Models of Memory
STEP 4 Review the Knowledge You Need to Score High
IN THIS CHAPTER
Summary: Do you remember how classical conditioning compares with operant conditioning? In order to profit from what you learn, you need to remember it—information from sights, sounds, smells, tastes, and even skin sensations needs to be translated into codes that your brain can store and you can retrieve. Memory is your capacity to register, store, and recover information over time, or, more simply, the persistence of learning over time. Your memory can be affected by how well you focus your attention, your motivation, how much you practice, your state of consciousness when you learn something, your state of consciousness when you recall it, and interference from other events and experiences. Cognitive psychologists study cognition—all the mental activities associated with thinking, knowing, and remembering information.
This chapter looks at how you make memories, remember and forget them, solve problems, and use thinking in your use of language. It also examines test quality, ethics in testing, intelligence and intelligence testing, and the interaction of heredity and environment on intelligence.
In this chapter you’ll also find the answers to the following questions: Why are you given so many test? What makes a “good” test? How do psychologists measure potential or achievement? What are the different theories and measurements of intelligence?
Models of memory
Organization of memories in long-term memory (LTM)
Retrieving stored memories
Standardization and norms
Reliability and validity
Types of tests
Ethics and standards in testing
Kinds of intelligence
Heredity/environment and intelligence
Models of Memory
Different models are used to explain memory. No model accounts for all memory phenomena.
Information Processing Model
The general information processing model compares our mind to a computer. According to this model, input is information. First, input is encoded when our sensory receptors send impulses that are registered by neurons in our brain, similar to getting electronic information into our computer’s CPU (central processing unit) by keyboarding. We must store and retain the information in our brain for some period, ranging from a moment to a lifetime, similar to saving information in our computer’s hard drive. Finally, information must be retrieved upon demand when it is needed, similar to opening up a document or application from the hard drive.
Because we are unable to process all incoming sensory stimulation that is available, we start seeking out, focusing on, and selecting aspects of the available information. Donald Broadbent modeled human memory and thought processes using a flowchart that showed competing information filtered out early, as it is received by the senses and analyzed in the stages of memory. Attention is the mechanism by which we restrict information. Trying to attend to one task over another requires selective or focused attention. We have great difficulty when we try to attend to two complex tasks at once requiring divided attention, such as listening to different conversations or driving and texting. In dichotic listening experiments, participants heard different messages through left and right headphones simultaneously. They were directed to attend to one of the messages and repeat back the words (shadow it). Very little about the unattended message was processed, unless the participant’s name was said, which was noticed (the cocktail party effect). When the cocktail party effect occurred, information was lost from the attended ear. According to Anne Treisman’s feature integration theory, you must focus attention on complex incoming auditory or visual information in order to synthesize it into a meaningful pattern.
According to Fergus Craik and Robert Lockhart’s levels-of-processing theory, how long and how well we remember information depends on how deeply we process the information when it is encoded. With shallow processing, we use structural encoding of superficial sensory information that emphasizes the physical characteristics, such as lines and curves, of the stimulus as it first comes in. We assign no relevance to shallow processed information. For example, once traffic passes and no more traffic is coming, we cross the street. We notice that vehicles pass but don’t pay attention to whether cars, bikes, or trucks make up the traffic and don’t remember any of them. Semantic encoding, associated with deep processing, emphasizes the meaning of verbal input. Deep processing occurs when we attach meaning to information and create associations between the new memory and existing memories (elaboration). Most of the information we remember over long periods is semantically encoded. For example, if you noticed a new red sports car, just like the one you dream about owning, zoom past you with the license plate, “FASTEST1,” and with your English teacher in the driver’s seat, you would probably remember it. One of the best ways to facilitate later recall is to relate the new information to ourselves (self-referent encoding), making it personally meaningful.
A more specific information processing model, the Atkinson—Shiffrin three-stage model of memory, describes three different memory systems characterized by time frames: sensory memory, short-term memory (STM), and long-term memory (LTM; see Figure 9.1). External events from our senses are held in our sensory memory just long enough to be perceived. In sensory memory, visual or iconic memory that completely represents a visual stimulus lasts for less than a second, just long enough to ensure that we don’t see gaps between frames in a motion picture. Auditory or echoic memory lasts for about 4 seconds, just long enough for us to hear a flow of information. Most information in sensory memory is lost. Our selective attention, focusing of awareness on a specific stimulus in sensory memory, determines which very small fraction of information perceived in sensory memory is encoded into short-term memory. Encoding can be processed automatically or require our effort. Automatic processing is unconscious encoding of information about space, time, and frequency that occurs without interfering with our thinking about other things. This is an example of parallel processing, a natural mode of information processing that involves several information streams simultaneously. Effortful processing is encoding that requires our focused attention and conscious effort.
