Here are four possible reasons for why we may not be able retrieve something we have previously encoded and stored:

• Decay – it is possible that the information has dissolved over time and is lost forever. Much like the information in our sensory information decays rapidly, information we do not access frequently might be lost permanently.

• Interference – sometimes it is hard to encode information correctly or to recall it efficiently because our brain is processing something else at the same time. One thing interferes with the other. For example, you might not be able to recall something that you studied just before hearing some terrible news – all of the thinking you did about the bad news might interfere with the information you just encoded.

• Insufficient priming – the memory might be stored correctly, but you may not have enough activation to locate it and move it from long term to short term memory. For example, if you are trying to remember someone’s name, it might be helpful to run through the letters in the alphabet. Once you get to “S”, you might have triggered the memory by adding in the right prime to your efforts.

• Disorganization – it is also possible that the information is stored, but that you cannot find it due to some error in the manner the information was organized in storage. So it might not be gone, it might just be hard to access. Have you even tried to remember something, and then all of a sudden minutes or even hours later, it just pops into mind?

Amnesia is a condition where there is a loss of memory. There are two general categories of amnesia:

Retrograde amnesia refers to the inability to remember things prior to the onset of memory loss. Someone with a head injury may have no memory of a couple hours prior to the accident, while someone else might forget their name or identity, but is perfectly able to form new memories. In some cases people with such a condition might go on to form completely new lives.

Anterograde amnesia refers to an inability to form new memories, even though memories from the past remain intact. Individuals with Alzheimer’s disease may remember childhood and their life several years ago, but may not remember who their family members are today or what they did five minutes ago. Watch the real story of one man with anterograde amnesia:

Optional Review Activity: Watching the following movie clips or trailers and decide which type of amnesia the character has -- anterograde or retrograde?

A) Memento (http://youtu.be/0vS0E9bBSL0)

B) 50 First Date (http://youtu.be/ErjP5xMTc8I)

C) Borne Identity (http://youtu.be/FpKaB5dvQ4g)

D) The Long Kiss Goodnight (https://youtu.be/oDuma1M09B0) 

E) Dory (the blue fish) in Finding Nemo (https://youtu.be/tESffhWs8l0)

F) Overboard (https://youtu.be/HH6OuDYKWNE)

Back to Unit 02 - Cognition, Intelligence & Memory