Final answer:
You experienced proactive interference, which is when old memories interfere with the recall of new information, as you called to wish your mother a happy birthday on the wrong date.
Step-by-step explanation:
In the scenario described, where you mistakenly wished your mother a happy birthday on the 24th instead of the actual date, the 27th, you experienced proactive interference. Proactive interference occurs when old information interferes with the recall of new information. In this case, your previous memory of your mother's birthday being on the 24th hindered your ability to remember the updated information—that it is actually on the 27th.