25 Memory

An enormous amount of information is processed by our senses every day. As described, when discussing observational learning, some of it is attended to and some of it is ignored. Some of it is remembered and some is forgotten. Memory and forgetting have been important topics in psychology since the start of the discipline. Hermann Ebbinghaus (1885) invented the 3-letter nonsense syllable (e.g., GUX, VEC, etc.) in order to eliminate the effects of prior familiarity. He generated the first learning and forgetting curve s for over 1,000 lists of nonsense syllables using himself as the subject. Whereas Ebbinghaus’ immediate recall was almost perfect, within nine hours retention dropped to less than 40 per cent. His performance continued to decline to about 25 per cent retention after six days and approximately 21 per cent after a month (see Figure 6.8).

Figure 6.8 Ebbinghaus’ forgetting curve.

Psychologists have tried to understand the mechanisms involved in memory and forgetting. An important question is whether forgetting is simply a function of the passage of time or the result of interference from other memories or activities. Since the time of Ebbinghaus, two significant sources of interference have been identified. Retroactive interference (i.e., working backwards) occurs when learning new materials reduces the ability to recall previously learned material. Proactive interference (i.e., working forwards) refers to the detrimental effect of previously learned material on the memory of new material (Slamecka & Ceraso, 1960). For example, if a student learned Spanish in high school and French in college, sometimes the new French vocabulary might interfere with remembering the former Spanish vocabulary. This is retroactive interference. If the prior learning of Spanish interfered with recalling the more recently learned French, this would be considered proactive interference. In the case of Ebbinghaus, as he learned more and more lists, he was increasing the buildup of both retroactive and proactive interference. That is, if he learned new lists before being asked to recall a previously learned list, this would result in retroactive interference. Proactive interference would occur when prior learning impeded learning a new list.

Starting in the late 1950s, researchers started distinguishing between different types (or stages) of memory. Sensory memory (sometimes referred to as very short-term memory) is basically a very brief continuation of sensation. Sensory memory exists immediately after presentation of a stimulus, is unconscious, and highly detailed (Sperling, 1960). Depending upon the variables previously considered under observational learning, some of the details will be attended to and others ignored. The attended to details may enter consciousness for further processing in the form of different rehearsal strategies. This longer-lasting, but still temporary stage, is usually referred to as working or short-term memory (Brown, 1958; Peterson and Peterson, 1959). Sometimes adapting to one’s environment only requires the use of currently available knowledge (e.g., after looking up a phone number). At other times, one may adapt by taking advantage of prior direct and indirect learning (e.g., when calling a family member or friend). Long-term memory refers to this much longer-lasting (perhaps permanent) stage.

Computers became information-processing models for human memory with sensory, short-term, and long-term memory linked in sequential stages. Atkinson and Shiffrin (1968, 1971) proposed the three-stage model of memory portrayed in Figure 6.9. Input (i.e., environmental sensory information) available in sensory memory had to be attended to in order to be available for rehearsal in short-term memory. There, the information had to be continually rehearsed in order to remain available. Then it needed to be elaborated upon and encoded in a manner which could be interpreted, stored, and retrieved at a later time from the more permanent long-term memory. As shown in Figure 6.4, information from long-term memory can be retrieved into short-term memory to address immediate adaptive needs. We will now elaborate on the methods and findings of the classic experiments which led to the Atkinson-Shiffrin information-processing model of human memory.

Figure 6.9 The Atkinson and Shiffrin Model of Memory.

Sensory Memory

George Sperling (1960) developed an ingenious procedure demonstrating that a great deal of information may be retrieved from a stimulus for a brief period of time after it is removed (1/20th of a second in Figure 6.10). If you show a person a matrix of twelve letters and ask them to recite as many of the letters as they can soon afterward (up to a second in the Figure), they usually are able to retrieve between four and five of the items.

Figure 6.10  Sperling’s partial-report procedure.

Sperling believed that the act of reporting what they remembered interfered with maintenance of the information, resulting in an inaccurate estimate of the actual amount retained. He developed a partial-recall procedure in which a high-, middle-, or low-frequency tone indicated which row of the array should be reported on an individual trial. It was demonstrated that up to about a quarter of a second, individuals were able to report twice as many of the items as with the full report method.  In order for this to occur, the full array had to be available for processing. Visual sensory memory is often referred to as iconic memory. It has been determined that auditory sensory memory, often referred to as echoic memory, is more durable than visual information and can last several seconds (Cowan, Lichty, & Grove, 1990). This makes it possible to understand spoken sentences. Still, the limitations of auditory memory impact upon the ability to retain lecture material. A lecture requires processing the information contained in several sentences extending over lengthier time intervals.

