- Articulatory suppression:
- A technique for disrupting verbal rehearsal by requiring participants to continuously repeat a spoken item.
- The process of combining a number of items into a single chunk typically on the basis of long-term memory.
- Corsi block tapping:
- Visuo-spatial counterpart to digit span involving an array of blocks that the tester taps in a sequence and the patient attempts to copy.
- Digit span:
- Maximum number of sequentially presented digits that can reliably be recalled in the correct order.
- Free recall:
- A method whereby participants are presented with a sequence of items which they are subsequently required to recall in any order they wish.
- Irrelevant sound effect:
- A tendency for verbal STM to be disrupted by concurrent fluctuating sounds, including both speech and music.
- Long-term recency:
- A tendency for the last few items to be well recalled under conditions of long-term memory.
- Phonological loop:
- Term applied by Baddeley and Hitch to the component of their model responsible for the temporary storage of speech-like information.
- Phonological similarity effect:
- A tendency for immediate serial recall of verbal material to be reduced, when the items are similar in sound.
- Primacy effect:
- A tendency for the first few items in a sequence to be better recalled than most of the following items.
- Recency effect:
- A tendency for the last few items in a list to be well recalled.
- Visuo-spatial STM:
- Retention of visual and/or spatial information over brief periods of time.
- Word length effect:
- A tendency for verbal memory span to decrease when longer words are used.
- Working memory span:
- Term applied to a range of complex memory span tasks in which simultaneous storage and processing is required.
Research activity 1: chunking
Miller (1956) suggested that what we can remember is not dependent on the number of items, but on the number of meaningful chunks we can create out of those items. Try recalling each of the following sequences of nine letters one by one. Read the letters then close your eyes and try to recall them in the correct order.
Presumably you found the first one the easiest to do, followed by the second, then the third?As most people know the word NEWSPAPER and how to spell it, in the first case you only have to remember one chunk;what the word is. In the second case, although the word is nonsense it could plausibly be an English word. We can therefore break it down into syllables that already exist in the English language, e.g. SPA – WEN – PER. In this example we only need to remember three chunks in the correct order. In the final example the letters do not resemble any structure that we are familiar with in the English language. We therefore need to remember each letter and its position in the sequence individually, i.e. nine items.
Research activity 2: memory span
Below are 12 noun words. Read through them once (out loud), then look away and write down how many you can remember. Once you’ve finished (give yourself no more than a couple of minutes), look at the list again and check how many you have got right.
The average memory span for this sort of free recall task is typically between five and nine words. However, also make note of where the words you remembered were in the sequence you read them. Usually people are more likely to remember the first three and last three words. This is known as the primacy–recency effect and is viewed as evidence for long-term and short-term memory components to our memory.
- Videos of Alan Baddeley talking about various aspects of the working memory model.
- A demo where you can try the digit span test.
- An instruction video for the digit span task.
Please find below biographies of four important researchers in the field of memory: George Armitage Miller, Brenda Milner, Steven J. Luck, and Martha Farah.
George Armitage Miller
George Armitage Miller, born on February 3, 1920, called Charleston, West Virginia home prior to attending George Washington University and then transferring to the University of Alabama, where he received his Bachelor of Arts degree in 1940 and his Master’s a year later. At that point, he began a 2-year stint as an Instructor in Psychology at his alma mater before enrolling in Harvard University’s Ph.D. program as a student in the Psycho-Acoustical Laboratory.
At Harvard University, he studied speech production and perception and evaluated radio-telephone systems for the US Army, and, in 1946, he defended his work on speech masking. His subsequent lectures at Harvard formed the basis for his book, Language and Communication. Following this, he studied mathematics at Princeton University and moved to MIT before returning to Harvard in 1955 as an Associate Professor of Psychology. In collaboration with J.S. Bruner, Miller, by then a full professor, helped found the Harvard Center for Cognitive Studies in 1960 and was elected to the National Academy of Science 2 years later.
From 1963 to 1964, Miller was a Fulbright Research Fellow at Oxford University. After a year as a visiting scholar at the Rockefeller University in New York, Miller decided to accept a position as a Professor of Experimental Psychology there in 1968. A decade following his election as President of the American Psychological Association in 1969, Miller joined the faculty at Princeton University, where he held the position of the James S. McDonnell Distinguished University Professor of Psychology, Emeritus. Miller founded the Princeton Cognitive Science Laboratory, and, for a time between 1989 and 1994, he served as Program Director of the McDonnell-Pew Program in Cognitive Neuroscience, receiving the National Medal of Science in 1991. He died in 2012, at his home in Plainsboro, New Jersey, of complications of pneumonia and dementia.