Figure 9.1 Atkinson—Shiffrin three-stage model of memory.
Short-term memory (STM) can hold a limited amount of information for about 30 seconds unless it is processed further. Experiments by George Miller demonstrated that the capacity of STM is approximately seven (plus or minus two) unrelated bits of information at one time. STM lasts just long enough for us to input a seven-digit phone number after looking it up in a telephone directory. Then the number disappears from our memory. How can we get around these limitations of STM? We can hold our memory longer in STM if we rehearse the new information, consciously repeat it. The more time we spend learning new information, the more we retain of it. Even after we’ve learned information, more rehearsal increases our retention. The additional rehearsal is called overlearning. While rehearsal is usually verbal, it can be visual or spatial. People with a photographic or eidetic memory can “see” an image of something they are no longer looking at. We can increase the capacity of STM by chunking, grouping information into meaningful units. A chunk can be a word rather than individual letters or a date rather than individual numbers, for example.
Although working memory is often used as a synonym for STM, Alan Baddeley’s working memory model involves much more than chunking, rehearsal, and passive storage of information. Baddeley’s working memory model is an active three-part memory system that temporarily holds information and consists of a phonological loop, visuospatial working memory, and the central executive. The phonological loop briefly stores information about language sounds with an acoustic code from sensory memory and a rehearsal function that lets us repeat words in the loop. Visuospatial working memory briefly stores visual and spatial information from sensory memory, including imagery, or mental pictures. The central executive actively integrates information from the phonological loop, visuospatial working memory, and long-term memory as we associate old and new information, solve problems, and perform other cognitive tasks. Working memory actively processes visual and auditory information and focuses our attention. Working memory accounts for our ability to carry on a conversation (using the phonological loop) while exercising (using visuo-spatial working memory) at the same time. Most of the information transferred into long-term memory seems to be semantically encoded.
Long-term memory (LTM) is the relatively permanent and practically unlimited capacity memory system into which information from short-term memory may pass. LTM is subdivided into explicit memory and implicit memory. Explicit memory, also called declarative memory, is our LTM of facts and experiences we consciously know and can verbalize. Explicit memory is further divided into semantic memory of facts and general knowledge, and episodic memory of personally experienced events. Implicit memory, also called non-declarative memory, is our LTM for skills and procedures to do things affected by previous experience without that experience being consciously recalled. Implicit memory is further divided into procedural memory of motor and cognitive skills and classical and operant conditioning effects, such as automatic associations between stimuli. Procedural memories are tasks that we perform automatically without thinking, such as tying our shoelaces or swimming. Prospective memory is our memory to perform a planned action or remembering to perform that planned action.
Organization of Memories
How is information in long-term memory organized? Four major models account for organization of LTM: hierarchies, semantic networks, schemas, and connectionist networks. Hierarchies are systems in which concepts are arranged from more general to more specific classes. Concepts, mental representations of related things, may represent physical objects, events, organisms, attributes, or even abstractions. Concepts can be simple or complex. Many concepts have prototypes, which are the most typical examples of the concept. For example, a robin is a prototype for the concept bird, but penguin, emu, and ostrich are not. The basic level in the hierarchy, such as bird in our example, gives us as much detail as we normally need. Superordinate concepts include clusters of basic concepts, such as the concept vertebrates, which includes birds. Subordinate concepts are instances of basic concepts. Semantic networks are more irregular and distorted systems than strict hierarchies, with multiple links from one concept to others. Elements of semantic networks are not limited to particular aspects of items. For example, in a semantic network, the concept of bird can be linked to fly, feathers, wings, animals, vertebrate, robin, canary, and others, which can be linked to many other concepts. We build mental maps that organize and connect concepts to let us process complex experiences. Dr. Steve Kosslyn showed that we seem to scan a visual image of a picture (mental map) in our mind when asked questions. Schemas are preexisting mental frameworks that start as basic operations and then get more and more complex as we gain additional information. These frameworks enable us to organize and interpret new information and can be easily expanded. These large knowledge structures influence the way we encode, make inferences about, and recall information. A script is a schema for an event. For example, because we have a script for elementary school, even if we’ve never been to a particular elementary school, we expect it to have teachers, young students, a principal, classrooms with desks and chairs, and so on. Connectionism theory states that memory is stored throughout the brain in connections between neurons, many of which work together to process a single memory. Changes in the strength of synaptic connections are the basis of memory. Cognitive psychologists and computer scientists interested in artificial intelligence (AI) have designed the neural network or parallel processing model that emphasizes the simultaneous processing of information, which occurs automatically and without our awareness. Neural network computer models are based on neuronlike systems, which are biological rather than artificially contrived computer codes; they can learn, adapt to new situations, and deal with imprecise and incomplete information.
