“Memory” as seen from the perspective of a cognitive psychologist
When I say, “I’m a memory researcher,” something about it sounds fishy. I worry people will think I study methods of smoothly extracting things like long forgotten childhood memories or making people instantly forget something they have just seen. What I actually investigate is the “mechanism” of memory itself.
Dividing memories into types and investigating the mechanism
There are different kinds of memories. In cognitive psychology, a field of study that is interested in how the mechanism of memory works, a telephone number you have temporarily memorized and the knowledge that if you dial 117 you will hear a recording of the current time are considered different kinds of memories. The former is referred to as “short term memory” and the latter as “long term memory.” This distinction is made because it is hypothesized that these types of memory have different mechanisms, or, in other words, have different mechanisms operating in the background. Taking short and long-term memory as an example, based on direct experience it may indeed seem that memorizing something temporarily and using knowledge you have permanently acquired are accomplished with different mechanisms. As I said, however, this is only a working hypothesis, and it cannot simply be assumed that these two kinds of memory have different mechanisms.
Even regarding the division between short and long-term memory, the debate began a long time ago and continues to rage today. Giving two different explanations of these two types of memory is still the standard approach in cognitive psychology textbooks (Atkinson & Shiffrin, 1968). On the other hand, however, there is also recent research that takes a negative view of this hypothesis and suggests it may be possible to explain them with a single mechanism (Russo & Grammatopoulou, 2003). There are solid arguments for both the view that the distinction between short and long-term memory is necessary and the view that it isn’t.
Change perspective? Change approach? Further divisions
If there is a longstanding debate that cannot be resolved, it is presumably important to reconsider how we approach the problem. It is obviously important to think about things from a new perspective or a different angle, and here there is also the method of making more detailed distinctions. This might also be described as “putting things in order.” There are different kinds of memory because someone distinguished between them, but that doesn’t necessarily mean that what hasn’t been distinguished is all the same. There are cases in which types of memory that should be considered separately remain mixed together.
What I realized through my research is that within temporary memory there is “item memory” and “order memory.” Imagine that words are displayed one after another on a screen, and you are to memorize both the words themselves and the order in which they appear. To repeat the words in the order you memorized them, you need to memorize both the words themselves (called the “item”) and their order. This is called a “serial recall task,” and is one of the tests with simplified conditions we use to make studying memory easier. What if we tried separating item memory and order memory? While the view that item memory and order memory have different mechanisms had been proposed in the past (Bjork & Healy, 1974; Toga & Hoshino, 2012; Toga, Moru, & Hoshino, 2010), it had never been introduced into the debate over whether it was necessary to distinguish between short-term and long-term memory.
After conducting several experiments, we obtained results that cannot be explained without hypothesizing, in regard to order memory, at least two mechanisms, one that relies on phoneme information that can only be used for a very short time and one that relies on some other kind of information not related to sound (Toga & Hoshino, 2015). It is not clear whether this is the case when it comes to item memory. As a result, for the time being at least, in the case of order memory it seems better to assume a functional distinction between short and long-term memory.
The mechanism of the memory is one part of the mechanism of the mind
Apart from dividing memory into types, it is also important to examine the possibility that types of memory that have been distinguished may in fact operate with the same mechanism in the background, and how these different types of memory are related to each other. And when it comes to these relationships we shouldn’t limit our investigation to memory. The leap forward in memory studies in recent years was made possible by moving from a concept of short-term memory as only storing information to a concept of “working memory” that emphasizes short-term memory’s connection to the cognitive information processing that engages in activities such as reasoning, language comprehension, and learning (Baddeley 2012; Baddeley & Hitch, 1974). In this memory project, too, we are focusing on the factors affecting this working memory. Memory is involved in various workings of the mind.
Understanding the mechanisms of memory, let alone the mechanisms of the mind, requires a lot of time and effort. Today’s scientific advances are startling. To avoid a future one hundred or two hundred years from now in which we understand everything but our own minds, I want to do whatever I can, however little that might be, to elucidate the mechanism of memory as one piece of this larger puzzle.
- Atkinson, R. C., & Shiffrin, R. M. (1968). Human memory: A proposed system and its control processes. In K. W. Spence, & J. T. Spence (Eds.), The psychology of learning and motivation: Advances in research and theory. Vol. 2. New York: Academic Press. pp. 89-195.
- Baddeley, A. D. (2012). Working memory: Theories, models, and controversies. Annual Review of Psychology, 63, 1-29.
- Baddeley, A. D., Hitch G. J. (1974). Working memory. In G. A. Bower (Ed.), The psychology of learning and motivation: Advances in research and theory Vol. 8. New York: Academic Press, pp. 47-89.
- Bjork, E. L., & Healy, A. F. (1974). Short-term order and item retention. Journal of Verbal Learning and Verbal Behavior, 13, 80-97.
- Russo, R., & Grammatopoulou, N. (2003). Word length and articulatory suppression affect short-term and long-term recall tasks. Memory & Cognition, 31, 728-737.
- Toga, M. & Hoshino, Y. (2012). Effects of word length on order memory in short-term retention: Examination of the item-order encoding trade-off. The Japanese Psychonomic Science, 31, 12-23.
- Toga, M. & Hoshino, Y. (2015). Word length effects in immediate and delayed order reconstruction tasks. The Japanese Journal of Cognitive Psychology, 12, 121-128.
- Toga, M., Moru, S., & Hoshino, Y. (2010). Effects of memory for phonological information on short-term memory for order in elderly and aged people. Ritsumeikan Journal of Human Sciences, 21, 57-66.