Miller’s early research at Harvard was shaped by C.E. Shannon’s mathematical theory of communication, leading Miller to investigate how expectations influence speech perception. His 1951 publication of Language and Communication catapulted the study of psycholinguistics into a full-fledged area of psychology. Miller’s Law states that in order to understand another person’s statement, the listener must assume that the proposition is true and try to imagine what it could be true of, based on presuppositions. His attempt to quantify information and the capacity of short-term memory gave rise to the notion that most adults could remember around seven information chunks, give or take a couple of items. This limitation can be circumvented to some extent by chunking information into larger groups. These ideas were
Miller’s interest in grammar and, later, the lexicon, resulted in a collaboration with P.N. Johnson-Laird, with whom he developed a hypothesis about how words are stored in long-term memory, a topic he later researched in relation to how children acquire language. In 1985 Miller founded WordNet, an English language semantic network that attempts to model how the human mind stores and implements language. Since then he has continued to work on its development and this work has been adopted into machine-based translation services and Internet searches—in fact Simpli, an early search engine designed to parse search queries and scour webpages for relevant keywords, can be credited as the basis for Google’s AdSense technology.
Miller, G. A. (1947). The masking of speech. Psychological Bulletin, 44, 104–109.
Miller, G. A. (1951). Language and communication. New York: McGraw-Hill.
Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81–97.
Miller, G. A. (1995). WordNet: A Lexical Database for English. Communications of the ACM 38(11), 39–41.
Brenda Milner was born Brenda Langford on July 15, 1918 in Manchester, England. Milner’s father tutored her in mathematics and the arts from an early age, until her father died when Brenda was 8 years old. After attending Withington Girls’ School, she enrolled at Newnham College, Cambridge University, to study mathematics in 1936, with the help of a scholarship and a small grant. After only a year, she switched her concentration to the relatively young and unfamiliar field of psychology, which came as a disappointment to her mother.
While at Cambridge, Dr Oliver Zangwill advised Milner, instilling in her an appreciation for studying the behavioral deficits associated with particular brain lesions in order to understand normal brain functioning. In 1939, with her Bachelor’s degree in the moral sciences, she won a Sarah Smithson Research Studentship from Newnham College, allowing her to continue on at Bartlett’s Cambridge Psychological Laboratory in pursuit of her Master’s degree.
World War II’s outbreak shifted her research topic to the use of aptitude tests to differentially identifying fighter pilots and bomber pilots for the war effort. She would also help with the war effort by working for the Ministry of Supply in Malvern to develop methods for radar operators between 1941 and 1944. In 1944, she met Peter Milner, an electrical engineer. They were soon married, which was followed by a move to Montreal, Quebec in Canada due to a job offer for Peter. Although they only intended to remain there for a year, the move became permanent.
Milner, who needed no time to learn French, landed a position at the Université de Montréal’s Institut de Psychologie. She researched and taught there beginning in 1944. Donald Hebb, then in charge of the department of psychology at McGill University, allowed Milner to attend a weekly seminar in which they discussed his Organization of Behavior, then only in manuscript form. Though she would continue to teach at the Université de Montréal until 1952, Brenda Milner became a graduate student under Hebb in 1949. Thanks to a connection Hebb had with Wilder Penfield’s neurosurgery patients at the Montreal Neurological Institute, three years after graduating with her Ph.D. in experimental psychology in 1952, Milner made the acquaintance of a neurosurgery patient known as HM who had acquired amnesia from medial temporal lobectomy, about whom she would first write in a landmark paper with Scoville in 1957.
She remained at the Montreal Neurological Institute following graduation, and currently holds the title of Dorothy J. Killam Professor of Psychology in the Department of Neurology and Neurosurgery at McGill University. Following a one-year sabbatical, Milner earned her Doctorate of Science from Cambridge in 1972. Milner is a fellow of the American Psychological Association and of the Royal Societies in both London and Canada. A member of the National Academy of Sciences, Milner was made an Officer of the Order of Canada in 1984 and was promoted to Companion in 2004. The same year she also received the Neuroscience Award from the National Academy of Science in the United States.
Milner, perhaps best known for her work with amnesic patient HM, was a forerunner in the study of the mnemonic effects of medial temporal lobe damage. She described how individuals afflicted with medial temporal lobe amnesic syndrome are unable to acquire new, declarative memories, though other cognitive abilities are generally spared, including motor skill acquisition. Thus, her work served to highlight, for the first time, the existence of multiple memory systems within the brain. Specifically, she linked declarative memories to the cortico-limbic pathways, rather than the cortico-basal ganglia pathways crucial in the acquisition of skills and procedural memories.
