Chapter 7 Human Memory

How does information get into memory? How is information maintained in memory? How is information pulled back out of memory?

Human Memory: Basic Questions

Figure 7.2Three key processes in memory. Memory depends on three sequential processes: encoding, storage, and retrieval. Some theorists have drawn an analogy between these processes and elements of information processing by computers, as depicted here. The analogies for encoding and retrieval work pretty well, but the storage analogy is somewhat misleading. When information is stored on a hard drive, it remains unchanged indefinitely and you can retrieve an exact copy. As you will learn in this chapter, memory storage is a much more dynamic process. Our memories change over time and are rough reconstructions rather than exact copies of past events.

The role of attention Focusing awareness

Selective attention = selection of input Filtering: early or late?

Encoding: Getting Information Into Memory

Figure 7.3Models of selective attention. Early-selection models propose that input is filtered before meaning is processed. Late-selection models hold that filtering occurs after the processing of meaning. There is evidence to support early, late, and intermediate selection, suggesting that the location of the attentional filter may not be fixed.

Incoming information processed at different levels: Deeper processing = longer lasting memory codes Encoding levels:

Structural = shallow Phonemic = intermediate Semantic = deep

Levels of Processing: Craik and Lockhart (1972)

Figure 7.4Levels-of-processing theory. According to Craik and Lockhart (1972), structural, phonemic, and semantic encoding—which can be elicited by questions such as those shown on the right—involve progressively deeper levels of processing, which should result in more durable memories.

Elaboration = linking a stimulus to other information at the time of encoding Thinking of examples

Visual Imagery = creation of visual images to represent words to be remembered Easier for concrete objects: Dual-coding theory

Self-Referent Encoding Making information personally meaningful

Enriching Encoding: Improving Memory

Analogy: information storage in computers ~ information storage in human memory

Information-processing theories Subdivide memory into 3 different stores

Sensory, Short-term, Long-term

Storage: Maintaining Information in Memory

Figure 7.2Three key processes in memory. Memory depends on three sequential processes: encoding, storage, and retrieval. Some theorists have drawn an analogy between these processes and elements of information processing by computers, as depicted here. The analogies for encoding and retrieval work pretty well, but the storage analogy is somewhat misleading. When information is stored on a hard drive, it remains unchanged indefinitely and you can retrieve an exact copy. As you will learn in this chapter, memory storage is a much more dynamic process. Our memories change over time and are rough reconstructions rather than exact copies of past events.

Figure 7.8The Atkinson and Shiffrin model of memory storage. Atkinson and Shiffrin (1971) proposed that memory is made up of three information stores. Sensory memory can hold information just long enough (a fraction of a second) for a small portion of it to be selected for longer storage. Short-term memory has a limited capacity, and unless aided by rehearsal, its storage duration is brief. Long-term memory can store an apparently unlimited amount of information for indeterminate periods.

Brief preservation of information in original sensory form Auditory/Visual – approximately ¼ second

George Sperling (1960)Classic experiment on visual sensory store

Sensory Memory

Figure 7.9Sperling’s (1960) study of sensory memory. After the subjects had fixated on the cross, the letters were flashed on the screen just long enough to create a visual afterimage. High, medium, and low tones signaled which row of letters to report. Because subjects had to rely on the afterimage to report the letters, Sperling was able to measure how rapidly the afterimage disappeared by varying the delay between the display and the signal to report.

Limited capacity – magical number 7 plus or minus 2 Chunking – grouping familiar stimuli for storage as a

single unit Limited duration – about 20 seconds without rehearsal

Rehearsal – the process of repetitively verbalizing or thinking about the information

Short Term Memory (STM)

Figure 7.10Peterson and Peterson’s (1959) study of short-term memory. After a warning light was flashed, the subjects were given three consonants to remember. The researchers prevented rehearsal by giving the subjects a three-digit number at the same time and telling them to count backward by three from that number until given the signal to recall the letters. By varying the amount of time between stimulus presentation and recall, Peterson and Peterson were able to measure how quickly information is lost from short-term memory.