Short-Term Memory

The information remaining in sensory memory is available for further processing through the conscious act of rehearsal. We have all had the experience of having to look up a phone number again if we are distracted before dialing. An important question raised by Brown (1958) and by Peterson and Peterson (1959) was how long information would remain consciously available in the absence of rehearsal. In order to determine this, it was necessary to ask people to recall information after different time intervals without rehearsing the material. This was accomplished by having them count backwards by three. You can try this yourself if you don’t think it would work. Look up a phone number and start counting backward from 1,000. See how long you can go before having to go back and look it up again. It was found that when rehearsal was prevented, retention of trigrams (i.e., three consonants) declined from 80 per cent after three seconds to 10 percent after 18 seconds. Thus, it is not surprising that if you are distracted soon after looking up a phone number, you will need to look it up again.

Keppel and Underwood (1962) reviewed Peterson’s and Peterson’s results and noted that memory was very good at all the intervals on the first few trials. Performance deteriorated, however, with additional trials. This raised the question of whether the decline in short-term memory as a function of interval length resulted from delay or proactive interference from prior trials. Waugh and Norman (1965) tested this by giving subjects lists of 16 numbers. After the last item, the subject was asked to report the number which appeared immediately after one of the numbers in the list. Digits were presented every second or every four seconds. By varying both the time interval and whether the target number appeared early or late in the list, it was possible to determine which variable was more important. If the time interval were more important, the position of the item in the list should not matter. If the number of items prior to the target was more important, the time interval should not matter. It turned out that the number of prior items had a much greater effect than the delay. Short-term memory loss is primarily the result of interference when someone is not actively rehearsing the material.

In addition to knowing the duration of short-term memory, it is important to know its capacity. That is, how much information can you maintain in consciousness if you are allowed to rehearse? Memory span tests are one way of addressing this question (Humpstone, 1917). You can be asked to repeat letters, words, or numerical digits in order. Items are added until you are correct on less than 50 per cent of the test trials. One of the most cited articles in the psychology literature is “ The magical number seven, plus or minus two: Some limits on our capacity for processing information” by George Miller (1956). Miller examined the data from different types of short-term memory tasks, including memory span. He came to the conclusion that there is a relatively small amount of information we can retain in consciousness. He suggested that we are limited to between five and nine chunks of information. A chunk is similar to what we previously referred to as a gestalt; a meaningful unit. For example, study the following list of letters for about fifteen seconds and then look away and see how many you can correctly repeat:

mbicbnifbacbiac

Probably you were only able to correctly repeat about seven letters.

Now do the same with the same letters organized as follows:

ibmnbcfbiabccia

Now you may be able to repeat the entire list since they can be grouped into five chunks of three.  Telephone companies try to help us out with our short-term memory limitations by grouping the numbers. Probably you have used mnemonics (i.e., memory enhancing techniques) to memorize different types of information. For example, the word HOMES might help you remember the five great lakes (Huron, Ontario, Michigan, Erie, Superior). Roy G Biv might help you recall the sequence of colors comprising the visual spectrum (red, orange yellow, green blue, indigo, violet). In the following chapter, we will review cognitive processes, including concept formation.

Long-Term Memory

Think of all the concepts you learned as children; the ABCs, numbers, names of relatives, types of food, names of feelings, etc. Think of all the skills you acquired; walking, talking, getting dressed and tying your shoes, riding a bike, etc. Think of different events in your life; birthday parties, fun with your siblings and friends, teachers in different grades, ball games and dances, graduations, etc. Think of how you feel when reading about a calm summer day, watching a close sporting contest, or hearing a buzzing bee. These are all examples of different types of long-term memory included in the overview provided in Figure 6.11 (Squire, 1986, 1993).

Figure 6.11 Types of long-term memory (adapted from Squire, 1986, 1993).

The first distinction in types of long-term memory relates to whether conscious effort is required for recall to occur. Explicit (declarative) memory requires conscious effort whereas implicit (non-declarative) memory does not. For example, recalling the name of a type of food you haven’t eaten for several years or when you met your best friend requires conscious effort. No effort is required to recall how to ride a bike or to feel relaxed when reading about a calm summer day.

Explicit memory can be sub-divided into sematic memory and episodic memory (Tulving, 1972). Semantic memory consists of your entire knowledge base including your vocabulary, concepts, and ideas. Episodic memory consists of your chronological listing of life events. A food type is an example of semantic memory. When you met your best friend is an example of episodic memory.

