What You Should Know About Your Memory

Memory is fascinating. It’s our personal collection of memories that define who we are and how we feel about the world around us. The continuous creation of memories is what allows us to adapt to our environment and understand what’s happening. When systems of memory aren’t working, it causes serious distress. It’s critical to know the different types of memory and memory stages for understanding how our brains work.

Despite its significance in our lives, most of us aren’t familiar with how our memory works. Here are the essentials that you should know about your memory.

In the scientific view of human memory, there are two main types of memory known as conscious (explicit)1 and unconscious (implicit)2. There are also five distinct subtypes of memory that are defined by what information is stored, and the processes that occur in the brain to form and recall those memories:


Episodic memory, also known as autobiographical memory, is the collection of past personal experiences that occurred at a particular time and place.3 For example remembering a time when you were a child, or thinking about your first job.


Semantic memory stores factual information. It refers to a portion of long-term memory that contains ideas and concepts such as facts, meanings and details about the external world.4 For example, the fact that atoms contain electrons, or how your living room is arranged.


Working memory is a type of memory that allows us to process information. This includes tasks such as understanding immediate surroundings, doing mental math, or interpreting language.5


Procedural memory allows us to remember the steps in a task to perform a skill. It is responsible for knowing how to do things by storing procedures.6 For example, activities such as walking, talking and riding a bike. Procedural memory is an unconscious form of memory––that means we don’t have to consciously think about doing the activity.7


Priming is memory facilitated by prior exposure to something. For example, if I say think about the color yellow, and ask you to name a fruit, odds are higher that you would say “banana”. Priming is an unconscious form of memory.8


Along with two main types and five subtypes of memory, there are distinct memory stages. There are debates about how long each of these stages last, but generally you can think of these in the following way:


Sensory memory is the first stage of memory from the five senses, it holds information for less than a second in order for your brain to process an incoming stimulus.9


Short-term memory is used to remember information for seconds to minutes.10


Intermediate-term memory is for remembering events between minutes to hours.11


Long-term memory is for remembering events between hours to days and beyond.12


When it comes to Alzheimer’s disease and common forms of dementia, typically short and intermediate-term memory is affected first. A common progression for Alzheimer’s disease is for an individual to forget more recent memories and be able to recall and process more distant memories as if they happened just a short time ago. For these individuals, the formation of memories, also known as memory consolidation, tends to be difficult or impossible.

MemTrax focuses on measuring short-term episodic memory for three key reasons.

First, measuring short-term episodic memory pinpoints the type of memory that is commonly affected by Alzheimer’s disease. Commonly, individuals with Alzheimer’s disease are unable to store and recall events that have happened more recently.13 Dr. Wes Ashford designed MemTrax specifically to identify indicators of Alzheimer’s disease.

Second, targeting this type of memory allows MemTrax to be a relatively quick assessment because it is testing the ability to recall information from seconds to minutes ago.

Third, focusing on episodic memory allows MemTrax to be more repeatable over time. The large database of images that we have along with randomized ordering means virtually no two MemTrax tests will be the same. This helps reduce what are known as practice effects, or getting better at a task through repeated exposure to it. Practice effects often interfere with the reliability of cognitive assessments.14

By using MemTrax regularly, you can detect changes in your episodic memory and understand if you need to make changes to your lifestyle in order to protect your brain health.


1 Ullman MT. Contributions of memory circuits to language: the declarative/procedural model. Cognition 2004; 92: 231–70.

2 Schacter, D. L. (1987). “Implicit memory: history and current status” (PDF). Journal of Experimental Psychology: Learning, Memory, and Cognition 13: 501–518.

Schacter, Daniel L., Gilbert, Daniel T., and Wegner, Daniel M. “Semantic and episodic memory”. Psychology; Second Edition. New York: Worth, Incorporated, 2011. 240-241. Print

4 McRae, Ken; Jones, Michael (2013). “Semantic Memory”. In Reisberg, Daniel. The Oxford Handbook of Cognitive Psychology. New York, NY: Oxford University Press. pp. 206–216.

5 Squire, L.R. (2004). “Memory systems of the brain: A brief history and current perspective”. Neurobiology of Learning and Memory 82: 171–177.

6 Bullemer, P.; Nissen, MJ.; Willingham, D.B. (1989). “On the Development of Procedural Knowledge”. Journal of Experimental Psychology: Learning, Memory and Cognition 15 (6): 1047–1060.

7 Postle BR (April 2006). “Working memory as an emergent property of the mind and brain”. Neuroscience 139 (1): 23–38.

8 Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003), page 453-454, 457.

9 Balota, David A., Patrick O. Dolan, and Janet M. Duchek. “Memory changes in healthy older adults.” The Oxford handbook of memory (2000): 395-409.

10 Cowan, Nelson. “Activation, attention, and short-term memory.” Memory & Cognition 21.2 (1993): 162-167.

11 Norman, Donald A., and Daniel G. Bobrow. “Descriptions: An intermediate stage in memory retrieval.” Cognitive Psychology 11.1 (1979): 107-123.

12 Atkinson, R.C.; Shiffrin, R.M. (1968). “Chapter: Human memory: A proposed system and its control processes”. In Spence, K.W.; Spence, J.T. The psychology of learning and motivation (Volume 2). New York: Academic Press. pp. 89–195.

13 Bäckman L, Jones S, Berger AK, Laukka EJ, Small BJ. Multiple Cognitive Deficits During the Transition to Alzheimer’s Disease. Journal of Internal Medicine. 2004;256(3):195–204. doi:10.1111/j.1365-2796.2004.01386.x. PMID 15324363.

14 Goldberg, Terry E. et al. Practice effects due to serial cognitive assessment: Implications for preclinical Alzheimer’s disease randomized controlled trials. Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, Volume 1 , Issue 1 , 103 – 111.

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