LONG TERM MEMORY
DECLARATIVE/EXPLICIT VERSUS NON-DECLARATIVE/ IMPLICIT MEMORIES
Long-term memory (LTM) can be divided into two types:
Explicit/ Declarative and Conscious.
Implicit/Non-Declarative and Unconscious.
Declarative memory encompasses memories that can be consciously recalled and articulated, such as facts, knowledge, and personal experiences. This form of memory allows individuals to "declare" what they know, whether it's recounting a past event, such as describing a birthday celebration or recalling factual knowledge, such as naming the capital of a country. Declarative memory derives from this ability to retrieve and verbalise stored information explicitly.
Episodic and semantic memory falls under declarative memory as they involve explicit recall and deliberate retrieval. For example, episodic memory allows you to recall specific personal experiences vividly. In contrast, semantic memory enables you to share general facts or concepts without being tied to any particular time or place.
In contrast, non-declarative memory operates unconsciously, allowing individuals to retrieve information or perform actions without deliberate effort. For instance, riding a bike relies on procedural memory, a form of non-declarative memory that stores motor skills and habits. Unlike declarative memory, procedural memory cannot easily be articulated; if asked to explain how you ride a bike, you might struggle to describe the intricate processes, such as the exact coordination of muscles or balance required to keep the bike in motion. Instead, you act automatically, demonstrating the difference between declarative and non-declarative systems.
This distinction highlights long-term memory's dual nature and underscores declarative memory's specificity in enabling conscious, explicit access to knowledge and experiences.
EXPLICIT OR DECLARATIVE MEMORY - “knowing that”
Memories you must work to remember consciously are known as explicit memories, such as consciously recalling items on your shopping- list. Explicit memory is also referred to as conscious or automatic memory, as this kind of memory is both mindful and intentional.
Explicit memory is often called declarative memory since you can declare (say) what you remember. This is because explicit memories can be verbally explained, e.g., what you did at the party, a book review, or the Capital of Ghana.
There are two types of explicit/declarative memory: semantic and autobiographical/episodic.
KEYWORDS: DECLARATIVE, CONSCIOUS, KNOWING THAT, EXPLICIT AND INTENTIONAL
IMPLICIT OR NON-DECLARATIVE MEMORY - knowing how.”
Memories you remember unconsciously, unintentionally, and effortlessly are known as implicit conscious or automatic memories.
Implicit memory is also often called non-declarative since you cannot consciously bring it into awareness or describe it. It is a previously learned motor skill, usually, e.g., talking, writing, bike riding, walking, swimming, etc. Implicit memories are often procedural and focused on the step-by-step processes that must be performed to complete a task. We call it muscle memory in animals.
Where explicit memories are conscious and can be verbally explained, implicit memories are usually non-conscious and not easily articulated. Try describing to someone how you swim or ride a bike.
There is only one type of implicit/non-declarative memory: procedural.
KEYWORDS: NON-DECLARATIVE, UNCONSCIOUS, KNOWING HOW IMPLICIT AND UNINTENTIONAL
TYPES OF LONG-TERM-MEMORY
EPISODIC MEMORY, ALSO KNOWN AS AUTOBIOGRAPHICAL
WHAT IT IS:
Episodic memory recalls personal experiences or events, including what happened, where, and when. These memories are tied to specific moments and often include associated emotions and contextual cues.
EXAMPLES:
Remembering your last birthday party.
Recalling the day you passed your driving test.
CHARACTERISTICS:
Autobiographical: Episodic memories are linked to personal experiences.
Time-stamped: They involve a clear sense of when events occurred.
Contextual: These memories include emotions and environmental details.
BRAIN AREAS INVOLVED:
Hippocampus: Critical for forming and consolidating episodic memories.
Prefrontal Cortex: Plays a role in retrieving episodic information
EPISODIC consists of our thoughts or experiences and our recollections of them. Episodic memories are usually based on events in people's lives; however, over time, they move over to Semantic memory as the event’s association diminishes and the memory becomes “knowledge” based. The emotions present when the memory is coded determine the strength of episodic memories. Traumatic life events may be recalled better due to their strong emotional attachment, and it is believed that episodic memory helps us distinguish between our imagination and actual events. The brain's pre-frontal cortex is linked to the initial coding of episodic memories and consolidation and storage associated with the neocortex.
