The Many Types of Memory

At a job interview, the interviewer asks you to name some of your former clients. You rattle off a list but aren’t able to recall the name of a big-ticket one. You hem and haw, scouring your memory, hoping the answer pops up. As you exit the interview and ride down the elevator, the name strikes you. Aargh! If only this happened a few minutes ago. 

During a meeting, a colleague mentions that you didn’t share last month’s sales figures at the meeting. You get miffed as you’re sure you did. Instead of contradicting your colleague, you open up your laptop to access the presentation. Nothing like solid proof, you console yourself. As you run through the slides, you realize that the one with the sales figures is missing. Fortunately, you kept quiet. 

A colleague calls you from another floor asking how to change the printer cartridge. You’ve done this a gazillion times but when you try explaining over the phone, you’re not really sure if the switch to open the cartridge hatch is to the left or right of the printer. As you fumble with your instructions, you decide it’s more efficient if you just run up and show him how to do it. The moment you see the printer, your hands know exactly what to do. Yet, you struggled to explain the steps over the phone.  

Memory is central to human functioning and a core facet of our identities. Over the past few decades, cognitive psychologists and neuroscientists have made great strides in understanding the science behind this mystifying faculty. In Why We Forget & How to Remember Better, two researchers, Andrew Budson and Elizabeth Kensinger, unpack the architecture of memory. In this article, I will explain the structure and types of memory and in next month’s issue, I will provide tips and strategies to help you remember better, both in your professional and personal lives. 

First, memory is not a unitary faculty but is comprised of a number of systems, with each being subserved by distinct neural circuitry and processing “different types of information.” Budson and Kensinger explain that memory may also be classified in multiple ways. One way is based on the “timeframe in which they operate.” While short-term memory is online from seconds to minutes, long-term memory can span a timescale from minutes to years.  

Short-term memory may be further subdivided into sensory and working memory. The former refers to fleeting sensations, whether visual, auditory, tactile, olfactory or gustatory. Whether it’s the sound of your phone ringing or the smell of a freshly baked cake, these sensations usually don’t last more than three seconds after the stimulus has been removed. Sometimes, memories of these sights, sounds and smells may make their way to working or long-term memory. 

Our working memory, sometimes called our visuo-spatial sketchpad, allows us to keep information “in mind” so that we may perform manipulations on them. This could involve merely repeating an OTP number before you enter it, adding a set of numbers mentally or remembering that you parked your car in Basement 1 of the mall. 

Long-term memory is categorized into implicit and explicit memory. As the names suggest, implicit memory does not require conscious awareness, whereas for explicit memory requires that we consciously attend to the information or contents both in the learning and retrieval phases. 

Implicit memory is further subdivided into three sub-systems. Procedural memory is involved in remembering motoric movements. Also known as “muscle memory,” this subsystem is activated when you learn a new dance routine, ride a bike or type on your laptop. The second subsystem subserves priming. Suppose, you’re doing a word puzzle on your way to work on your phone when it rings. You take the call and then return to the puzzle that requires you to think of a synonym for ‘ring.’ Words like ‘buzz,’ ‘ping’ and ‘chime’ come to you. On the other hand, when you see the word ‘ring’, you happen to glance at your engagement ring. Words like ‘band’, ‘coil’ or ‘jewel’ pop into your mind. Of course, you may not be aware why one set of words crops us in one instance and a completely different set in another. That’s the effect of priming. 

Another form of implicit memory involves classical conditioning that most students encounter in high-school textbooks. First described by Russian physiologist, Ivan Pavlov, this involves pairing an unconditional stimulus (food) with a conditioned one (bell) to elicit a response (salivation). With a sufficient number of pairings, the conditioned stimulus evokes the response on its own. Budson and Kensinger point out that this kind of memory is especially relevant during severe stress and may explain why some people succumb to post-traumatic stress disorder (PTSD). 

The other category of long-term memory is explicit or declarative memory. When we use the term ‘memory’ in everyday language, this is the kind of memory that most people refer to. Explicit memory is further divided into episodic and semantic memory. The former refers to your memory of life events, both trivial and profound. This could include what you had for breakfast this morning, how you felt on your high-school graduation day, the way your partner proposed to you etc. Semantic memory, on the other hand, refers to your storehouse of facts such as the function of a barometer, the gases that comprise the atmosphere or the meaning of ‘mesmerize.’ 

Now that you’ve read about the main memory systems and their classification, do you want to test your memory for what you’ve just read? Try answering the following questions. 

1. Answering questions immediately after reading a passage involves: 

  1. Short-term memory 
  2. Episodic memory 
  3. Declarative memory 
  4. Procedural memory 

2. Riding a bike involves: 

  1. Working memory 
  2. Short-term memory 
  3. Procedural memory 
  4. Declarative memory 

3. Which of the following are implicit forms of memory? 

  1. Priming 
  2. Procedural memory 
  3. Classical conditioning 
  4. All of the above 

4. Changing a printer cartridge involves: 

  1. Priming 
  2. Procedural memory 
  3. Working memory 
  4. Classical conditioning 

In the next issue, I will discuss what you can do to strengthen these different memory systems. 

Answers to the questions are:

  1. 1
  2. 3
  3. 4
  4. 2

About the Author 

Aruna Sankaranarayanan is a psychologist & writer. She is the author of Zero Limits: Things Every 20-Something Should Know. She blogs at

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