by DK
Memory types
Where previous psychologists had concentrated on the process of storing information, and the failings of that process, Tulving made a distinction between two different processes—storage and retrieval of information—and showed how the two were linked.
In the course of his research, Tulving was struck by the fact that there seemed to be different kinds of memory. The distinction between long-term memory and short-term memory had already been established, but Tulving felt there was more than one kind of long-term memory. He saw a difference between memories that are knowledge-based (facts and data), and those that are experience-based (events and conversations). He proposed a division of long-term memory into two distinct types: semantic memory, the store of facts; and episodic memory, the repository of our personal history and events.
Tulving’s experiments had demonstrated that organization of semantic information, such as lists of words, helps efficient recollection, and the same appeared to be true of episodic memory. But where semantic memories are organized into meaningful categories of subject matter, episodic memories are organized by relation to the specific time or circumstances in which they were originally stored. For example, a particular conversation may have taken place during a birthday dinner, and the memory of what was said would be stored in association with that occasion. Just as the category of “city” might provide a retrieval cue for the semantic memory “Beijing,” the mention of “40th birthday” might act as a cue for the retrieval of what had been said over that dinner. The more strongly these autobiographical memories are associated with the time and circumstances of their occurrence, the greater their accessibility is likely to be. “Flashbulb memories,” which are stored when a highly memorable event—such as the 9/11 terrorist attacks—occurs, are an extreme example of this.
Tulving described recollection from episodic memory as “mental time travel”, involving us in a revisiting of the past to access the memory. In his later work he pointed out that episodic memory is unique in featuring a subjective sense of time. Specific to humans, it involves not merely awareness of what has been, but also of what may come about. This unique ability allows us to reflect on our lives, worry about future events, and make plans. It is what enables humankind to “take full advantage of its awareness of its continued existence in time” and has allowed us to transform the natural world into one of numerous civilizations and cultures. Through this facility, “time’s arrow is bent into a loop.”
"Remembering is mental time travel."
Endel Tulving
Encoding information
Tulving realized that organization is the key to efficient recall for both semantic and episodic memory, and that the brain somehow organizes information so that specific facts and events are “pigeonholed” with related items. Recalling that specific information is then made easier by direction to the appropriate pigeonhole—the brain “knows where to look” for the memory it wants and can narrow down the search. The implication, he believed, is that the brain encodes each memory for storage in long-term memory, so that specific memories can be located for recollection by a more general retrieval cue. The cues that prompt episodic memory are usually sensory. A specific sound, such as a piece of music, or a scent can trigger a complete memory.
Tulvings’s theory of the “encoding specificity principle” was especially applicable to episodic memory. Memories of specific past events are encoded according to the time of their occurrence, along with other memories of the same time. He found that the most effective cue for retrieving any specific episodic memory is the one which overlaps with it most, since this is stored together with the memory to be retrieved. Retrieval cues are necessary to access episodic memory, but not always sufficient, because sometimes the relationship is not close enough to allow recollection, even though the information is stored and available in long-term memory.
Unlike previous theories of memory, Tulving’s encoding principle made a distinction between memory that is available and that which is accessible. When someone is unable to recall a piece of information, it does not mean that it is “forgotten” in the sense that it has faded or simply disappeared from long-term memory; it may still be stored, and therefore be available—the problem is one of retrieval.
Different types of memory are physically distinct, according to Tulving, because each behaves and functions in a significantly different way.
Scanning for memory
Tulving’s research into the storage and retrieval of memory opened up a whole new area for psychological study. The publication of his findings in the 1970s coincided with a new determination by many cognitive psychologists to find confirmation of their theories in neuroscience, using brain-imaging techniques that had just become available. In conjunction with neuroscientists, Tulving was able to map the areas of the brain that are active during encoding and retrieval of memory, and establish that episodic memory is associated with the medial temporal lobe and, specifically, the hippocampus.
Partly due to his unorthodox and untutored approach, Tulving made innovative insights that proved inspirational to other psychologists, including some of his former students such as Daniel Schacter. Tulving’s focus on storage and retrieval provided a new way of thinking about memory, but it was perhaps his distinction between semantic and episodic memory that was his breakthrough contribution. It allowed subsequent psychologists to increase the complexity of the model to include such concepts as procedural memory (remembering how to do something), and the difference between explicit memory (of which we are consciously aware) and implicit memory (of which we have no conscious awareness, but which nonetheless continues to affect us). These topics remain of great interest to cognitive psychologists today.
