How We Remember/Forget memories

How we remember: 

• Visually: Thinking of the image of the object.
• Acoustically: Thinking or hearing the word of the object.
• Semantically: Thinking of the meaning of the object.

Once a memory has been encoded, a link is created leading to the memory. This link can be triggered by cues of any of the 5 senses (see,touch,hear,taste or smell). This cue can be anything. For example, a toy could remind you of a childhood memory, or a piece of music can remind you of another memory related to it. These memories could link to a particular positive or negative emotion.  

How we forget: 

There are 5 main reasons as to why we forget memories.

1. Retrieval failure:
• Retrieval failure is the most common reason for forgetting. It is the failure to retrieve or recall a memory due to missing stimuli that were present when it was encoded into the memory. These are sometimes temporarily forgotten, they can be remembered if given the proper cue to trigger the memory. 
2. Decay or fading:
• When something new is learned, a trace is used to store the memory. These traces can fade over time if not retrieved or used very often. This is the decay theory that if a memory is not retrieved, it will be lost. This explains the short term memory having memories that are lost, as the storage for the STM is limited. However, due to the long term memory having unlimited storage, the theory does not explain why people forget memories in the LTM. 
• It is known that people often keep memories because of a strong emotional or visual link to the memory they have. If that link is weak, it could fade. The memory itself does not fade but without a link it is unable to be accessed. The link can be kept by constantly remembering it. 
3. Motivated forgetting:
• People often push away any unpleasant thoughts and feelings into their unconscious. This is often to avoid negative feelings or situations so by pushing it away it stops those situations temporarily. They could also want to forget a memory because it is either traumatic or disturbing.
• Motivated forgetting has several defence mechanisms to forget memories. For example, denial, repression and displacement. 
• Denial: The refusal to experience the situation or memory. People often protect themselves from dealing with consequences and pain that comes with accepting that the memory happened. It stops short term pain but in the long run, it will get worse and stop any positive emotions you may have. 
• Repression: Repression is trying to forget the experience altogether. The mind buries the memory in the subconscious, preventing the pain that can happen from knowing the experience happened. This often happens with abuse and other traumatic events. The effects are similar to denial; okay for the short term but will get worse. 
• Displacement: Displacement is transferring the emotions caused by someone onto someone else. The mind believes that the source of the emotions is too risky to confront (e.g. a boss, etc). so you move onto another less risky target. This helps stop the consequences that may happen if you confronted the reason for the emotions but in the process you may hurt someone who is innocent.
4. Interference
• Interference occurs when information gets confused with other information that is stored in the LTM. There are multiple reasons for this; either the memories can compete with one another for storage so some are lost, or cues to triggering memories can be similar so the wrong memory could get retrieved. 
• There are two types of interference: Proactive and Retroactive. 
• Proactive: When any new pieces of information interferes with old information. 
• Retroactive: When any old pieces of information interferes with new information.
5. Physical injury/trauma:
• Some memories can be lost due to physical injury or any trauma to the head. There are two types of amnesia that can happen due to trauma.
• Anterograde amnesia: The inability to remember events that occur after an injury or traumatic event. 
• Retrograde amnesia: The inability to remember events that occurred before an injury or traumatic event.

Sources:
Psychology books.
'Why do we forget things?' article (in evidence folder). 
http://thepeakperformancecenter.com/educational-learning/learning/memory/forgetting/