When asked about memory, many persons with ADD syndrome describe a peculiar contradiction. Many report that they are quite good at accessing long-term memories, for example, they can recall details from experiences years earlier. Yet most complain of chronic difficulties in their ability to hold one thought or bit of information in mind while simultaneously doing something else. They often forget what they were just about to say or the purpose for which they have just walked into a room. They tend to forget where they have most recently placed their keys, what they have done with a needed document, or whom they have just dialed on the telephone.
Chronic difficulties with memory appear to be a core problem in ADD syndrome, but the impairments are not generally with long-term storage memory; instead they involve "working memory," a term that has been used in many different ways, most of which are unrelated to the older term "short-term memory." Working memory has several functions. An important one is to hold one bit of information active while working with another. One patient described his impairment of this essential function as lacking a "hold" button in his memory.
I'm really good at remembering things from a long time ago. I can tell you the whole story line from movies I saw just once years ago and haven't seen since. But even though I'm the best in my family for remembering things from way back, I'm the worst at remembering what happened just a few minutes ago. If I call the Information operator to get a phone number, I can never remember it long enough to dial it. I always have to write it down or I'll mix up the numbers.
I'll go into a room to get something and then I'm standing there scratching my head and wondering what I came in there for. Or I'll go to the store to get five things I need to fix dinner. If I don't write them down I'll only be able to pick up one of them;
I can't remember the other four to save my life. It's like my mind is a multiline phone where the hold button doesn't work. If I am trying to remember one thing and then I set it aside even for just a minute to think about or do something else, I totally lose what I was trying to hold onto.
Working memory, then, is not short-term memory. It does not function as the queue on a computer's printer, simply holding information briefly while it awaits further processing. Working memory, instead, is like a very active computational unit that not only holds information, but also actively processes this current information in connection with the vast files of longer-term memory. In other words, working memory might be compared to the RAM of a computer combined with its file manager and search engine.
Working memory is essential for participation in a group discussion or in individual conversation where one has to try to understand what someone is saying while formulating a response. People with ADD syndrome often have a great deal of difficulty with these concurrent functions.
It's so frustrating when we're having class discussions. The teacher will ask a question and I'll have a good answer for it, so I'll raise my hand. And then she calls on somebody else first and I have to listen to this other kid say his answer. Then she comes back and asks me to say my answer. When she does that I just have to shrug and say, "I don't know." By then I've not only forgotten what I was going to answer; I've even forgotten the question.
When I'm just talking with friends, lots of times I just interrupt and say what I've got to say. I know that if I'm polite and wait until the other person has stopped talking, I won't ever be able to remember what I was going to say. The problem is that while I'm trying to keep in mind what I want to say, often I am not paying enough attention to what the other person is trying to say to me. Usually both my thought and theirs gets washed away from my mind.
This student clearly illustrates how impairments of working memory can interfere with both receptive and expressive aspects of communication between individuals and within groups. His complaint, common among persons with ADD syndrome, highlights the difficulty in maintaining reciprocal communication when working memory function is impaired.
Another aspect of working memory involves the retrieval of information from the files of longer-term memory. One student described how his impairments of working memory interfered with his taking tests.
It's so frustrating when I study hard for tests and then can't remember what I learned. I'll study hard and learn everything we're supposed to know. My friends quiz me and I've got it all down. Then, the next day I go in to take the test, figuring that I'm going to get a good grade. And then when I'm actually taking the test, a big chunk of what I knew so well the night before just evaporates. It's like I have a file in my computer and can't remember the file name to pop it up. I know the stuff is in there, but I just can't get to it, so I can't put it down on the test. Then a few hours after the test, something will jog my memory and it's all back again. It's not that I didn't have it in there. It was in my mind, I just couldn't retrieve it when I needed it.
The student's complaints about being unable to recall lessons studied and seemingly mastered the night before illustrate a distinct type of memory problem: defective retrieval of learned information. His comparison to forgetting the name of a computer file is apt. Persons with ADD syndrome often complain that they have chronic difficulty pulling up from the files of longer-term memory the information needed to do a task at hand. Sometimes the problem is recalling the name of someone whose face has just been recognized as familiar. Sometimes the problem lies in retrieving information or procedures needed to answer a question or solve a problem.
