How to better memory, from a cognitive perspective
Normally I discuss behavioral processes such as memory in a purely neurobiological manner, but as memory is such a complex phenomenon, here I revert to cognitive explanations to suggest mechanisms of improving memory.
Firstly, improving one's memory would depend upon how and why one is forgetful.
Do they have brain abnormalities?
Smaller hippocampal regions?
Undiagnosed brain damage?
Elevated cortisol levels?
Lack of sleep?
Or are they really not forgetful, but just think they're forgetful?
If you belong to the first category, it would be near-impossible to genuinely improve your memory without some form of medical aid. In the case of hippocampal damage, memory is largely unretrievable - unless you possibly undertake a form of experimental stem cell treatment for neural rejuvenation. It is possible to, also, use developing cortisol inhibitors if your memory is due to elevated cortisol.
Assuming none of the above apply to you, the next most obvious would be a lack of sleep. Sleep is essentially the time when glial cells “clean up” metabolic wastes released from neurons, via phagocytosis and other related mechanisms. Disrupted sleep would contribute to a build-up of toxic by-products in the cerebral fluid (i.e, around the neurons in your brain), consequently affecting speed of neural transmission and ultimately, memory. (The overall theories regarding sleep and memory are much more detailed, but unhelpful for the purpose of this answer). The underlying idea is, if you are forgetful, re-evaluate your sleep duration.
The last option is interesting; I did not ask it as a trick question in any manner. Essentially, what are you, specifically, having trouble forgetting? There are several cognitive hypotheses to memory.
Let’s first look at semantic recall. There is the multi-store memory model by Atkinson and Shiffrin, which suggests that your loss of memory may be due to
(a) not paying enough attention to the input material,
(b) not rehearsing the information enough.
Assuming you possibly are not following the two above, I would definitely recommend paying careful attention to information, and rehearsing often.
Perhaps a referral to the widely known “forgetting curve” will help. In the 1880s, Ebbinghaus’ experiments led to a general ‘rule’ as to how information is lost over time. Essentially, input must be revised regularly initially, and then decreasingly less often to retain it into your long-term memory. This curve is by no means perfect, and there have been mild criticisms, but it is a good general rule of thumb to follow/consider.
However, simply attention and rehearsal may not resolve all problems. What if you’ve been following the above, and yet you remain forgetful?
The Levels of Processing theory proposes that, for one, it is essential to understand information being learnt - otherwise significant rehearsal will not yield any substantial results. Thus, it could be possible that you are not semantically processing the information enough and thus don’t understand it, which may be affecting your ability to recall it.
However, that’s only for certain types of recollection. What if you wish to improve your auditory, visual and semantic recall?
The Working Memory Model by Baddeley and Hitch proposes that,, depending on your memory, you may find difficulty in recalling different types of information.
Essentially, what it shows is, don’t try to use the same processing system at once - for example, do not listen to Taylor Swift while reading a book. This is because both acts use your phonological loop (relating to language). Thus, the music will hinder your ability to read your book and recall what you have read. However, you can watch an educational video with audio - this is because they use two different processing systems simultaneously - your phonological loop and your visuospatial sketchpad. This will, consequently, increase your likelihood to retain it rather than interfering with cognitive processing. Other similar activities, e.g. drawing mind maps (etc) of the material learnt while talking about it, will help strengthen and consolidate your memory.
Nevertheless, other factors may influence memory. Are you highly emotional, for example? Emotional events are remembered better, but these memories can be distorted. Perhaps practicing meditation, or utilising other means (e.g. writing) to lower neuroticism could elevate your memory. Meditation has also shown to create brain changes associated with enhanced memory
Are you also greatly influenced by language?
Loftus and Palmer (1974) also revealed that word choice contributes to a distortion of memory, i.e. reconstructive memory. To combat this interfering with recall, simply heightened awareness of the use of language in learning and interpreting information will make you aware of possible biases, and thus return to focusing entirely on impartial, accurate recall.
Are you also brought up with a skewed world-view? Bartlett’s schema theory reveals that your schema - i.e, the mental organization of information you know, affects memory recall. For example, for me, neuroscience is important - which is why I tend to better recall biology, chemistry, and psychology-related information and research. However, that’s simply my schema organizing my priorities and consequently, my thought processes. If your view on life and the world is impacting your memory, you may want to reconsider your goals in life and relate them to what you wish to recall.
Ultimately though, a large part is practice. The hippocampus (largely responsible for memory) undergoes neurogenesis (i.e, the growth of new neurons) throughout your life, so do take advantage of that. Attempt - force - yourself to recall what you wanted to earlier. Force those neural connections to form (via Long-Term Potentiation, if interested as to how).
I would also suggest watching your food intake. Considerable research has shown that processed carbohydrates, specifically gluten, disrupt brain health - through many mechanisms e.g. hindering cholesterol transport to the brain, advanced-glycation end product (AGEs) formation, inducing gluten sensitivity and inflammation, etc. Moreover, excessive fat consumption is also linked to poor memory. I would overall recommend you to thus reduce your carbohydrate intake (don’t curb it completely), eat a moderate amount of fats, and a higher amount of protein. Avoid sugars as much as you can - they are literally death. Here is a good and simple article discussing the benefits of the “Mediterranean diet” on memory - Boost your memory by eating right - Harvard Health