Emotional events such as weddings give rise to episodic memories. These are stored in such a way that the person remembering relives the event, in a form of “time travel.”
ENDEL TULVING
Born the son of a judge in Tartu, Estonia, Endel Tulving was educated at a private school for boys, and although a model student, he was more interested in sports than academic subjects. When Russia invaded in 1944, he and his brother escaped to Germany to finish their studies and did not see their parents again until after the death of Stalin 9 years later. After World War II, Tulving worked as a translator for the American army and briefly attended medical school before emigrating to Canada in 1949. He was accepted as a student at the University of Toronto, where he graduated in psychology in 1953, and took his MA degree in 1954. He then moved to Harvard where he gained a PhD for his thesis on visual perception. In 1956, Tulving returned to the University of Toronto, where he continues to teach to this day.
Key works
1972 Organization of Memory
1983 Elements of Episodic Memory
1999 Memory, Consciousness, and the Brain
See also: Hermann Ebbinghaus • Bluma Zeigarnik • George Armitage Miller • Gordon H. Bower • Elizabeth Loftus • Daniel Schacter • Roger Brown • Frederic Bartlett
IN CONTEXT
APPROACH
Perception
BEFORE
1637 René Descartes in his treatise Discourse on the Method suggests that though our senses can be deceived, we are thinking beings with innate knowledge.
1920s Gestalt theorists study visual perception, finding that people tend to view objects comprising composite parts as a unified whole.
1958 Donald Broadbent’s book Perception and Communication introduces a truly cognitive approach to the psychology of perception.
AFTER
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br /> 1986 American experimental psychologist Michael Kubovy publishes The Psychology of Perspective and Renaissance Art.
How the mind makes use of information gathered from the external world has been a major concern for philosophers and psychologists throughout history. Exactly how do we use the information gained through our senses? In the early 1970s, cognitive and mathematical psychologist Roger Shepard proposed new theories of how the brain processes “sense data.”
Shepard argued that our brains not only process sense data, but also make inferences from it, based on an internal model of the physical world where we can visualize objects in three dimensions. The experiment he used to prove this, in which subjects tried to ascertain whether two tables—each drawn from a different angle—were the same, showed that we are able to perform what Shepard called “mental rotation:” turning one of the tables in our mind’s eye for comparison.
Shepard used a series of optical (and aural) illusions to demonstrate that our brains interpret sense data using both knowledge of the external world and mental visualization. Perception, Shepard said, is “externally guided hallucination,” and he described the processes of dreaming and hallucination as “internally simulated perception.”
Shepard’s research introduced revolutionary techniques for identifying the hidden structure of mental representations and processes. His work in visual and auditory perception, mental imagery, and representation has influenced generations of psychologists.
An optical illusion creates confusion in the viewer, demonstrating that we are not just perceiving, but also attempting to fit the sensory data to what we already understand in the mind’s eye.
See also: René Descartes • Wolfgang Köhler • Jerome Bruner • Donald Broadbent • Max Wertheimer
IN CONTEXT
APPROACH
Prospect theory
BEFORE
1738 The Dutch-Swiss mathematician Daniel Bernoulli proposes the expected utility hypothesis to explain decision-making preferences in situations involving risk.
1917 Wolfgang Köhler publishes The Mentality of Apes—his study of problem-solving in chimpanzees.
1940s Edward Tolman’s studies on animal behavior open up a new area of research into motivation and decision-making.
AFTER
1980 US economist Richard Thaler publishes the first paper on the subject of behavioral economics: Toward a Positive Theory of Consumer Choice.
Until very recently, our perception of risk and the way that we make our decisions was considered to be more a matter of probability and statistics than psychology. However, cognitive psychology, with its emphasis on mental processes, brought the concepts of perception and judgment to the field of problem-solving, with some surprising results.
Israeli-American Daniel Kahneman, with Amos Tversky, reexamined theories of how we make decisions when faced with uncertainty, in Judgment under Uncertainty: Heuristics and Biases (1974). They found the general belief that people made decisions based on statistics and probability was not true in practice. Instead, people base their decisions on “rule of thumb”—on specific examples or small samples. Consequently, judgments can frequently be wrong, as they are based on information that comes easily to mind, rather than that has actual probability.
"After observing a long run of red on the roulette wheel, most people erroneously believe that black is now due."
Daniel Kahneman & Amos Tversky
Kahneman and Tversky noticed this experience-based method of problem-solving has a pattern: we tend to overestimate the likelihood of things with low probability (such as a plane crash), and underestimate those with a higher probability (such as crashing while driving drunk).