SEMANTIC MEMORY
WHAT IT IS:
Semantic memory stores general knowledge and facts about the world. Unlike episodic memory, it is not tied to specific personal experiences, times, or places.
EXAMPLES:
Knowing that Paris is the capital of France.
Understanding the meaning of words like "democracy" or "psychology."
CHARACTERISTICS:
Abstract: Semantic memories are unrelated to particular events or experiences.
Shared: Many people possess the same semantic knowledge.
Timeless: These memories are not linked to specific points in time.
BRAIN AREAS INVOLVED:
Temporal Lobe: The anterior temporal cortex is central to storing semantic knowledge.
SEMANTIC MEMORY contains the knowledge, facts, concepts, and meanings the individual has learned, e.g., the capital of France is Paris. Semantic memory may also relate to how particular objects work, their functions, appropriate behaviour in situations or abstract concepts such as language or mathematics. The strength of semantic memory is positively correlated with the strength of processing when coding with semantic memories lasting longer than episodic memories. Semantic LTM is linked to episodic LTM, with semantic memories formed based on occurring experiences. Therefore, episodic memory underpins semantic memory, with episodic-based experiences moving over to semantic memory over time. Semantic coding is mainly associated with the frontal and temporal lobes, with mixed opinions on semantic LTM; some argue the hippocampus is involved, while others believe several brain parts play a role.
PROCEDURAL MEMORY
WHAT IT IS:
Procedural memory is the ability to perform tasks and actions without consciously thinking about the steps involved. It is responsible for learning and retaining motor skills, habits, and routines through repetition and practice. Unlike declarative memory, procedural memory operates unconsciously, enabling automatic performance of well-practised activities.
EXAMPLES:
Riding a bike.
Playing a musical instrument, such as the piano.
Typing on a keyboard without looking at the keys.
CHARACTERISTICS:
Implicit: Procedural memory does not require deliberate recall or awareness of the memory process.
Skill-based: It involves motor skills and habits rather than factual or autobiographical knowledge.
Automatic: Once learned, tasks can be performed effortlessly and without conscious thought.
BRAIN AREAS INVOLVED:
Cerebellum: Plays a central role in motor coordination and skill learning.
Basal Ganglia: Critical for habit formation and procedural learning.
Motor Cortex: Involved in executing learned motor activities
PROCEDURAL MEMORY is skill-based memory focused on recalling how to do something, i.e. swimming, reading or cycling and does not require conscious thought. Procedural memories are usually learnt through repetition and practice. Language is believed to be a procedural memory as it helps individuals speak using the correct grammar and syntax without consciously giving this thought. Procedural LTM is linked to the neocortex brain areas within the primary motor cortex, cerebellum and prefrontal cortex. This is different from declarative memory stores as they do not rely on the hippocampus to function.
EPISODIC AND SEMANTIC LONG-TERM MEMORY (TULVING, 1972)
Tulving (1972) challenged the view that long-term memory (LTM) is a single, unified store, proposing instead that it consists of distinct subsystems that handle different types of information. Earlier models, such as the multi-store model (MSM), treated LTM as a homogenous system, but Tulving argued that this oversimplified the complexity of human memory. His theory gained support from numerous case studies in which individuals with brain damage exhibited impairments in specific aspects of LTM while retaining other forms, providing clear evidence that LTM is not a singular entity. Tulving identified two key types of declarative memory—episodic memory and semantic memory—each serving distinct purposes and characterised by unique functions.
EVALUATION OF TULVING’S MODEL
SUPPORT FOR EPISODIC AND SEMANTIC MEMORY
COGNITIVE NEUROSCIENCE: NEUROIMAGING EVIDENCE
Functional neuroimaging techniques, such as PET and fMRI scans, show distinct activation patterns for episodic and semantic tasks.
Episodic Memory: Activates the hippocampus and prefrontal cortex.
Semantic Memory: Engages the anterior temporal lobe.
COGNITIVE NEUROPSYCHOLOGY (CASE STUDIES): NEUROIMAGING EVIDENCE
Kent Cochrane (KC): Demonstrated an apparent dissociation between episodic and semantic memory. While KC could recall factual information (semantic memory), he had no recollection of personal experiences (episodic memory), supporting the idea that these are separate systems.
Further support for semantic and episodic memory being separated comes from Vicari et al. (2007). A case study of a young girl (CL) who suffered brain damage after the removal of a tumour found deficiencies in the ability to create new episodic memories. However, she could still develop semantic memories supporting the theory that they are separate.
