Memory, according to Locke, is an act of the mind in which the agent, either by willing of the mind or by “turbulent and tempestuous passions”, revives a previously imprinted perception or idea with the knowledge that the perception or idea has been imprinted before. Although Locke made some very accurate claims about the mechanics of memory that have a basis in modern cognitive neuroscience, his theory is incomplete - it fails to address and develop a systematic and plausible explanation for the storage of impressions and consequent recollections of perceptions. In this essay, I will aim to develop a thorough interpretation of Locke’s theory of memory and consequently critique and offer a solution to the ambiguities mentioned previously, which will be grounded in a more modern understanding of memory.
Let’s start with the question: What exactly is memory to John Locke? According to Locke, the memory is “…the power to revive again in our minds those ideas, which after imprinting have thus disappeared, or have been as if it were laid out of sight…” This definition can be broken down into its individual components based off of some of Locke’s previous definitions. An idea to Locke is the object of our thinking, which originates in one of two ways – either by external, sensible objects, or through reflection. Locke has mentioned what imprinting means before - “…imprinting, if it signify anything, being nothing else but the making certain truths to be perceived.” We can now redefine Locke’s definition of memory to be the following: Memory is the power to revive again in our minds the objects of our thinking which are no longer in our conscious thoughts after certain truths about the objects have been perceived by the mind. Locke then goes on to describe memory as not only a power of the mind, but metaphorically, or perhaps literally1, suggests it is an actual object itself.
“This is memory,” Locke states, “which is as it were the storehouse of our ideas.” Locke then describes the process as “…laying up of our ideas in the repository of our memory.” Here, we have Locke seemingly describing memory as physical space in our brain which is capable of storing past perceptions or ideas. What is concerning is not the fact that Locke does not give an explanation as to why the memory is said to be a storehouse or repository of ideas, but the fact that Locke later states, “And it is in this sense, that our ideas are said to be in our memories, when indeed, they are actually nowhere, but only there is an ability in the mind, when it will, to revive them again…” This is contradictory information – Locke states that the memory is a storehouse of our ideas and then states that memories are actually nowhere. Perhaps Locke was making an analogy of memories being a repository of ideas, but even if this is true, it simply does not make sense that memories could be found nowhere in the mind. If this is the case, where do memories come from? If memories are not stored somewhere, then memories cannot exist in the scientifically accepted sense of the word. Before discussing how this ambiguous picture of memories might be amended, it would be helpful to develop a more complete picture of how the memory works in Locke’s view.
How do we actually gain access to a memory in our so called “storehouse” of ideas? When developing his theory of memory, Locke seems to have come across three primary ways we can revive ideas that have been imprinted in our minds before. The first of these is a willing of the mind, or rather, an active recollection of a memory for a certain purpose. Locke states, “…but only there is an ability in the mind, when it will, to revive [ideas] again.” He goes on to say, “… the mind is oftentimes more than barely passive, the appearance of those dormant pictures, sometimes depending on the will.” It seems that this method of reviving ideas does not depend on any external object prompting the spontaneous recollection of a past perception. For example, this does not depend on seeing a picture of a certain person and then recalling the memories you have shared with them. This seems to be something more along the lines of wanting to recall something – for example, you are trying to remember a formula that a friend forgot. You actively search within the “storehouse” of your ideas to bring the idea again into your consciousness. One could indeed argue that this specific example does require some sort of external prompting, and it does in a sense – everything must be traced back to a cause. However, in this example, the external prompting was not perceiving the formula in the external world and subsequently recalling that the idea of this formula is lodged somewhere in your storehouse of ideas - the external prompting was a cause in the external world to will the mind to recall the formula of its own accord.