Biology of Long-Term Memory
According to neuroscientists, learning involves strengthening of neural connections at the synapses, called long-term potentiation (or LTP). LTP involves an increase in the efficiency with which signals are sent across the synapses within neural networks of long-term memories. This requires fewer neurotransmitter molecules to make neurons fire and an increase in receptor sites. Where were you when you heard about the 9/11 disaster? Like a camera with a flashbulb that captures a picture of an event, you may have captured that event in your memory. A flashbulb memory, a vivid memory of an emotionally arousing event, is associated with an increase of adrenal hormones triggering release of energy for neural processes and activation of the amygdala and the hippocampus involved in emotional memories.
Evidence from electrophysiology, neuroimaging, computational modeling, and neuropsychology shows that memory function is more integrated rather than isolated in specific brain areas. Although memory is distributed throughout the brain, in multiple memory systems, specific regions are more actively involved in both short-term and long-term memories. The role of the thalamus in memory seems to involve the encoding of sensory memory into short-term memory. STM seems to be located primarily in the prefrontal cortex and temporal lobes. The hippocampus, frontal and temporal lobes of the cerebral cortex, and other regions of the limbic system are involved in explicit long-term memory. Destruction of the hippocampus results in anterograde amnesia, the inability to put new information into explicit memory; no new semantic memories are formed. Another type of amnesia, retrograde amnesia, involves memory loss for a segment of the past, usually around the time of an accident, such as a blow to the head. This may result from disruption of the process of long-term potentiation. Studies using fMRI indicate that the hippocampus and left frontal lobe are especially active in encoding new information into memory, and the right frontal lobe is more active when we retrieve information. A person with damage to the hippocampus can develop skills and learn new procedures. The cerebellum is involved in implicit memory of skills, and studies involving patients with Parkinson’s disease have indicated involvement of basal ganglia in implicit memory too.
Retrieval is the process of getting information out of memory storage. Whenever we take tests, we retrieve information from memory in answering multiple-choice, fill-in, and essay questions. Multiple-choice questions require recognition, identification of learned items when they are presented. Fill-in and essay questions require recall, retrieval of previously learned information. Often the information we try to remember has missing pieces, which results in reconstruction, retrieval of memories that can be distorted by adding, dropping, or changing details to fit a schema.
Hermann Ebbinghaus experimentally investigated the properties of human memory using lists of meaningless syllables. He practiced lists by repeating the syllables and keeping records of his attempts at mastering them. He drew a learning curve. Keeping careful records, he then tested to see how long it took to forget a list. He drew a forgetting curve that declined rapidly before slowing. He found that recognition was sometimes easier than recall to measure forgetting. A method he used to measure retention of information was the savings method, the amount of repetitions required to relearn the list compared to the amount of repetitions it took to learn the list originally. Ebbinghaus also found that if he continued to practice a list after memorizing it well, the information was more resistant to forgetting. He called this the overlearning effect. When we try to retrieve a long list of words, we usually recall the last words and the first words best, forgetting the words in the middle. This is called the serial position effect. The primacy effect refers to better recall of the first items, thought to result from greater rehearsal; the recency effect refers to better recall of the last items. Immediately after learning, the last items may still be in working memory, accounting for the recency effect. We may remember words from the beginning of the list days later because rehearsal moved the words into our LTM.
What helps us remember? Retrieval cues, reminders associated with information we are trying to get out of memory, aid us in remembering. Retrieval cues can be other words or phrases in a specific hierarchy or semantic network, context, and mood or emotions. Priming is activating specific associations in memory either consciously or unconsciously. Retrieval cues prime our memories.
Cramming for a test does not help us remember as well as studying for the same total amount of time in shorter sessions on different occasions. Numerous studies have shown that distributed practice, spreading out the memorization of information or the learning of skills over several sessions, facilitates remembering better than massed practice, cramming the memorization of information or the learning of skills into one session.