Lastly, Clive Wearing had severe episodic memory impairment; he could not remember past autobiographical events in his life. However, he retained semantic knowledge—he could recall factual information, such as what objects were, the meanings of words like "son" and "daughter," and general knowledge about the world. This supports the distinction between the two types of declarative memory because it demonstrates that while episodic memory (autobiographical recall) was impaired, semantic memory (general factual knowledge) remained intact, highlighting their independence as separate systems within declarative memory.
Overall, research evidence supports the case for three different LTM stores. Brain scans have shown three distinct areas being active with the hippocampus and other parts of the temporal lobe, such as the frontal lobe associated with episodic memory. Semantic memory has been associated with activity in the temporal lobe, while procedural memory is related to the cerebellum and motor cortex.
This supports theories for three distinct stores of long-term memory. Case studies such as HM (Milner 1962) support the case for distinctively different procedural and declarative memory stores. HM could not form episodic or semantic memories due to the destruction of his hippocampus and temporal lobes; however, he could form procedural memory by learning to draw figures by looking at their reflection (mirror drawing). However, he could not recollect how he learned this skill, supporting the case for different stores between “knowing how” to do something and semantic knowledge-based or experience-based (episodic) memories.
A weakness of case studies is that they are based on a single individual, making it difficult to generalise the findings to the broader population as deficits in memory may be unique to this one person.
TYPES OF LONG-TERM MEMORY EVALUATION
Research evidence supports the case for three different LTM stores. Brain scans have shown three distinct areas being active with the hippocampus and other parts of the temporal lobe, such as the frontal lobe associated with episodic memory. Semantic memory has been associated with activity in the temporal lobe, while procedural memory is related to the cerebellum and motor cortex.
This supports theories for three distinct stores of long-term memory. Case studies such as HM (Milner 1962) support the case for distinctively different procedural and declarative memory stores. HM could not form episodic or semantic memories due to the destruction of his hippocampus and temporal lobes; however, he could form procedural memory by learning to draw figures by looking at their reflection (mirror drawing). However, he could not recollect how he learned this skill, supporting the case for different stores between “knowing how” to do something and semantic knowledge-based or experience-based (episodic) memories.
A weakness of this study is that it is based on a single individual, making it difficult to generalise the findings to the broader population as deficits in memory may be unique to this one person.
Another major weakness in theories for long-term memory is the lack of research into brain areas involved in procedural memory. Case studies of individuals with brain damage that affects procedural but not declarative memory are needed to understand this better. However, such cases are sporadic. Therefore, we cannot conclusively say that the procedural memory store is fully understood in any detail to generalise such a theory.
CRITICISMS OF TULVING’S MODEL
The case of Clive Wearing offers another critical insight into long-term memory: Clive could still play the piano, which is neither episodic nor semantic. Playing the piano is an automatic and unconscious skill, not easily articulated or “declared.” For instance, explaining in words how to precisely position your fingers on the keys, how much pressure to apply, or how to seamlessly transition between chords is almost impossible. These actions are deeply ingrained and performed without conscious thought. Despite profound episodic memory impairment, Clive’s ability to play the piano provides compelling evidence for procedural memory as a separate system within long-term memory.
One limitation of Tulving’s 1972 model is its exclusive focus on declarative memory systems (episodic and semantic), neglecting non-declarative memory, such as procedural memory. Procedural memory, which enables skills like riding a bike or playing an instrument without conscious recall, was formally identified as a long-term memory system in the 1980s by researchers like Larry Squire.
Although Tulving later acknowledged procedural memory in his subsequent work, its omission from the original model underscores its narrow focus on consciously accessible memories. This reflects an incomplete understanding of long-term memory’s complexity at the time, particularly regarding the role of unconscious memory processes.
INTERDEPENDENCE OF EPISODIC AND SEMANTIC MEMORY
Critics argue that, as Tulving initially proposed, episodic and semantic memory are not independent systems. Instead, there is a dynamic and reciprocal relationship between the two. Semantic knowledge often originates from episodic experiences, with repeated personal encounters contributing to the abstraction of general knowledge. For example, encountering different breeds of dogs over time leads to the semantic understanding of what a "dog" is, including its characteristics and behaviours.
