Human memory is an important concept in cognitive psychology and neuroscience. Our brain is actively engaged in functions of learning and memorization. Generally, human memory has been classified into 2 groups: short-term/working memory, and long-term memory. Using different memory paradigms and brain mapping techniques, psychologists and neuroscientists have identified 3 memory processes: encoding, retention, and recall. These processes have been studied using EEG and functional MRI (fMRI) in cognitive and neuroscience research. This study reviews previous research reported for human memory processes, particularly brain behavior in memory retention and recall processes with the use of EEG and fMRI.
what causes those memories to stick around and not be wiped away from that whiteboard? According to a one study from MIT, it might simply be how meaningful an image is and if we can connect it to other knowledge. If you can connect that image to something else, it increases the chances you’ll remember it later. Like learning, memory is all about context. This is why, as The Atlantic points out, pattern recognition is key. Essentially, the more connections a new memory has to knowledge you have, the more likely it is you’ll remember that information. The same basic process seems to happen with most memories.
Sensory memory holds sensory information less than one second after an item is perceived. The ability to look at an item and remember what it looked like with just a split second of observation, or memorization, is the example of sensory memory. It is out of cognitive control and is an automatic response. With very short presentations, participants often report that they seem to “see” more than they can actually report. The first experiments exploring this form of sensory memory were conducted by George Sperling (1963)using the “partial report paradigm”. Subjects were presented with a grid of 12 letters, arranged into three rows of four. After a brief presentation, subjects were then played either a high, medium or low tone, cuing them which of the rows to report. Based on these partial report experiments,Sperling was able to show that the capacity of sensory memory was approximately 12 items, but that it degraded very quickly (within a few hundred milliseconds). Because this form of memory degrades so quickly, participants would see the display but be unable to report all of the items (12 in the “whole report” procedure) before they decayed. This type of memory cannot be prolonged via rehearsal.
Short-term memory is also known as working memory. Short-term memory allows recall for a period of several seconds to a minute without rehearsal. Its capacity is also very limited: George A. Miller (1956), when working at Bell Laboratories, conducted experiments showing that the store of short-term memory was 7±2 items (the title of his famous paper, “The magical number 7±2”). Modern estimates of the capacity of short-term memory are lower, typically of the order of 4–5 items; however, memory capacity can be increased through a process called chunking. For example, in recalling a ten-digit telephone number, a person could chunk the digits into three groups: first, the area code (such as 123), then a three-digit chunk (456) and lastly a four-digit chunk (7890). This method of remembering telephone numbers is far more effective than attempting to remember a string of 10 digits; this is because we are able to chunk the information into meaningful groups of numbers. This may be reflected in some countries in the tendency to display telephone numbers as several chunks of two to four numbers.
The storage in sensory memory and short-term memory generally has a strictly limited capacity and duration, which means that information is not retained indefinitely. By contrast, long-term memory can store much larger quantities of information for potentially unlimited duration (sometimes a whole life span). Its capacity is immeasurable. For example, given a random seven-digit number we may remember it for only a few seconds before forgetting, suggesting it was stored in our short-term memory. On the other hand, we can remember telephone numbers for many years through repetition; this information is said to be stored in long-term memory.
While short-term memory encodes information acoustically, long-term memory encodes it semantically: Baddeley (1966) discovered that, after 20 minutes, test subjects had the most difficulty recalling a collection of words that had similar meanings (e.g. big, large, great, huge) long-term. Another part of long-term memory is episodic memory, “which attempts to capture information such as ‘what’, ‘when’ and ‘where'”. With episodic memory, individuals are able to recall specific events such as birthday parties and weddings.
It’s not just traumatic events that cause our memories to flake out. One study in The Journal of the Association for Psychological Science points out that simply recalling memories enhances and distorts them. Which is to say, when you remember something you’re actively changing it. In part this has a lot to do with a wide variety of memory biases that color the ways we remember. From the positivity effect where we tend to remember the positive over the negative to the egocentric bias where we remember ourselves as being better than we are, we’re constantly changing memories in a way that benefits how we view ourselves. Which is to say, trusting your own memory isn’t always the best idea.
For example, one study published in The Journal of Experimental Psychology showed that we tend to think we’ll remember something important more than we will. This is essentially when you don’t write down a brilliant idea because it’s good you’ll never forget it, and then you immediately forget what it was. It’s happened to the best of us, and it’s because we’re overly confident in our ability to remember.
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