Types of Memory: Concepts to Research

Memory is the cognitive function that enables us to encode, store, and retrieve information. It is a function essential to our knowledge of the world and daily functioning. In this article, we will go over the different types of memory while discussing examples of research and tasks in order to get hands-on understanding of how experiments are conducted to discover more about the different types of memory.

Memory is typically categorized into sensory memory, short-term memory, and long-term memory, each with distinct characteristics of their own. Let’s dive in!

Sensory Memory

The whole process of remembering starts with information entering the sensory memory, ie what is fed into the five senses. When we come across sensory information (such as sound, touch, smell), a brief storage of it occurs and it's called the sensory memory. These are typically short lived. If attention is given to this sensory information, it gets encoded into the short-term memory (Ciolek & Lee, 2020).

Eventually, aspects of sensory memory will enter into long-term memory, allowing you to hold dear memories of things like the rhythm of your favorite blues song. Let’s dive into the different types of sensory memory:

Iconic Memory

Iconic memory is a subset of sensory memory that is associated with visual data, specifically describing the short-term retention and quick deterioration of visual information. A person with an iconic memory can hold onto an image of a scene or object for a very brief period of time, usually around 250 ms (Kanwar et al., 2023). The word "iconic" is derived from the Greek word "eikōn" (εἰκών) meaning “image” highlighting this type of memory's visual component (Klyukanov & Sinekopova, 2016).

George Sperling's seminal experiment from the 1960s, the partial report paradigm, is a great example of iconic memory. In this experiment, a grid of letters was shown to participants for a brief period of time. After the display vanished, participants were asked to recall either the entire grid or a particular row of letters. Sperling discovered that when cued right after the display, participants could accurately recall the whole grid, indicating a transient storage of the visual information (Sperling, 1960).

In this example below in Labvanced, participants are asked to input the numbers they just saw on the screen in a Digit Span Task:

Import the Digit Span Task to your account or simply try it out in Labvanced.

Echoic Memory

The short-term sensory memory known as "echoic memory" is what enables the auditory system to hold onto sounds and other stimuli for a brief amount of time after the initial stimulus has ended. Echoic memory persists longer than iconic memory and it lasts for around 1 to 2 s. Echoic memory plays a key role in processing and comprehending spoken language. It facilitates the maintenance of an uninterrupted flow of auditory information, enabling people to perceive and understand sound, music, or other types of auditory stimuli (Kanwar et al., 2023; Cope et al., 2023).

The phenomenon known as the "backward masking effect" is a well-known illustration of echoic memory in action. When someone hears a series of sounds and then immediately after that, another sound (a mask) is presented, it can obstruct their perception and memory of the first sound. Even though echoic memory is short-lived, it is essential to our comprehension and interpretation of our auditory surroundings (Edelman & Moyal, 2017).

Haptic Memory

The term "haptic memory" usually describes a type of sensory memory associated with haptics, or the sense of touch. Specifically, haptic memory is the ability to remember touch-related experiences. Haptic memory is a vital component of our whole sensory experience, as it helps us perceive and comprehend the physical world around us. From identifying textures to handling objects, it is involved in many everyday tasks (Shihet al., 2009b).

📌 Publication Spotlight: The role of affective touch in promoting infants’ attention towards complex visual scenes

A study by Carnevali, L., Della Longa, L., Dragovic, D., & Farroni, T. (2024) in Labvanced explored the role of affective touch in enhancing infants' attention towards complex visual scenes, emphasizing the integration of multisensory information in early development. The Labvanced-based study used:

• Task Design: A three-phase experimental task to assess the impact of affective and non-affective touch on infants' attention to visual stimuli.
• Materials: Animated characters (square and triangle) paired with auditory (musical note) and tactile (hand touch) stimuli to create engaging multisensory experiences.
• Data Collection: i) Infants' looking times were recorded during familiarization and visual presentation phases to measure attention and engagement; ii) Video recordings of the sessions allowed for offline coding of infants' responses.

Findings: The researchers found that affective touch (in Phase 1 of the experiment) led to longer looking times during the scenes presentation (phase 2). This shows how haptic experience or memory can play a significant role in modulating infants' visual attention towards complex visual scenes by predisposing them to explore their environment and facilitating sustained attention.

Gustatory Memory

Gustatory memory refers to the memory of taste. The ability to remember a specific food taste is relevant for food intake, but also associative learning. In psychology research, gustatory memory is typically studied in the context of food or taste-aversion and how the taste or previously consumed foods guides future diet-related behaviors (Lim et al., 2022).