Although her early work centered on patients with damage to the medial temporal lobes, she also investigated the role of the frontal lobes in the organization of memories. For instance, she discovered that the dorsolateral prefrontal cortex is important in ordering memories temporally and that damage to the frontal lobe is associated with perseveration and other types of cognitive inflexibility. Milner’s research not only demonstrated the deficits resulting from damage to particular brain regions, but also convincingly showed that neural processes can be reorganized in the wake of brain damage.
Milner appreciated how different individuals responded differently to brain damage in the same region. For instance, she noted that language in left- and right-handed people (as well as the ambidextrous) is differentially lateralized. The improved understanding of hemispheric lateralization provided by Milner has guided therapy for patients suffering from stroke and Alzheimer’s disease. Given that individuals respond differently to lesions, Milner developed a technique to temporarily disrupt brain activity in selected areas by administering sodium amytal in order to determine the functions associated with that brain region. This method is now commonly used to guide brain surgeries across the globe and has helped reduce the extent of linguistic and cognitive surgical side effects.
Recently, Milner has started conducting neuroimaging studies with healthy participants to identify brain regions subserving spatial memory and language.
Milner, B., Taylor, L., & Sperry, R. W. (1968). Lateralized suppression of dichotically-presented digits after commissural section in man. Science, 161, 184–186.
Scoville, W. B., & Milner, B. (1957). Loss of recent memory after bilateral hippocampal lesions. Journal of Neurology, Neurosurgery and Psychiatry, 20, 11–21.
Branch, C., Milner, B., & Rasmussen, T. (1964). Intracarotid sodium amytal for the lateralization of cerebral speech dominance. Journal of Neurosurgery, 21, 399–405.
Köhler, S., Joelle, C., & Milner, B. (2002). Differential contributions of the parahippocampal place area and the anterior hippocampus to human memory for scenes. Hippocampus, 12(6), 718–723.
Steven J. Luck
Steve Luck was born in Madison, Wisconsin in 1963 and quickly acquired a penchant for comic books and playing the guitar in rock bands. In 1981, Luck went to Reed College to study psychology, in hopes of becoming a successful clinical psychologist who could draw from his interest in philosophy. Professor Allen Neuringer’s introductory psychology class and subsequent methods class piqued his interest in memory and learning research.
In his sophomore year, he, with another student, Marianne Colgrove, completed a series of experiments on sequence learning in pigeons that would result in a publication in the journal Animal Learning & Behavior. His work required a level of familiarity with the UNIX operating system and the BASIC computer programming language, both of which would prove beneficial in the high-tech field of cognitive neuroscience. At the end of his sophomore year, he was offered a position in Dr Martha Neuringer’s lab at the Oregon. This experience first exposed Luck to electrophysiological recordings that would become central to his later research career.
The following year, Prof Dell Rhodes commissioned Luck to design a computer program for recording ERPs in humans. Rhodes would continue to mentor Luck through his own ERP experiments, leading to Luck’s senior thesis, called “The effects of attention, task-relevance, and sequence variability on cognitive-event related brain potentials.” Luck graduated in 1986, which was followed by a move to the University of California, San Diego to work on visual selective attention in Steve Hillyard’s neuroscience laboratory. While pursuing his Ph.D. with the help of a National Science Foundation Graduate Fellowship, he visited Bob Desimone’s laboratory at the National Institutes of Health for 7 months from 1992 to 1993 to conduct additional research.
Luck graduated in 1993, though he stayed in Hillyard’s laboratory for another year as a postdoctoral fellow before accepting a position as an assistant professor at the University of Iowa’s Department of Psychology. He remained at the University of Iowa until 2006, reaching full professor status in 2002. Currently he is a Professor of Psychology at the University of California, Davis.
Among other honors, Luck is a recipient of the American Psychological Foundation’s FJ McGuigan young Investigator Prize (2002), the Troland Award in Experimental Psychology from the National Academy of Sciences (2001), and the American Psychological Association’s Distinguished Scientific Award for Early Career Contribution to Psychology in the area of Behavioral and Cognitive Neuroscience (1998/1999).
Luck’s work at the Oregon Regional Primate Research Center found evidence for the concern that the lack of omega-3 fatty acids in many commercial infant formulas at the time affects the electrophysiological responses of the retina and the organism’s corresponding visual acuity.
Luck’s subsequent research has been, generally, less applied. In graduate school, Luck studied when and where attention acts on mental processing. Using ERP recordings from his human subjects as they completed psychophysical tasks, Luck demonstrated that under some circumstances, attention influences early, sensory processing. He continued researching this topic during his time in Bob Desimone’s laboratory, this time by recording the electrical activity of individual neurons in monkey visual cortex during visual attention tasks. He found that attention enhanced neural activity in extrastriate visual cortex, compared to activity for ignored stimuli.