If we use mnemonic devices or memory tricks when encoding information, these devices will help us retrieve concepts, for example, acronyms such as ROY G. BIV for colors of the spectrum (red, orange, yellow, green, blue, indigo, violet) or sayings such as “My very educated mother just served us noodles” for the planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune). Another mnemonic, the method of loci, uses association of words on a list with visualization of places on a familiar path. For example, to remember 10 items on a grocery list (chicken, corn, bread, etc.), we associate each with a place in our house (a chicken pecking at the front door, corn making a yellow mess smashed into the foyer, etc.). At the grocery store, we mentally take a tour of our house and retrieve each of the items. Another mnemonic to help us remember lists, the peg word mnemonic, requires us to first memorize a scheme such as “One is a bun, two is a shoe,” and so on, then mentally picture using the chicken in the bun, the corn in the shoe, and so on. These images help both to encode items into LTM and later to retrieve them back into our working memory.
Successful retrieval often depends on the match between the way information is encoded in our brains and the way it is retrieved. The context that we are in when we experience an event, the mood we are in, and our internal state all affect our memory of an event. Our recall is often better when we try to recall information in the same physical setting in which we encoded it, possibly because along with the information, the environment is part of the memory trace; this process is called context-dependent memory. Taking a test in the same room where we learned information can result in greater recall and higher grades. Mood congruence aids retrieval. We recall experiences better that are consistent with our mood at retrieval; we remember information of other happy times when we are happy and information of other sad times when we are unhappy. Finally, memory of an event can be state-dependent; things we learn in one internal state are more easily recalled when in the same state again. Although memory of anything learned when people are drunk is not good, if someone was drunk when he or she hid a gift, he or she might recall where the gift was hidden when he or she was drunk again.
Forgetting may result from failure to encode information, decay of stored memories, or an inability to access information from LTM. Encoding failure results from stimuli to which we were exposed never entering LTM because we did not pay attention to them. For example, most of us cannot remember what is on the front or back of different denominations of money. We use money to pay for things, yet have never paid attention to the details of the coins or paper bills. Decay of stored memories can be explained by a gradual fading of the physical memory trace. We may not remember vocabulary words we learned in a class for a different language several years ago because we have never used that information and the neural connections are no longer there. Relearning is a measure of retention of memory that assesses the time saved compared to learning the first time when learning information again. If relearning takes as much time as initial learning, our memory of the information has decayed.
Cues and Interference
Forgetting that results from inability to access information from LTM can result from insufficient retrieval cues, interference, or motivated forgetting, according to Freud. Sometimes we know that we know something but can’t pull it out of memory; this is called tip-of-the-tongue phenomenon. Often, providing ourselves with retrieval cues we associate with the blocked information can enable us to recall it. Learning some items may prevent retrieving others, especially when the items are similar. This is called interference. Proactive interference occurs when something we learned earlier disrupts recall of something we experience later. Trying to remember a new phone number may be disrupted by the memory of an old phone number. Retroactive interference is the disruptive effect of new learning on the recall of old information. Someone asks us for our old address and it is blocked because our new address interferes with our recall of it.
Hint: Proactive interference is forward-acting. Retroactive interference is backward-acting. If we learn A, then B, and we can’t remember B because A got in the way, we are experiencing proactive interference. If we learn A, then B, and we can’t remember A because B got in the way, we are experiencing retroactive interference.
Sigmund Freud believed that repression (unconscious forgetting) of painful memories occurs as a defense mechanism to protect our self-concepts and minimize anxiety. Freud believed that the submerged memory still lingered in the unconscious mind, and with proper therapy, patience, and effort, these memories could be retrieved. Repressed memories are a controversial area of research today, with Elizabeth Loftus being one of the strongest opponents. She believes that rather than the memory of traumatic events, such as child molestation, being suddenly remembered during therapy, this phenomenon is more a result of the active reconstruction of memory and, thus, confabulation, filling in gaps in memory by combining and substituting memories from events other than the one we are trying to remember. Loftus has found that when we try to remember details at an accident scene, our emotional state, the questions a police officer may ask, and other confusing inconsistencies may result in confabulation. When asked how fast a car was going when it bumped, smashed, or collided into another vehicle, our estimate of the speed would probably differ depending on whether bumped or collided was part of the question. This misinformation effect occurs when we incorporate misleading information into our memory of an event. Forgetting what really happened, or distortion of information at retrieval, can result when we confuse the source of information—putting words in someone else’s mouth—or remember something we see in the movies or on the Internet as actually having happened. This is a misattribution error, also referred to as source amnesia.
Research has shown that we can improve our memory. Applying the information in this section, we can improve our memory for information in AP Psychology by overlearning, spending more time actively rehearsing material, relating the material to ourselves, using mnemonic devices, activating retrieval cues, recalling information soon after we learn it, minimizing interference, spacing out study sessions, and testing our own knowledge.