Olfactory Memory

Olfactory memory refers to the memory of smell or odor. In the natural world and animal kingdom, smell plays an important role in guiding behavior, helping with survival, and even assisting with spatial navigation (Yang et al., 2021). One recent trend in psychology research is to study olfactory training, ie. smell training with repeated exposure to odorants with the aim of neuroplasticity. This paves way for understanding how olfactory memory intertwines with other cognitive processes, but also for pathological conditions (Vance et al. ,2024).

📌 Publication Spotlight: Comprehension of odor-related language in acquired anosmia

In this study conducted in Labvanced, researchers wanted to assess whether acquired anosmia (the loss of the sense of smell that comes later in life) impacts the comprehension of odor-related language. The researchers administered a series of tasks, in order to get a full picture of odor-related memory in anosmics and controls. Interestingly, the study concluded with no evidence that acquired anosmia impairs the comprehension of odor or taste words, but emotional associations with odor and taste words were altered in anosmics, with more positive ratings. Overall, these findings suggest that language processing may in some cases be independent of the ability to have an olfactory sensory experience (Speed, L. J., Iravani, B., Lundström, J. N., & Majid, A., 2022).

Example of the Lexical Decision Task procedure conducted in Labvanced; Speed, L. J., Iravani, B., Lundström, J. N., & Majid, A., (2022).

Short-term Memory

Short-term memory (STM) refers to the processing of small amounts of information for a short period of time. When we recall a piece of information immediately after it's presented to us, that’s STM in action! In the absence of rehearsal, the information undergoes rapid decay and would thus last for less than ~30 seconds. SRT includes working memory, which helps in performing the process of short term memory storage (Camina & Güell, 2017; Kramer & Stephens, 2014).

Working Memory

Working memory is in charge of manipulating and temporarily storing information. It is the ability to retain information in your mind for a brief period of time so that you can use it for additional processing. For cognitive tasks involving the simultaneous processing of information, like following directions, figuring out difficult problems, and understanding spoken or written language, working memory is crucial (Maricle & Bauman Johnson, 2016).

One of the most common tests used to measure visuospatial short-term and working memory is the Corsi block-tapping test (CBT) (Schaefer et al., 2022).

The example below shows the Corsi block-tapping test administered in Labvanced:

Import the Corsi Block-Tapping task to your account for your next experiment or simply try it out in Labvanced.

Long-term Memory

When information stored in short term memory transfers to long term storage, it’s called long term memory (LTM) and can last for days and even years. LTM involves the processes of encoding, storage, and retrieval of information (Johnson, R. (2014). It has been divided into two broad categories– explicit and implicit memory.

Declarative / Explicit Memory:

Explicit memory, or declarative memory, is the category of memory that includes the deliberate recall of events and facts. It is of two types:

Episodic Memory

A subset of declarative memory that deals with personal experiences and has the capacity to recollect particular experiences or events from a person's past. It is the recollection of individual encounters connected to a specific location and period of time.

Episodic memory is often referred to as ‘autobiographical memory.’ For example, recalling particulars about events, including what happened, where it happened, when it happened, and any feelings or emotions that were connected to it. Episodic memory contains sensory details (details or information perceived through the five senses) that lets us relive an experience (Morè et al., 2020).

Semantic Memory / Autobiographical Memory

This is another subset of declarative long-term memory that includes facts and general knowledge. It covers a vast array of ideas, such as language, reality, and word meanings. Semantic memory is essentially all the acquired knowledge that one has gathered about the world (Binder, J. R., & Desai, R. H., 2011). This includes things like the names of colors, language comprehension, or the capitals of major cities.

Semantic memory is more abstract and general than episodic memory and is not connected to any particular personal events. Compared to episodic memory, which is the memory for specific experiences, semantic memory ability appears to develop earlier in childhood. Studies show that semantic memory tends to stabilize overtime and even increase with advancing age (Martin & Simmons, 2008; Richmond & Burnett, 2022).

Nondeclarative / Implicit Memory

Implicit memory, another name for nondeclarative memory, is a category of long-term memory that is not consciously recalled. This kind of memory includes conditioned responses, skills, habits, and behaviors. A lot of the time, nondeclarative memory is expressed and acquired unconsciously. It further includes the following:

Procedural Memory

Procedural memory is a subset of nondeclarative or implicit memory that includes the formation and maintenance of perceptual-motor skills and habits, like riding a bike or playing a sport! It is responsible for allowing people to take action and make decisions without realizing they are doing so or needing to recall specific details from memory. Procedural memory plays a critical role in our ability to learn and develop motor abilities through practice and repetition. In terms of neurobiology, procedural memory involves stronger connections between synaptic pathways associated with the behavior, resulting in reflexive and unconscious responses (Fogel & Smith, 2011; Mayford et al., 2012).