These findings formed the basis of Kahneman and Tversky’s prospect theory, proposed in 1979, and led to the collaborative field of psychology known as behavioral economics.
See also: Edward Tolman • Wolfgang Köhler
IN CONTEXT
APPROACH
Memory studies
BEFORE
1927 Bluma Zeigarnik describes the “Zeigarnik effect” of interrupted tasks being better remembered than uninterrupted ones.
1956 George Armitage Miller’s The Magical Number 7, Plus or Minus 2 provides a cognitive model for storage in short-term memory.
1972 Endel Tulving makes a distinction between semantic and episodic memory.
AFTER
1977 Roger Brown coins the term “flashbulb memory” for autobiographical memory connected with highly emotional events.
2001 Daniel Schacter publishes The Seven Sins of Memory, which categorizes the ways that memory can fail.
The 1950s saw a revival of interest in the study of memory. Increasingly sophisticated models of short- and long-term memory were developed, in order to explain how information is selected, organized, stored, and retrieved. The ways in which memories could be forgotten or distorted were also identified.
Memory and mood
By the 1970s, the focus in learning theory and memory had moved to investigating why some memories are better stored or more easily retrieved than others. One of the foremost psychologists in the field, Gordon H. Bower, had noticed that emotion appeared to impact on memory. Bower carried out studies in which people learned lists of words while in different moods, and later had to recall them, again when in varying emotional states. He uncovered what he called “mood-dependent retrieval:” whatever a person has learned when unhappy is easier to recall when they are again unhappy. Bower concluded that we form an association between our emotional state and what is going on around us, and the emotion and the information are stored in memory together. It is then easier to recall facts that we learned when we were in the same mood as we are when recollecting them.
"People who are happy during the initial experience learn the happy events better; angry people learn anger-provoking events better."
Gordon H. Bower
Bower also discovered that emotion plays a part in the type of information that the brain stores. When we are happy, he observed that we tend to notice—and therefore remember—positive things; when we are sad, negative things attract our attention and are committed to memory more easily. For example, Bower found that unhappy people recalled details of a sad story better than those who were happy when they read it. He called this “mood-congruent processing,” and concluded that episodic memory—of events, not just words or facts—is especially linked to emotions. The events and emotions are stored together, and we remember best the events that match our mood, both when they occurred, and when recalling them.
Bower’s findings led him to study people in various emotional states, retrospectively observing their videotaped interactions with others. Memory and judgement of past behavior varied with current mood. This research helped Bower to refine his ideas about emotion and memory, and inspired further psychological examination of the role emotions play in our lives.
An idyllic vacation, according to Bower, is more easily recalled when we are in a happy mood. Bad memories of the trip are likely to be forgotten, or only remembered when we are unhappy.
GORDON H. BOWER
Gordon H. Bower was brought up in Scio, Ohio. At high school, he was more interested in baseball and playing jazz than studying, until a teacher introduced him to the works of Sigmund Freud. He went on to graduate in psychology at Case Western Reserve University, Cleveland, switching to Yale for his PhD in learning theory, which he completed in 1959.
From Yale, Bower moved on to the internationally acclaimed psychology department of Stanford University, California, where he taught until his ret
irement in 2005. His research there helped to develop the field of cognitive science, and in 2005 Bower was awarded the US National Medal of Science for his contributions to cognitive and mathematical psychology.
Key works
1966, 1975 Theories of Learning (with Ernest Hilgard)
1981 Mood and Memory
1991 Psychology of Learning and Motivation (Volume 27)
See also: Bluma Zeigarnik • George Armitage Miller • Endel Tulving • Paul Ekman • Daniel Schacter • Roger Brown
IN CONTEXT
APPROACH
Psychology of emotions
BEFORE
1960s The study of isolated tribal communities by American anthropologist Margaret Mead suggests that facial expressions are culture-specific.
1960s American psychologist Silvan Tomkins (Ekman’s mentor) proposes his Affect Theory of Emotions, distinct from the basic Freudian drives of sex, fear, and the will to live.
1970s Gordon H. Bower uncovers and defines the links between emotional states and memory.
AFTER
2000s The findings of Ekman’s work on facial expressions and deception are incorporated into security procedures used by public transport systems.
Emotions, and more especially emotional disorders, played a large part in psychotherapy from its beginnings, but they were seen more as symptoms to be treated than as something to be examined in their own right. One of the first to realize that emotions deserved as much attention as thought processes, drives, and behavior was Paul Ekman, who came to the subject through his research into nonverbal behavior and facial expressions.
