Human Memory

Early Memory Studies Ebbinghaus Hermann Ebbinghaus began his work in 1885 using himself as his only subject. He used CVC nonsense trigrams (e.g., DAX, BIV) for memory materials and identified several basic memory principles which have stood the test of time: Forgetting function -- material is forgotten rapidly, then decreases more slowly over time (i.e., a negatively accelerated curve): Delay (days) minutes 1 hour 9 hours Percent Savings

Early Memory Studies (con ’ t) Overlearning -- additional rehearsal after reaching criterion increases savings after a delay compared with the savings without the additional rehearsal. Savings -- given material which has been forgotten to some degree after a delay, it takes less time to relearn the material a second time.

Input Stage Model of Memory The 1960 ’ s and 70 ’ s saw the development of a “ Stage ” model of memory. Separate stores, or stages, were proposed which handled different stages in the processing of memory from input into permanent storage. Retrieval Rehearsal Transfer Attention Short-term Memory Sensory Memory Long-term Memory Decay Displaced Forgotten?

Serial Position Effect This model suggests there are two different main memory systems: the STM and LTM. The “ serial position effect ” provides considerable evidence to support that idea. The enhanced recall of early items is called the “ primacy effect ” and the enhanced recall of later items is called the “ recency effect. ”

Serial Position Effect (con ’ t) When subjects are asked to count backward before recall, the recency effect disappears. When the word list is presented slower, pre-recency recall is improved, but not recent terms. Additional support is provided when variables are manipulated to affect the STM and LTM independently.

Capacity of Working Memory This model implies there are static “ slots ” into which the information is placed. The STM is, however, a dynamic environment. More dynamic methods of measuring capacity have been developed to measure the STM ’ s capacity to do things when working, not passively holding items for immediate recall. Just how big is working memory? A common test for measuring the capacity of working memory is “ digit span. ” The typical person can recall 7± 2 items. Individuals with larger working-memory capacities tend to be better at verbal tasks, reasoning tasks, and less likely to be distracted and more able to “ keep on task. ”

The Central Executive Visuospatial buffer - temporary storage of spatial information that will be needed in the near future. Articulatory rehearsal loop - temporary storage for verbal material. Most importantly, the “central executive” - a collection of cognitive resources needed to organize and control our thoughts and actions. Today, psychologists do not believe there is a single STM structure as suggested in the stage model, but actually working memory consists of several components:

The Central Executive (cont’) One area believed to be crucial for the functioning of the central executive is the prefrontal cortex (PFC). Damage to this area may result in difficulties with inhibiting habitual responses. For example: goal neglect – relying on habitual responses even though they do not move one toward their goal perseveration – produce same response over and over even though the task changes and requires a different response Additional evidence comes from studies involving chimps. In a typical delayed match-to-sample task, the monkey ’ s area 46 (a prefrontal area) is active only during the delay, perhaps “ holding ” the information until the curtain is removed. Damage to the PFC also reduces one ’ s ability to organize or plan.

From STM Into LTM How does working memory get information into the LTM? “ Rehearsal ” is the means by which information is transferred into LTM. There are, however, two types of rehearsal: maintenance rehearsal and elaborative rehearsal. “ Maintenance rehearsal ” is simply thinking about items over and over in a mechanical way with little attention to or concern for meaning. “ Elaborative rehearsal ” involves thinking about the meaning of the to-be-remembered material and relating it to things you already know.

Depth-of-Processing If repetition does not result in transfer to LTM, what does? Clearly, seeing something over and over is insufficient for getting something into LTM. Unless some “ effort ” is given to the material, it is unlikely the information will make it into LTM. The idea of “ depth-of-processing ” suggests that the manner in which material is rehearsed (i.e., deeply and meaningfully) is most critical, not the amount of rehearsal.

Isn’t “Desire” More Important? It seems reasonable to believe that if one truly wants to remember something, just repeating it over and over could work. What role, then, does one ’ s intentions to learn affect getting information into LTM? Whether one “ intends ” to learn or not, it is what happens at the time of learning that makes the difference. So long as effective rehearsal strategies are used, it doesn ’ t matter whether there is an intention to learn or not.

Memory Connections While our intentions are of little importance, it is clear that how we first interact with the material at the time of learning is crucial for subsequent recall. How does deep processing at time of learning lead to improved recall? Simply, it provides better or more connections to the to- be-remembered material. Connections provide numerous retrieval paths by which you can access or retrieve the to-be-remembered information. Elaborative rehearsal – embellishing with additional, relevant information – is an effective rehearsal strategy for increasing connections.

Elaborative Rehearsal For example... Suppose you were trying to learn how an action potential occurs. You might imagine a department store (the axon) about to open for a big sale. Inside are a number of employees with somewhat “ negative ” attitudes (negatively charged ions) regarding the madness that is about to occur. Outside the store are many people with “ positive ” attitudes regarding the good deals they may find inside (positively charged ions), so they are anxious to get in. The excitement builds (excitatory stimulation) until the crowd can ’ t stand it any longer (threshold is reached), when suddenly the doors open and the customers come rushing in (depolarization) and then the action is non-stop (the action potential). The extra thought and additional embellishments provide a greater number of potential connections to the material.

Elaborative Rehearsal (con’t) Additionally, you process material more deeply when: you come up with your own examples explain the material to another person just talk and think about the material. All of those activities can establish new connections.

Organization And Memory Identifying the organization or order of to-be-remembered material is an excellent way to establish connections. If no organization is present, you can impose your own organization on material. That is the basis of “ mnemonics. ” Some standard mnemonics include: First-letter association Visual imagery Method of Loci Peg Word There is, however, a downside to using mnemonics … they tend to limit the number of connections to the material you want to remember and what you know (e.g., the “ peg ” word).

Multiple Connections By focusing the link, you may be missing the opportunity to understand the material and establish many more useful connections that might lead to better retrieval. Multiple connections serve two purposes: facilitates understanding of the to-be-remembered material, providing better learning multiple connections provide more retrieval paths during recall. “ Understanding, ” then, is the best means by which we can form connections.

What You Know Matters Where do you make all these connections? Simply put... to other (relevant) memories or knowledge. An individual with a wealth of relevant knowledge will, when presented with new material, have a ready structure or framework onto which connections can be made. In short, the more you already know, the easier it is to remember more. In short, the more you already know, the easier it is to remember more.

A Technique To Help PQ4R Method - useful technique for reading textbooks: Preview - read each subheading in the chapter Questions - develop questions based on each subheading Read - try to answer questions for each section while you read Reflect - think about the text as you read it and try to understand it, come up with your own examples, and try to related the material to your prior knowledge and personal experience Recite - try to recall the material and the answers to your questions when you finish reading a section. If you cannot, reread the portions with which you had trouble. Review - once you have finished reading the entire chapter, try to recall the main points and the answers to your questions.