Explicit Memory: Definition, Types, and Examples
Table of Contents
Explicit Memory Definition
In humans, the major subsets of long-term memory include explicit memory as declarative memory and implicit as non-declarative memory. Explicit memory mainly recalls conscious memory and is known as a system of storage.
The memory can be communicated and recalled thus referred to as declarative memory. For example remembering facts and details, recalling and understanding.
Explicit Memory vs Implicit Memory
The long- term memory is classified as explicit and implicit memory. Explicit memory is also known as conscious memory whereas implicit memory is called unconscious memory. A person’s ability to carry out tasks, respond to stimuli are some examples of implicit memory. We cannot recall this information.
Types of Explicit Memory
There are two major types of explicit memory: episodic memory and semantic memory. The interaction between these categories is considerable and the distinction is not entirely strict. Some other classes of explicit memory include autobiographical and spatial memory.
i. Episodic Memory
The storage and recollecting the first-hand personal experiences is termed episodic memory. For example recalling the events that occurred during a specific occasion, location and time of the occasion, and other details about the occasion is the episodic memory. These memories are more vivid in the case of any significant occasion attached to them.
ii. Semantic Memory
The process of storing factual information is referred to as semantic memory. Just like the episodic memory, this memory also includes facts and figures, definitions, and concepts.
The semantic memory can be voluntarily articulated. The examples include some statements and definitions such as “the mitochondrion is the powerhouse of the cell” etc.
iii. Autobiographical Memory
The combination of episodic and semantic memories is called autobiographical memory. Sometimes the episodic memory is confused with autobiographical memory but according to researchers, they are part of different systems.
As compared to episodic memory the autobiographical occurs over a longer time. It mainly gives an impression about a person and thought to strengthen the events that have happened throughout our lives.
iv. Spatial Memory
A person’s awareness of its surroundings is termed spatial memory or the ability of a person to navigate their way around an area is called spatial memory. The example includes the ability to find our way around our hometown and recall various regions.
Explicit Memory and the Brain
The hippocampus, the prefrontal cortex, and the amygdala are the main areas of the brain that are involved in storing explicit memories.
Hippocampus: The S-shaped neuronal structure found deep within the temporal lobe is called the hippocampus. It is mainly involved in learning, memory strengthening, and spatial navigation. The formation of new explicit memory is also assisted with the hippocampus thus any damage affects the formation of new memories.
Prefrontal Cortex: The frontal lobe of the brain is covered by the prefrontal cortex that implicates personality, decision-making, and social behaviors. The prefrontal cortex also helps in the retrieval of explicit memories. Especially related to semantic memory. To create long-term storage of these memories it works together with the hippocampus.
Amygdalae: The amygdalae are located deep within the brain and have a pair of two almond-shaped structures. It functions along with the hippocampus and helps in regulating emotions, such as anger and fear, and decision-making. It also has a significant role in memory and emotional learning.
It helps mainly to remember an event into long-term memory with a strong emotional component. For example, we probably don’t remember anything about our schedule on May 4th, 2003, but we will likely remember what we were doing on the morning of September 11th, 2001.
Clinical Relevance of Explicit Memory
Alzheimer’s Disease: Half of the cases of dementia accounts for Alzheimer’s disease. The symptoms of the disorder include chronic neurodegeneration that reflects in progressive worsening of explicit memory. The first sign of Alzheimer’s disease includes the deterioration of this type of memory.
It is caused by the formation of amyloid plaques in the brain. The plaques damage neurons and the areas where they are found, also get damaged by these plaques. Alzheimer’s disease most severely affects the hippocampus.
Anterograde Amnesia: The inability to the formation of new memories after a particular event is described as anterograde amnesia. Brain injury or a traumatic event are events that cause anterograde amnesia. In this condition, the memories surrounding the event are not retained but the long-term memories remain intact.
The use of certain drugs and alcohol intoxication can cause acute anterograde amnesia. Usually, in patients with anterograde amnesia, implicit memory is retained that helps them to recall how to perform tasks and learn new ones. For example, they can play a musical instrument and also learn it but cannot recall facts and events.
The Case of Henry Molaison
Henry Molaison is a patient of epileptic fits since childhood. The disorder become so debilitating by his mid-twenties and he became unable to lead a normal life. In 1953, doctors performed a lobotomy to treat his epilepsy and remove some critical structures including the hippocampus, parahippocampus, and amygdalae.
But the procedure made him unable to form new memories. This situation is called a severe form of anterograde amnesia. However, He could learn how to perform new tasks, thus his implicit memory was intact but he could not retain any information.
In his life and even after his death, Henry Molaison became a subject to intense research and was known as H.M. in the neuroscience research community. This situation revealed the working of different parts of the brain and how it controls memory.