The second way of reviving ideas that have been imprinted in our minds before, according to Locke, is the perceiving of external sensory information that seems to have a direct correspondence with the perceptions we have had before. Locke states the following when talking about ideas that lodge themselves best in the memory: “…that those that are oftenest refreshed by a frequent return of the objects or actions that produce them, fix themselves best in the memory…” Although Locke was certainly right about the reinforcement of ideas lodging themselves better in the mind2, what are the objects or actions that produce them? Is Locke talking about physical qualities? He goes on to say, “…and therefore those, which are the original qualities of bodies…these, I say, and the like ideas, are seldom quite lost, whilst the mind retains any ideas at all.” It is clear that what Locke is trying to say in this writing is that ideas in our mind which are revived the most can scarcely be lost into oblivion – a place in which memories are forever lost, and practically speaking, is the failure to revive a memory, according to Locke. However, by this same token, I would also argue that Locke is recognizing a way in which the mind can revive ideas. When we experience the physical qualities of bodies again - in other words, when we see a building that we have seen before - we are not actively willing our minds to remember the ideas concerning this physical object we have seen before. It is more of an unconscious process – we simply know that we have perceived this building before, and the conception of the building in our memory is strengthened for future recollection of the will or other methods of reviving memories. To summarize this second way of revival, it is a method that is triggered by the imprinting of ideas in our mind which have been imprinted there before (i.e. perceiving similar/same external sensory information), which causes a spontaneous revival of the previous result of imprinting that perception with the knowledge that the perception has been imprinted there before.
Lastly, Locke formulates a third and somewhat equivocal way that the mind revives ideas – a method that sounds extremely familiar to what would today be called “day-dreaming,” or even “mulling over an idea.” Locke says, “The mind very often sets itself on working in search of some hidden idea, and turns, as it were, the eye of the soul upon it; though sometimes too they start up in our minds of their own accord, and offer themselves to the understanding; and very often are roused and tumbled out of their dark cells, into open daylight, by some turbulent and tempestuous passion.” The first part of this statement is akin to actively willing memories, but the second part appears to be more of a random revival of certain memories. It is unclear what Lock means by “turbulent and tempestuous passion.” Perhaps he means a personal interest or emotion that could spark a revival of lost memories in our mind. For example, maybe I develop a sudden interest in Art, and remember that one of my old friends is now an Art professor. Maybe he is even referring to something external when talking about this, and hence, it would fall into the category of what I call Locke’s second method for reviving memories and there would not be a third way at all, but I am certain that what Locke is referring to here is something that it out of our active control, or “will,” since Locke states “…they start up in our minds of their own accord.” I would argue that whatever Locke means by “turbulent and tempestuous passions” is unnecessary for the revival of certain memories. In fact, I would say that simply sitting in a dark room, with all of your senses dulled and you not experiencing any particular emotion would cause a sudden revival of memories, or your mind to revive ideas of its own “accord.” Whether we know why or not, certain thoughts and memories simply appear in our streams of consciousness and then disappear without any particular reason3.
So far, we have a definition of what memory is according to Locke, an unclear picture of how memory is stored, and processes by which memories are revived from our “storehouse of ideas.” With this, we can develop a practical example to see the implementation of Locke’s ideas, and we will quickly see that it breaks down without a reasonable account of where memories are stored, or how they are stored.
You awake in the morning after sleeping through your alarm twice, dazed and confused after the excessive consumption of caffeine the previous day has negatively impacted your REM cycle. After getting ready and consuming your usual psychoactive drug in the form of coffee, your keys are not where they typically are. You panic, trying to remember where you could have possibly put them. This is what Locke referred to as “oblivion,” where memories are seemingly lost and we become ignorant. Using the second method of reviving a memory that I have previously described, you “will” as hard as you can to try to remember. The memory is not there. You relax and try to clear your mind, recounting the precise actions you made when arriving home yesterday. Seemingly out of nowhere, a memory injects itself into your stream of consciousness, or rather, your mind acts of its own “accord,” as Locke might have put it. You remembered you put it on the desk of your room last night. Where did this memory come from?
Locke says our memories are nowhere, but this is absurd. From this example, we can see that memories not only must exist somewhere, but that they have to be stored in a certain way. If they are not stored in a special, intertwined format, how is it that the linear recollection of related memories leading up to putting your keys on your desk suddenly injected a memory into your consciousness of where you put them? Furthermore, while recollecting what you remembered, you also recollected that you have had these perceptions imprinted into your mind before. If not, how did they get there? Lastly, it is important to note that Locke stated we have an “additional perception annexed to [memories].” If the original perceptions do not exist anywhere, then that must also mean these perceptions do not exist anywhere either, but this is simply incorrect. A framework can be developed which will explain not only the storage of memories, but how they are stored such that they can be linked to one another and revived through one of Locke’s methods.