A good deal of Luck’s research focuses on the visual search task. In this task, participants have to find a target object in an array of distractor objects. He discovered that there is a particular ERP signature corresponding to the focusing of attention on a target that also helps suppress the activation of competitors. His Ambiguity Resolution Theory of Visual Attention attempts to link behavioral and electrophysiological recordings of attentional processes in humans and monkeys.
Kim Shapiro, Luck’s graduate student named Ed Vogel, and he would also use the ERP technique to study the attentional blink, in which participants fail to detect the second of two targets in a rapid stream of stimuli, provided that they’re presented at a certain lag. Their experiments helped determine that participants are unable to report seeing the target because of a working memory failure, despite having fully identified it. Luck’s research supports the existence of multiple, partially-independent subsystems of attention, operating at different stages of processing. Luck, Vogel, and Geoff Woodman, another graduate student, went on to study the capacity of visual working memory (about three or four items defined by simple features or combinations of features).
Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390, 279–281.
Woodman, G. F., Vogel, E. K., & Luck, S. J. (2001). Visual search remains efficient when visual working memory is full. Psychological Science, 12,219–224.
.Zhang, W., & Luck, S. J. (2008). Discrete fixed-resolution representations in visual working memory. Nature, 453, 233–235.
Martha Farah earned her Bachelor’s degree in Metallurgy and Material Science, as well as Philosophy from the Massachusetts Institute of Technology in 1977 before pursuing her Ph.D. in Experimental Psychology from Harvard University, which she received in 1983. Her postdoctoral studies were carried out between 1983 and 1985 at MIT and Boston University School of Medicine, where she was trained in neuropsychology. Her first academic appointment was at Carnegie Mellon University, beginning in 1985 and culminating with her promotion to full Professor of Psychology by the time she transitioned to the University of Pennsylvania in 1992.
Currently she holds numerous positions at Penn, including being the Walter H. Annenberg Professor in Natural Sciences, Professor of Psychology, Adjunct Professor of Neurology. Additionally, she served as the Director of the Center for Cognitive Neuroscience from 1999 to 2010, and is now Director of the Center for Neuroscience & Society. In 2008 she received the William James Fellow lifetime achievement award from the Association for Psychological Science. In 2010 she became a Fellow of the American Academy of Arts and Sciences, and in 2013 she received a Science Educator Award from the Society for Neuroscience.
Farah’s early research was largely based on her work with neuropsychological patients, examining their specific deficits in the areas of vision, memory, and executive control and relating that back to the underlying brain damage. During this time, she made numerous dissociations between patient groups, such as visual agnosics, who have difficulty identifying objects visually, while their spatial abilities are largely intact.
Her book, Visual Agnosia: Disorders of Object Recognition and What They Tell Us about Normal Vision, remains an important resource in the domain to this day. Additionally, she has worked with patients who have profound difficulties recognizing faces, a condition called prosopagnosia, and individuals who tend to neglect one half of the visual field, even though their visual system is in working order. Moreover, she has helped identify the brain region that supports visual imagery—namely the posterior left hemisphere.
Noticing that brain-damaged patients often have selective deficits for living things, rather than nonliving objects, Farah and McClelland (1991) developed a sensory-functional theory of semantic memory, in which objects are categorized in terms of their visual or functional properties. This theory further holds that because living things are primarily distinguished based upon their perceptual, rather than functional, properties, and because there are thought to be more visual units in the semantic system, they are more likely to be damaged, resulting in poorer performance for living objects.
Farah has used modern neuroimaging techniques to examine the neural bases of the cognitive abilities in normal adults with great success; however, in a recent shift, she has turned the primary focus of her attention to neuroethics (i.e., the ethical issues that have arisen during the development of the neuroscience of cognition and emotion) and how socioeconomic factors affect brain development. Additionally, she and her collaborators have been studying the ability to regulate mood and cognition and to engage in decision making.
Farah, M. J. (1994). Neuropsychological inference with an interactive brain: A critique of the ‘locality assumption’. Behavioral & Brain Sciences, 17, 43–61.
Farah, M. J., Wilson, K. D., Drain, M., & Tanaka, J. N. (1998). What is ‘special’ about face perception? Psychological Review, 105, 482–498.
Farah, M. J., & Aguirre, G. K. (1999). Imaging visual recognition: PET and fMRI studies of functional anatomy of human visual recognition. Trends in Cognitive Sciences, 3, 179–186.
Farah, M. J. (2002). Emerging ethical issues in neuroscience. Nature Neuroscience, 5, 1123–1129.