Memory can be tricky at times, especially when you are learning something that is similar to something you have learned in the past. For example, when I moved to the United States three years ago I had to make a lot of changes in my life, one of them being getting a new phone number.  Having had the same number for over two years made it difficult for me to adapt to my new phone. When I started making friends in high school, I sometimes gave them my old phone number because my brain was confusing it with my new one. There are a lot of people that I didn’t get the chance to know very well because they had no way of contacting me, since they had the wrong phone number. It wasn’t until the end of my first semester in my new high school that I memorized my new number completely, and finally stopped mixing it up with my old one. This type of confusion is called proactive interference, which is one of the two main types of interference where the memories we try to create get confused with memories we have from the past. In other words, proactive interference is experiencing difficulty in learning or memorizing something new due to information we already know. Confusing my new phone number with my old one is one example of proactive interference because the information I learned before (my old number), kept interfering with my ability to memorize the new information (my new number). Since both memories were similar, my brain confused the new one with the old one for almost one semester until I finally adapted. Another example of proactive interference would be when teachers mix up their student’s names because they get them confused with the names of students they have had in the past. Interference is a very common aspect of the human memory, especially when it comes to memorizing two very similar things. The old memory has been in your brain for a longer period of time than the new one, which makes it harder for you to adapt since your brain will keep remembering the similar information you already know. It is a matter of time and memory exercises for your brain to fully grasp the new memory and stop confusing it with the old one.