STM not limited to phonemic encoding Loss of information not only due to decay Baddeley (1986) – 3 components of working memory

Phonological rehearsal loop Visuospatial sketchpad Executive control system

Short-Term Memory as “Working Memory”

Figure 7.11Short-term memory as working memory. This diagram depicts the revised model of the short-term store proposed by Alan Baddeley (1986), who views STM as a mental scratchpad or temporary workspace. According to Baddeley, working memory includes three components: a phonological rehearsal loop, a visuospatial sketchpad, and an executive control system.

Permanent storage? Flashbulb memories Recall through Hypnosis

Debate: are STM and LTM really different? Phonemic vs. Semantic encoding Decay vs. Interference based forgetting

Long-Term Memory: Unlimited Capacity

Clustering and Conceptual Hierarchies Schemas and Scripts Semantic Networks Connectionist Networks and PDP Models

How is Knowledge Represented and Organized in Memory?

Figure 7.14A semantic network. Much of the organization of long-term memory depends on networks of associations among concepts. In this highly simplified depiction of a fragment of a semantic network, the shorter the line linking any two concepts, the stronger the association between them. The coloration of the concept boxes represents activation of the concepts. This is how the network might look just after a person hears the words fire engine. (Adapted from Collins & Loftus, 1975)

The tip-of-the-tongue phenomenon – a failure in retrieval Retrieval cues

Recalling an event Context cues

Reconstructing memories Misinformation effect

Source monitoring, reality monitoring

Retrieval: Getting Information Out of Memory

Retention – the proportion of material retained Recall Recognition Relearning

Ebbinghaus’s Forgetting Curve

Forgetting: When Memory Lapses

Figure 7.17Ebbinghaus’s forgetting curve for nonsense syllables. From his experiments on himself, Ebbinghaus concluded that forgetting is extremely rapid immediately after the original learning and then levels off. However, subsequent research has suggested that this forgetting curve is unusually steep. (Data from Ebbinghaus, 1885)

Ineffective Encoding Decay theory Interference theory

Proactive Retroactive

Why Do We Forget?

Figure 7.20Retroactive and proactive interference. Retroactive interference occurs when learning produces a “backward” effect, reducing recall of previously learned material. Proactive interference occurs when learning produces a “forward” effect, reducing recall of subsequently learned material. For example, if you were to prepare for an economics test and then study psychology, the interference from the psychology study would be retroactive interference. However, if you studied psychology first and then economics, the interference from the psychology study would be proactive interference.

Encoding Specificity Transfer-appropriate Processing Repression

Authenticity of repressed memories? Controversy

Retrieval Failure

Biochemistry Alteration in synaptic transmission

Hormones modulating neurotransmitter systemsProtein synthesis

Neural circuitry Localized neural circuits

Reusable pathways in the brainLong-term potentiation

Anatomy Anterograde and Retrograde Amnesia

Cerebral cortex, Prefrontal Cortex, Hippocampus,Dentate gyrus, Amygdala, Cerebellum

The Physiology of Memory

Figure 7.24Retrograde versus anterograde amnesia. In retrograde amnesia, memory for events that occurred prior to the onset of amnesia is lost. In anterograde amnesia,memory for events that occur subsequent to the onset of amnesia suffers.

Implicit vs. Explicit Declarative vs. Procedural Semantic vs. Episodic Prospective vs. Retrospective

Are There Multiple Memory Systems?

Improving Everyday Memory

Engage in adequate rehearsal Distribute practice and minimize interference Emphasize deep processing and Transfer-appropriate

processing Organize Information Use Verbal Mnemonics Use Visual Mnemonics

LaunchVideo

Figure 7.26The serial-position effect. After learning a list of items to remember, people tend to recall more of the items from the beginning and the end of the list than from the middle, producing the characteristic U-shaped curve shown here.

Figure 7.27Effects of massed versus distributed practice on retention. Children in the Underwood (1970) study showed better recall of information when practice sessions were distributed over time as opposed to being massed together in one session.