In a study conducted in Labvanced by Gavard, E. & Ziegler, J.C. (2024), a series of tasks was implemented in order to determine whether statistical learning (a cognitive mechanism that enables patterns to be learned implicitly) could indicate linguistic predictions during reading. One task of relevance here was the serial reaction time task (SRT) which is a classic sequential motor learning task. The researchers administered this in order to get a sense of the participants’ implicit (statistical) learning which is thought to be linked to the procedural memory system.

Experimental design and timing of the SRT task (adapted from Schendan et al., 2003) Gavard, E. & Ziegler, J.C. (2024) in Labvanced.

Associative Memory or Classical Conditioning

Associative memory is the ability to recognize and remember the relationships between seemingly unrelated objects. For example, developing a fear of dogs after being bitten. Individuals possessing this type of memory can retrieve knowledge more through connections than specific cues or details. For example, you might recognize someone you saw on the street from the scent of the perfume at the nearby shopping center (Suzuki, 2008).

📌 Publication Highlight: Associative learning and memory and analogue PTSD symptoms

Friesen, E., et al (2022) set out to determine whether distress and rumination related to the COVID-19 epidemic could influence the development of analogue PTSD symptoms upon participants being exposed to a non-COVID-19-related aversive film clip. The researchers also wanted to investigate if this relationship was mediated by the strength of associative learning (i.e., fear conditioning). The researchers administered their experiment and associative learning task using Labvanced. The image below shows the experimental set up and study procedure. The findings suggest that heightened distress during the COVID-19 pandemic may have strengthened associative learning, leading to increased intrusive memories and rumination in response to an analogue traumatic event.

Illustration of the study procedure conducted in Labvanced.
Note: (A) General study procedure. (B) Procedure of the differential associative learning task. (C) Stimulus presentation in a reinforced CS+ trial during the differential associative learning task. CS+ = conditioned stimulus; US = unconditioned stimulus; Friesen, E., et al (2022).

Non-associative Memory

Non-associative memory, also known as non-associative learning, is learning that does not need stimulus association or pairing. This style of instruction is regarded as the most fundamental and straightforward approach as it relies on behavioral change as a response to a single stimulus. It places more emphasis on acquiring and holding onto distinct components without necessitating connections or linkages between them (Ioannou & Anastassiou-Hadjicharalambous, 2018). Important topics in this domain include, habituation and sensitization. An example of non-associative learning of habituation would be upon living for a while in a busy street, you eventually ‘get used to it’.

Priming Memory

This is an implicit memory effect in which exposure to one stimulus influences responses to another, referred to as "priming" in psychology. It involves activating particular schemas in long-term memory to facilitate the retrieval of relevant information. For example, when an individual is exposed to the color yellow and later asked to quickly name a fruit, it is more likely that they would say the word "banana" rather than "apple" or "grape." This technique of priming is applied in psychology to teach people how to react to certain stimuli or change their behavior. Without the person understanding it, priming influences cognitive function either consciously or unconsciously. Understanding how prior exposure to stimuli might affect behavior and cognitive processes in the present is made easier with the help of priming (Bermeitinger, 2015).

In the image below, a sample stimuli set from a study by Baumann, L., & Valuch, C. (2022) conducted in Labvanced, shows the numerous stimuli used to study the effect of semantic processing and priming in a categorization task. Participants were asked to categorize the prime image (ignoring the target) as either an indoor or outdoor scene. The prime was presented very briefly (50 ms), followed by the target (400 ms maximum). The researchers found that reaction time was significantly faster when the prime and target belonged to the same congruent category (ie., both were outdoor scenes).

Sample set of stimuli used in Labvanced to study priming of scene categorization.
(A-left) Example target stimuli of each context of the outdoor category (A-right) indoor category (B) Top image -left: example prime stimuli for the outdoor category; bottom images -left: target stimuli for the outdoor category for playground; Top image -right: example prime stimuli for the indoor category; bottom images -right: target stimuli for the outdoor category for kitchen;
Baumann, L., & Valuch, C. (2022).

Conclusion

Memory is a complex and multifaceted system. Understanding its forms and different types helps us learn how we retain, process, and recall information, ultimately shaping our learning, perception, interaction and navigation of our daily life in the world!

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