Moreover, episodic memory often relies on semantic knowledge for context and meaning. For instance, recalling a specific childhood visit to a zoo might draw on semantic information about the types of animals present or the general concept of a zoo. This interdependence blurs the boundaries between the systems and raises questions about whether they function as entirely distinct processes.
Neuroimaging evidence supports this interplay, showing overlapping brain regions involved in episodic and semantic tasks. While the hippocampus and prefrontal cortex are more active in episodic recall, the anterior temporal lobe—a region associated with semantic memory—frequently engages in episodic tasks. This overlap challenges the strict separation proposed by Tulving and highlights the interconnectedness of memory processes.
The interdependence also has practical implications for memory impairments. For example, conditions such as Alzheimer's disease, which primarily affects episodic memory in its early stages, can eventually lead to semantic memory deficits as the disease progresses. This progression underscores how the systems interact and depend on one another for optimal functioning.
While Tulving's distinction between episodic and semantic memory was groundbreaking, the evidence for their interdependence suggests that they are not entirely discrete. Instead, they represent interconnected facets of a broader memory system, working together to support learning, recall, and the construction of meaning in human cognition.
APPLICATIONS TO REAL LIFE
APPLICATIONS IN DIAGNOSIS AND EDUCATION
Tulving’s distinction between episodic and semantic memory has had profound implications for understanding and diagnosing memory-related conditions. For instance, Alzheimer’s disease often begins with impairments in episodic memory. Patients may struggle to recall recent events, such as forgetting conversations or losing track of daily activities. In contrast, their semantic memory (general knowledge, such as recognising objects or knowing the meaning of words) may initially remain intact. This pattern is consistent with Tulving’s model, which identifies episodic and semantic memory as separate systems.
In contrast, semantic dementia, a form of frontotemporal lobar degeneration (FTLD), primarily affects semantic memory. Patients with this condition lose knowledge of facts and concepts. For example, they may forget the names of everyday objects, such as calling a "dog" an "animal," or be unable to identify familiar landmarks, even while their episodic memory remains relatively preserved in the early stages. These distinct patterns of memory loss support the validity of Tulving’s differentiation between episodic and semantic memory systems, demonstrating their relevance in clinical settings.
In education, the distinction has informed strategies for memory enhancement. For example, focusing on episodic memory might involve creating vivid, personal learning experiences, such as storytelling or real-life applications, to aid recall. Conversely, teaching methods aimed at semantic memory often rely on repetition and the organisation of facts to strengthen general knowledge. Understanding these differences allows educators to tailor techniques to the type of memory they wish to enhance.
DIAGNOSING SEN AND BEHAVIOURAL CONDITIONS THROUGH MEMORY IMPAIRMENTS
EPISODIC MEMORY IMPAIRMENTS
AUTISM SPECTRUM DISORDER (ASD)
Individuals with ASD often struggle with recalling autobiographical events, which affects their ability to form coherent narratives or imagine future scenarios.
POST-TRAUMATIC STRESS DISORDER (PTSD)
Episodic memories can become fragmented or intrusive, with individuals vividly recalling sensory details of trauma but failing to construct coherent narratives.
ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD)
People with ADHD may show impairments in episodic memory due to difficulties with attention and working memory, affecting their ability to recall specific past events.
SEMANTIC MEMORY IMPAIRMENTS
DEVELOPMENTAL LANGUAGE DISORDER (DLD)
DLD can involve deficits in recalling and using factual knowledge, such as word meanings, impacting language acquisition and communication.
DYSLEXIA
Some individuals with dyslexia may exhibit semantic memory weaknesses, struggling to retain word meanings or general knowledge, exacerbating reading comprehension difficulties.
OBSESSIVE-COMPULSIVE DISORDER (OCD)
Semantic memory impairments may arise in OCD, particularly with difficulties in categorising and recalling general knowledge due to overreliance on repetitive thought patterns.
LONG-TERM-MEMORY QUESTIONS
Psychologists conducted a case study of Patient X, an individual who developed severe amnesia following a car accident. Patient X has difficulty storing new long-term memories, though his short-term memory and memory for events before the accident are unaffected.
The same psychologists experimented with Patient X, where he was tasked with tracking a rotating disc daily for a week. It was found that Patient X’s performance on the task improved with practice, though he had no recollection of ever having done the task and could not remember the names of the psychologists who experimented.
Concerning the experiment involving Patient X, outline two types of long-term memory. Four marks
Discuss two differences between the types of long-term memory you outlined in your answer to part 1. 4 marks.
