Dory, the lovable regal blue tang fish, has a tendency to forget things almost instantly after becoming distracted. In turn, this makes Marlin the clown fish’s journey to find his son more problematic, being that the Dory is the sole witness to his son’s abduction. At first, Marlin tolerates Dory’s unreliability, but soon he finds it unbearable. Relaying his frustrations to her, he demands and explanation. Dory, realizing the situation, confesses that her odd behavior is due to ‘short-term memory loss’, but is that truly the case?
Short-term memory is what you are consciously processing. It is limited both in capacity (about 7 items, plus or minus 2) and in duration (about 15-30 seconds). To put it in perspective, you are using short-term memory this very instant to read this blog post. If you did not have short-term memory, you would be unable to process and understand what these letters mean. Not only would you be unable to read, but you also would be unable to hold a conversation or work out math problems.
Now, relating this back to Dory, it is with evident that Dory is perfectly capable of holding a conversation and reading (as seen when she reads “P. Sherman 42 Wallaby Way, Sydney” off of scuba goggles). This means that Dory does have short-term memory and is not impaired in those processes in any way. Though this begs the question that if it is not short-term memory loss that Dory has, then what is it?
This answer can be found when you look more into Dory’s symptoms. Dory is seen on many occasions having a conversation with someone, then abruptly gets distracted and soon cannot remember what they were discussing. Though she forgets some things almost instantly, she can remember long-term events such as her family and her name. Dory can also perform implicit memory tasks that require “unconscious memory” such as swimming in the sea without having to think about it. After researching these symptoms, it is clear that Dory has anterograde amnesia.
Anterograde amnesia “is the loss of the ability to create new memories”. Mainly, it is thought to be due to damage to the hippocampus and the medial temporal lobe. The hippocampus and the medial temporal lobe are both known to be linked with explicit memory (or declarative memory) which are the things we consciously remember. Though long-term memory is by far more complex of a process that it cannot be related to only two brain structures, evidence has been found to prove that these structures are extremely important for this process. The hippocampus and the medial temporal lobe specifically relate to consolidation, or the process of strengthening a memory so you can consciously recall or retrieve when required, this helps turn short-term memories into long-term memories. Thus, when Dory cannot recall events that occurred just moments earlier, it is because her memories never made it to long-term storage, therefore once her memory leaves short term storage, it is immediately forgotten.
At a first glance, Dory’s diagnosis may seem counter intuitive. That Dory, who can only remember a short duration of experiences and thoughts, does not have short term memory loss. I too had fallen into confusion when I first read up on the topic of short term memory loss and realized that Dory’s disorder diagnosis was untrue. Though after further research, the results are clear. Dory does not suffer from short-term memory loss, but she does suffer from of anterograde amnesia.