Many aspects of academic work depend heavily on the effective functioning of working memory. When reading, one needs to hold in mind the sounds symbolized by the first part of a word while decoding the sound of later syllables to recognize the word as a whole. One then has to retrieve from memory the meanings associated with that word and hold those in mind while linking them to meanings of other words to get the full meaning and context of the entire sentence. This process happens automatically for fluent readers as they rapidly link up and absorb layers of meaning built on words, sentences, paragraphs, chapters, and so on. Persons whose working memory is significantly impaired, however, may experience great difficulty in understanding an entire text, even if they are quite competent in decoding each word. Reading comprehension is built on the effective functioning of working memory in conjunction with an active, sustained attention to the text.
Working memory is also essential for doing math, even simple arithmetic. If one cannot keep in mind what quantities have been borrowed or need to be carried from one column to another in calculations, one's answers are not likely to be correct. And if one cannot keep in mind the sequence of operations, then much of algebra, geometry, and higher math becomes incomprehensible.
Written expression also places strong demands on working memory. One college student described how working memory problems interfered with her writing:
When I write sentences to answer exam questions or to write an essay or a term paper, I keep getting lost. I start out with one thing I am trying to say and then I get going on that one thing and forget about what I was supposed to hook it up with. Usually my answer doesn't really fit very well with the question.
It's even worse in longer writing projects like an essay or a term paper. There I'll make a point and then forget to explain it enough. Or I'll just wander off the path. Teachers are always writing in the margins, "Elaborate this more" or "How did you get from what you just said to this?" One teacher said that I keep forgetting where I am supposed to be going. She's right. When I have to write longer things it's like I'm just wandering around in what I write. I can't stick to the topic and then explain the different parts to get to wherever I'm supposed to take it.
To write a paragraph, letter, or essay, one has to consider simultaneously many elements: Who is the audience? What is the major point? How can I connect subordinate points to the main idea? Especially with longer or more complex writing tasks, it is necessary to hold several viewpoints in mind while putting words and images together understandably. This process presents a major challenge to working memory.
There has not been much research on students who have problems with written expression, but preliminary studies indicate that persons with ADHD demonstrate a disproportionately high incidence of impairment in this respect. For reasons explained in Chapters 4 and 8, it is likely that working memory impairments of ADD syndrome play a significant role in creating difficulties with written expression among ADHD students.
Working memory is involved not only in academic tasks, but also in countless aspects of everyday life, as one holds briefly in mind the continuing flow of perceptions of current external events—sounds just heard, images just observed, impressions just formed. Akira Miyake and Priti Shah (1999) describe how working memory plays a crucial role in moment-by-moment integration of memories held "internally" in long-term memory stores and those transient memories currently coming in from "external" sources:
During the performance of many (if not all) complex everyday cognitive tasks, the processing of external information and internal information needs to interact dynamically, going back and forth between information distributed across the internal mind and the external world. . . . Working memory . . . may serve as the important interface between external representations and internal representations. (p. 466)
Problems with integrating internal and external information can have a substantial influence on one's ability to link new information being acquired with other information already in mind. One illustration is a student who had great difficulty taking his SAT, a test required for college admission.
I took my SAT last week. I know I did really poorly because I wasn't able to finish a bunch of the reading comprehension questions. They give you this passage of three or four paragraphs to read and then you have to answer five multiple-choice questions about what you have just read. Most of them are really dense reading, with lots of details. And the questions are tricky, often hinging on very specific details in the text.
It took me so long on each question! I couldn't remember what I had just finished reading. I would read the passage and then for each question I needed to read it all over again to find the answer. I had to keep reading this same passage over and over again. I tried reading the questions first so I'd know what details to look for, but by the time I did that and then got back to the paragraphs, I had forgotten the questions. This kind of thing happens to me a lot.
Sometimes this need to reread is due to the "passive reading" problem described in the vignette earlier in this chapter. In other situations, it appears that the reader has actively engaged with the text, but is simply not able to hold its meaning in mind while reading subsequent parts or when addressing questions immediately following the reading.
The difference between problems of working memory and problems of insufficient attention has been a matter of debate among researchers. Neuroscientists studying memory functions have argued that what is currently referred to as working memory is not simply a memory unit of the mind, but a complex system that involves both "working attention" and "working memory" serving together to manage the continuous flow of information in the mind. Chronic impairments in this complex system are an important aspect of the ADD syndrome.
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