Implicit memory can be sub-divided into procedural memory and emotional memory. Procedural memory refers to all the motor skills you are able to execute. Emotional memory refers to the feelings experienced based on prior experience. Bike riding is an example of procedural memory whereas a fear of buzzing bees is an example of emotional memory.

We will now consider the factors influencing how these different types of information become stored in long-term memory. This has practical applications as you attempt to achieve your potential. Improving your long-term memory will help you adapt to many of the demands of your physical and social environment. It will help you learn your course material, not only to perform well on exams, but also to best apply the knowledge, skills, and attitudes you acquire to your future educational and career objectives.

Figure 6.9 indicates that maintenance rehearsal strategies, consisting of repeating information over and over again, are sufficient to retain information in short-term memory. More active elaborative rehearsal strategies related to the meaning of material, however, are far more effective for transferring information to long-term memory. Elaboration can be in the form of relating new information to previously acquired knowledge or to one’s personal experience. When studying for exams, rather than simply trying to memorize information through repetition, it is more effective to try to describe the information using your own words. You can try to apply the information by making up your own examples or describe how the information relates to other things you know. As described in Chapter 1, an extremely effective study strategy is to make up questions and then test yourself. The finding that this strategy improves recall and test results in college students (Roediger & Karpicke, 2006; Einstein, Mullet, & Harrison, 2012) and the elderly (Meyer & Logan, 2013) has been labeled the testing effect. Another effective way of determining if you understand information is to try to teach it to someone else. This is only possible when you have a thorough understanding of the material yourself.

One of the most important variables influencing your ability to learn, remember, and apply information is how it is organized. Effective lecturers and textbook writers attempt to use schemas (Rumelhart, 1980) and scripts (Mandler, 1984) in order to achieve their instructional objectives. Schemas organize information in a coherent way while scripts create a meaningful sequence. In the previous chapter, I described two schemas developed by Skinner to organize behavioral contingencies and intermittent schedules of reinforcement. Psychology studies how nature and nurture interact to influence the potential for human thought, feeling, and behavior. This description determined the schema for organizing the book. I hope this helps you see where each of the content areas (i.e., chapters) fit within the context of the entire discipline of psychology (see Figure 6.12).

Figure 6.12 Nature/nurture schema for organizing the textbook chapters.

I once read a review suggesting that starting a biological psychology textbook with a description of a neuron was like starting a book about airplanes with a description of a screw. When possible, it is helpful to create an overarching organizational schema (i.e., an “airplane”, “big picture” or “forest”) portraying the relationships between the different components (i.e., parts, little pictures, or trees). The nature/nurture schema for human potential was an attempt to create such an overview of the different content areas of psychology. Your potential is initially determined by your unique (assuming you are not an identical twin) genetically determined physical and biological characteristics, sensory capabilities, needs, and drives (i.e., “nature”). Ultimately, the direct and indirect learning experiences to which you are exposed (i.e., “nurture”) will impact upon your personality development and the extent to which you achieve your individual potential (“nature/nurture”).

Maslow’s human needs pyramid is a hierarchically organized script prioritizing categories of human needs. According to Maslow, one first needs to satisfy basic survival needs before being able to concentrate on interpersonal relationships, and so on. Atkinson and Schifrin’s three-stage memory model is another example of a script. Information sequentially flows from sensory, to short-term, to long-term memory. Another script, mentioned below as well as in Chapter 7, is the sequential development of technologies resulting from application of the scientific method. Such technological growth is rapidly transforming the human condition. Kurzweil (2001) attributed the accelerating pace of technological achievements to the recording of prior successes. Without this recording, individuals and cultures would not be able to profit from prior advances.

Preparing for School and the 3 “R”s

It is through indirect learning that the benefits of direct learning, including tool-making and technological change, are recorded and disseminated among humans. This is as true for the Nukak as it is for us. The Nukak use observational learning and language to socialize children and teach survival skills. Whereas the Nukak’s and our basic survival needs are the same, technologies have changed our physical conditions, population densities, and adaptive needs. The Nukak spend their time each day meeting their basic survival needs as individuals and a species.

Last chapter, we saw how verbal behavior can be understood through the application of basic learning principles. Once children speak, it is possible to use language to expand their knowledge and skills. Rather than acquiring hunting, gathering, and other survival skills, you have probably been acquiring school-related knowledge and skills since you were old enough to speak and prepare to attend school.

