Answer:
Proactive interference
Explanation:
Whenever Mark tries to recall his new cell-phone number, he keeps getting it mixed up with his old cell-phone number. Mark's failure to remember his new cell-phone number is probably caused by Proactive interference.
Proactive interference is a state in which the interference is in the reverse direction. This means that a person suffering through proactive interference will experience a constant interference from older memories whenever he tries to remember newer memories. This is most common in terms of phone numbers, just like in the case above.