Neurological work of Lashley and Penfield showed that the groups of neurons in our brains corresponding to long term memories are distributed throughout the cortex4. It is in this sense that memories can be thought of as actual physical substance. “Imprinting,” of ideas in our mind, as Locke said, is actually a process where perceptions are stored in groups of neuronal patterns in our brain which are primed to fire together during memory “revival.” With this knowledge in mind, it is clear that memories do indeed exist in a physical space, and this space is not really a “repository” or “storehouse,” but more like a scattered network. This clears up the problem that Locke had of explaining the storage location of memories inside of our minds. However, we still have a problem that needs to be addressed – how the process of retrieval actually works. I will show this through a system of symbolic representation, which can be applied to the context of the methods that Locke identified for the mechanisms of memory revival.
Assume that our memories exist in an associative web-like format, which according to modern neuroscience research, may not be far from the truth5. A single memory can be represented by M, which can correspond to either a basic perception of the way something looked, or perhaps a more complex theory (this part is not relevant at the moment). As Locke stated, we have an additional perception annexed to a memory, which we can describe as b, such that a memory that we know we have had before (i.e. has been encoded in our brains), can be represented as . There exist links between these memories that we can call C. These can be thought of as not only associations between memories, but paths that can be traveled along to retrieve a memory that might not be as strong as another memory in our brains, but is nonetheless associated with the stronger memory. Locke said that the more we revive certain memories, the stronger they become, and this is indeed true. So we can add an additional property to M, which is the strength of the memory (how vivid the memory is, how easily it can be retrieved on a scale from 1-100). So now we have some , which means: A memory that has been stored before and has a relative strength of 75%. With Locke’s definition of memory, knowledge that memories actually occupy physical space in the brain, and this system of how memories are stored in the brain, we can revisit the previous practical example and see that the process of memory revival becomes much more convincing.
You awake in the morning etc. Realizing your keys are lost, you start trying to recount what you do remember in an effort to find your missing keys. These memories are strong, and we will call them , , and , and let’s say that they consecutively correspond to the following three memories, which are linked together: you walk into your house, you get a drink of water, and then you rush upstairs to your room to check your email. You weren’t paying attention to where you put your keys down because you were too focused on your email, and thus, this memory (let’s call it ) is not very strong. However, they are linked to the previously mentioned chain of memories, and what you are trying to do when willing your mind to actively “revive” the memory of where your keys are is revive the memories that are stronger, starting from the beginning, and then following this chain of memories which are associated with the ultimate location of your keys. When the sudden recollection is injected into your consciousness, you have followed the chain and arrived at your goal, recovering a weak memory. It is also easy to see how this framework can help describe the process of the random revival of past perceptions in the mind, due to the nature of the web-like format in which memories are said to be stored. Thus, integrating this system into Locke’s theory of memory starts to make it more plausible, as the mechanics of recollection can be sensibly described and we are not left in confusion over the “revival” of memories from a “storehouse of ideas” that apparently does not exist.
Locke got a few things right in regards to memory, but he left many critical components out. Through this interpretation and subsequent critique and amendment to Locke’s theory of memory, I hope that I have created a more solidified foundation of memory which builds upon the foundation that Locke laid out.
1 Locke refers to memory as both a repository and storehouse of ideas, but does not elaborate on this any further, so it is unclear whether he meant it literally or as a metaphor
2 See http://www.nature.com/nrn/journal/v8/n4/abs/nrn2090.html for more info
3 In his essay, Free Will, Sam Harris argues that thoughts are often times random events in our stream of consciousness that sometimes have no particular cause or “willing,” and that we cannot know why this is exactly.
4 See http://www.human-memory.net/processes_storage.html for more info
5 See https://www.sciencedaily.com/releases/2016/11/161115121524.htm for more info