Children enjoy listening to rhymes. Children enjoy singing. Children REALLY enjoy singing rhymes! It is not unusual for adults to start singing the alphabet song to children as young as 2 years of age. The alphabet is an example of a serial list in which items always appear in a particular order. Serial learning was one of the first types of memory studied by Ebbinghaus. The serial-position effect (Hovland, 1938) refers to the finding that one learns the items at the beginnings and ends of lists before learning the items in the middle. The alphabet song divides the 26 letters into 4 manageable chunks based on rhyming sounds. This makes learning the entire sequence fun and relatively easy, even for a very young child. Once this is accomplished it is possible to match the sounds to their written forms, an important precursor to learning to read.

Counting represents another fundamental serial learning task for children. It is different from the alphabet in that the sequence of items is not arbitrary. That is, there is no reason “a” has to be the first letter of the alphabet and precede “b”, etc. However, “1” has to be first, and “2”, second, etc. Counting, therefore, requires additional learning in which the numbers are spoken in the presence of the appropriate quantities of different objects. Eventually, the child “abstracts out” the dimension of quantity and the different values. Similar to letters, the sounds are eventually associated with their written forms, an important precursor to learning arithmetic.

Implementation of compulsory education around the turn of the 20th century was an enabling factor for subsequent scientific and technological advances. In order for individuals and for a society to receive the full benefits of compulsory education, it is necessary that children be prepared for the first years of schooling. The richness of their experiences and extensive vocabularies provides many children with the basic knowledge and skills required to excel in pre-school and beyond. Unfortunately, as revealed in Hart and Risley’s (1995) findings, not all children currently receive the level of preparation necessary to immediately acquire the ability to read, write, and perform quantitative operations. Hopefully, parent education and pre-school programs such as Head Start, will reduce the continuing achievement gap between different segments of our population.

The phonetic alphabet, the basis for reading, has served as the major means of recording human knowledge since the time of the Phoenicians. There is certainly much truth to the statement that “reading is fundamental.” Learning to read is an excellent example of the importance of the Gestalt perspective. Reading may be broken down into a sequence of steps establishing larger and larger meaningful units (i.e., gestalts). Eye-movement recordings reveal that individual letters are not initially perceived as units. With increased experience, we are able to integrate the components into a relatively small number of distinct letters, followed by integration of letters into words. Mentioned previously, we perceive the letters of words simultaneously (i.e., as a “gestalt”), not sequentially (Adelman, Marquis, and Sabatos-DeVito, 2010). Eventually, we are able to read aloud fluently by scanning phrases and sentences (Rayner, 1998).

Learning to write requires establishing larger and larger behavioral units through shaping and chaining. As soon as a child is able to grasp a pencil or pen, parents often encourage her/him to “draw.” Once a certain level of proficiency is achieved, it is possible to teach the writing of letters and numbers. This may begin by having the child trace the appropriate signs and then fading them out so that eventually the appropriate symbol can be formed without visual assistance. Eventually fluency of writing letters, followed by words, followed by phrases and complete sentences is achieved. As children advance through the grades, they are assigned tasks requiring more extensive reading and writing.

Learning basic arithmetic is an extension of counting. It is possible to visually differentiate between small numbers of items (e.g., to tell the difference between 3 and 4). This is not possible once a threshold is passed (e.g., trying to see the difference between 10 and 11 items, or 20 and 21, or 120 and 121). It is necessary to accurately apply verbal counting to the actual number of objects in order to perform such tasks. Once a child is able to count objects, it is possible to begin teaching basic mathematics including: addition and subtraction; the base-10 system; multiplication and division; fractions, etc. For an early comprehensive treatment of the application of predictive and control learning principles to reading, writing, and arithmetic, I recommend Staat’s excellent book, Learning, Language, and Cognition (1968). One cannot overstate the fundamental importance of compulsory education to societal development and economic progress. Rindermann and Thompson (2011) conducted sophisticated statistical analyses demonstrating the powerful relationship of cognitive ability, particularly in the STEM fields (science, technology, engineering, and math), to wealth in 90 countries. The top 5% in cognitive ability contribute significantly, often in the form of scientific and technological advances.

Attributions

Figure 6.8 “Ebbinghaus forgetting curve” by Educ320 is licensed under CC BY-SA 4.0

Figure 6.9 “Atkinson-Shiffrin memory model” is in the Public Domain

Figure 6.10 “Sperling’s partial report procedure” by Psyc3330 w11 is licensed under CC BY-SA 3.0

Figure 6.11 “Types of memory” by SFWalker is licensed under CC BY-SA 4.0