Chapter 8: Memory
ACQUISITION, STORAGE, RETRIEVAL
- Any act of remembering begins with acquisition, the process of gathering information and placing it into memory. The next aspect of memory is storage, the holding of information in some enduring form in the mind for later use. The final phase is retrieval, the point at which we draw information from storage and use it in some fashion.
- Memory acquisition includes cases of intentional learning and incidental learning. In either case, the person must pay attention to the material to be remembered, and it is the product of this intellectual engagement that is stored in memory.
- According to the stage theory of memory, information is held in working memory while one is thinking about it, but it’s lodged in long-term memory for storage for longer intervals. This theory is supported by studies of free recall.In these studies, primacy effects reflect the fact that early items in a presentation receive more rehearsal and are more likely to be transferred to long-term storage. Recency effects reflect the fact that just-heard items can be retrieved directly from working memory.
- Chunking is the process through which items are recoded into a smaller number of larger units. The active nature of memory is also evident in the fact that mere maintenance rehearsal does little to promote long-term storage.
- According to many studies, how well someone remembers will depend on the depth at which he or she processed the incoming information; shallow processing refers to encoding that emphasizes the superficial characteristics of a stimulus, and deep processing refers to encoding that emphasizes the meaning of the material.Consistent with this perspective, we remember best the material that we’ve understood, thanks to the memory connections linking one memory to the next. At the time of recall, these connections serve as retrieval paths.
- Mnemonics help a person form memory connections, and these connections can dramatically improve memory. Many mnemonics utilize imagery, and imagery is most helpful if the visualized items are imagined in some interaction—linking the items to each other, as one would expect if imagery is a means of promoting memory connections.
- More research is needed to explore how the memory trace is actually represented in the brain. However, evidence suggests that different elements of a single memory (what things looked like, how one felt) may be stored in different brain sites.
- The establishment of a long-term memory depends on a memory consolidation process, during which new connections are formed among neurons. The need for consolidation is reflected in cases in which this process has been disrupted, resulting in retrograde amnesia.
- The retrieval of memories is often easy, but it sometimes fails. The failure can be complete or can be partial, as in the tip-ofthe- tongue effect. The retrieval of memories is often promoted by our having an appropriate retrieval cue. Whether a cue is useful depends on whether the cue re-creates the context in which the original learning occurred. This context reinstatement allows the person to use the connections they formed earlier as retrieval paths.
- What’s stored in memory reflects how the person thought about or reacted to the object or event being remembered. This encoding specificity is reflected in the fact that remembering is more likely if one thinks about the target information during retrieval in the same way that one did during encoding.
MEMORY GAPS, MEMORY ERRORS
- Many cases of forgetting can be understood as the result of inadequate encoding. This is reflected in the fact that fMRI data, collected during encoding, show different patterns for later-remembered material and later-forgotten material.
- Forgetting generally increases as the retention interval gets longer, but the causes of forgetting are still being debated. One theory holds that traces gradually decay. Another view argues that the cause of forgetting is interference produced by other memories. In some cases, this is because the other memories promote retrieval failure—an inability to find information that’s nonetheless still in storage. Retrieval fail- ure is evident whenever some new cue allows us to recall previously forgotten materials.
- Interference can also result from the mixing together of memories. These intrusion errors are evident in the misinformation effect, in which specific episodes are blurred together. In other cases, intrusion errors are the result of schematic knowledge intruding into someone’s memory of a particular event. This reflects a broader pattern of evidence indicating that events are usually understood (and remembered) with reference to knowledge structures called schemas.
- Intrusion errors can also be produced by semantic associations with the material being recalled. This is the source of the errors often observed in the DRM paradigm.
- Another category of memory errors involves cases in which someone correctly realizes that an idea (or face or stimulus) is familiar, but makes an error about why the idea is familiar. This pattern reflects the fact that separate memory systems are the bases for familiarity and recollection.
- Psychologists have searched unsuccessfully for ways of distinguishing correct memories from mistaken ones. The confidence expressed by the person remembering turns out to be of little value for this discrimination. Hypnosis also does nothing to improve memory and can actually increase the risk of memory error.
VARIETIES OF MEMORY
- Researchers find it useful to distinguish several types of memory. Episodic memories concern specific episodes; semantic memories concern broader knowledge, not tied to a particular episode. Explicit memories are consciously recalled; implicit memories are revealed when there is an effect of some past experience without the person being aware that she’s remembering at all—or even that there was a relevant past experience.
- Some theorists subdivide episodic memory, distinguishing autobiographical memories from memories for other episodes, and placing flashbulb memories or traumatic memories into their own category. However, current evidence suggests that flashbulb memories are governed by the same principles as other memories, and the same is true for traumatic memories—although debate continues over the possible role of “repression” or “dissociation” in memory for traumatic events.
- Certain injuries to the brain produce anterograde amnesia, in which the patient’s ability to fix material in long-term memory is reduced. However, someone with amnesia may still have intact implicit memories.Implicit memories, in turn, can be divided into several types: procedural memories, involving changes in behavior, priming, changing our perceptions and thoughts, and perceptual learning.