In Chapter 7, I found it very interesting how humans retain information differently, depending on how it is perceived. People are typically more capable of retaining echoic memories (sound) for longer (about 5 to 10 seconds), compared to iconic memory (visual) in which people only hold onto for a second.
Also, once these things are in our short-term memory, which again is brief, they begin to decay, and be interfered with by new incoming memories. In order to retain information longer, "chunking" and "rehearsal" methods can be used. I found this part the most informative, because I find myself using an "elaborative rehearsal" technique it for schoolwork concepts. This technique utilizes relating or manipulating the new information to other information stored. Once you understand how your brain and how it remembers information, you can better retain information for future tests!
There are exceptions to normal human memory, one case is of a man who is autistic but displays a skill of eidetic imagery, or photographic memory.