Psychological Science – Chapter 7: Memory 7.1 Memory Systems • Memory is a collection of several systems that store information in different forms for differing amounts of time. • The Atkinson-Shiffrin Model o Memory is a multistage process. Information flows through a brief sensory memory store into short-term memory, where rehearsal encodes it to long-term memory for permanent storage. Memories are retrieved from long-term memory and brought into short-term storage for further processing. o The Atkinson-Shiffrin model includes three memory stores: sensory memory, short-term memory (STM), and long- term memory (LTM). o Stores retain information in memory without using it for any specific purpose. o Control processes shift information from one memory store to another. o Some information in STM goes through encoding, the process of storing information in the LTM system. o Retrieval brings information from LTM back into STM. This happens when you become aware of existing memories, such as what you did last week. • Sensory memory is a memory store that accurately holds perceptual information for a very brief amount of time. o Iconic memory is the visual form of sensory memory and is held for about one-half to one second. o Echoic memory is the auditory form of sensory memory and is held for considerably longer, but still only about five seconds. o Iconic memory can be detected in a memory experiment: the whole report and partial report conditions. In the whole report condition, researchers flash a grid of latters on a screen for a split second and participants attempt to recall as many as possible – the whole screen. Participants generally can report only three or four of the letters, and those are all in the same line. In the partial report condition, researchers again flash a set of letters on the screen, but the display is followed immediately by a tone that is randomly chosen to be low, medium, or high. After hearing the tone, participants are to report the corresponding line – bottom, middle, or top. Under these conditions, participants still report only three or four of the letters, but they can report them from any randomly selected line. Because the tone comes after the screen goes blank, the only way the participants could get the letters right is if they recalled them from memory. Thus, it was argued that iconic memory could hold all 12 letters as a mental image. o Echoic memory is, for example, when someone asks you a question and you say, “What?” only to realize that you still have the person’s voice in echoic memory – and suddenly say “Oh!” and answer the question before they repeat the question. • Distinguishing Short-Term From Long-Term Memory Stores o Short-term memory (STM) is a memory store with limited capacity and duration (less than a minute). o Long-term memory (LTM) is a memory store that holds information for extended periods of time, if not permanently. o If your class was told to study a list of 15 words and then immediately tried to recall the words, the serial position effect would occur. o The serial position effect is that in general, most people will recall the first few items from a list and the last few items, but only an item or two from the middle. o Proactive interference is when the first information learned occupies memory, leaving fewer resources left to remember the newer information. Yet, we also remember the last few items because they still reside in our STM – a pattern referred to as the recency effect. o The last few items on the list create retroactive interference. o Retroactive interference is when the most recently learned information overshadows some older memories that have not yet made it into long-term memory. • The Working Memory Model: An Active STM System o Rehearsal is when you repeat information until you do not need to remember it anymore. o Working memory is a model of short-term remembering that includes a combination of memory components that can temporarily store small amounts of information for a short period of time. o The working memory model for short-term remembering can be subdivided into three storage components. The phonological loop is a storage component of working memory that relies on rehearsal and stores information as sounds, or an auditory code. The visuospatial sketchpad is a storage component of working memory that maintains visual images and spatial layouts in a visuospatial code. The episodic buffer is a storage component of working memory that combines the images and sounds from the other two components into coherent, story-like episodes. o Working memory also includes one component that is not primarily used for storing information. The central executive is the control center of working memory; it coordinates attention and the exchange of information among the three storage components. It does so by seeking out what is relevant to the person’s goals, interests, and prior knowledge. For example, when you see a series of letters from a familiar alphabet, it is easy to remember the letters by rehearsing them in the phonological loop. How much and how long someone can remember information is affected by the specific information that is being remembered. • The Magical Number 7 o STM can rehearse only seven units of information at once before forgetting something. o Whenever possible, we expand our memory capacity by chunking. o Chunking is when you organize smaller units of information into larger, more meaningful units. For example, when you memorize someone’s telephone number, you memorize the numbers in groups of 3 or 4. • The Phonological Loop o The word-length effect suggests that people remember more one-syllable words than four- or five-syllable words. o The Brown-Peterson test is a technique for measuring the duration of working memory. It relies on two main elements – meaningless stimuli and interference. First, participants read a trigram (unpronounceable series of three letters). Then, they read a three-digit number, and they must count backward (by threes) from the number to interfere with rehearsal (to make sure they cannot repeat the trigram to themselves). They do this until the experimenter says to stop, and at this point, the participants are to report the trigram. Most of the forgetting tends to take place within 15 to 18 seconds. Thus, the duration of the phonological memory is approximately 15 seconds. • The Visuospatial Sketchpad o Feature binding is the process of combining visual features into a single unit. o After visual feature binding, visuospatial memory can accurately retain approximately four whole objects, regardless of how many individual features one can find on those objects. This may be evidence of a second magical number – four. o For example, if you are driving, you probably would not look at a car in front of you and remember images if red, shiny, and smooth. Instead, you would simply have these features bound together in the image of the car, and you would be able to keep track of three or four more such images without much problem. • The Episodic Buffer o The episodic buffer is the most recently hypothesized working memory system and researchers are still examining evidence for and against it. o The episodic buffer seems to hold 7 to 10 pieces of information, which may be combined with other memory stores. o This aspect of its operation can be demonstrated by comparing memory for prose (words strung into sentences) to memory for unrelated words. When people are asked to read and remember meaningful prose, they usually remember 7 to 10 more words than when reading a random list of unrelated words. o Some portion of working memory is able to connect the prose with LTM (knowledge) to increase memory capacity. Because the phonological loop is not doing the binding, some psychologists have proposed that this phenomenon may demonstrate the episodic buffer at work. • Long-Term Memory Systems: Declarative and Nondeclarative Memories o Declarative memories are memories that we are consciously aware of and can be verbalized, including facts about the world and one’s own personal experiences. o Nondeclarative memories include actions or behaviors that you can remember and perform without awareness. Procedural memories are patterns of muscle movements (motor memory), such as how to walk, play piano, or shift gears while driving. Classical conditioning is another type of nondeclarative memory as people can be classically conditioned without awareness. o Declarative memory comes in two varieties. Episodic memories are declarative memories for personal experiences that seem to be organized around “episodes” and are recalled from a first-person (“I” or “my”) perspective. Semantive memories are declarative memories that include facts about the world. Semantic memory is, for example, your knowledge of what a bike is, whereas episodic memory is the memory of when you first (or last) rode a bike, a specific ride that was enjoyable to you, or the last time you rode into a fence. • The Cognitive Neuroscience of Memory o With the behavioral and cognitive aspects of memory, the biopsychosocial model reminds us that everything involves a biological component as well. o Psychologists also look at how the nervous system changes with the formation of new memories, and they examine which areas of the brain are actively involved in remembering. • Memory at the Neural Level o At the neural level, memory formation beings with long-term potentiation. This process underlies the permanent changes that occur across numerous brain cells as memories are forming, strengthening, and being stored. o Long-term potentiation (LTP) means that there is an enduring increase in connectivity and transmission of neural signals between nerve cells that fire together.