the way of speaking to her grandmother. The acquired memory clashes with an encoded memory. Thus, she inserts french into Spanish while conversing with her grandmother.