Chapter 7: Human Memory

Chapter 7: Human Memory.

There are two types of memory, one for general info & memory for personal events called semantic and episodic memory.

- Encoding: involves forming a memory code & getting info in.

-Storage: involves maintaining encoded information in memory over time.

-Retrieval: involves recovering information from memory stores.

Encoding: Requires attention; the role of attention involves focusing awareness on a narrowed range of stimuli or events.

(Often linked to a “filter” that screens out most potential stimuli while allowing a select few to pass through conscious awareness.)

Model of selective attention:

STIMULUS -> SENSORY DETECTION -> RECOGNITION OF MEANING (early – late) -> RESPONSE SELECTION -> RESPONSE

[Evidence suggests that we may be able to place the filter up and down anywhere between the (early-late) extremes.]

• People deal w/ 3 progressively deeper levels of processing:

1: structural encoding – relatively shallow processing that emphasizes the physical structure of the stimulus. (e.g. if word were flashed on a screen, registers such things as now they were printed or the length of the words.)

2: phonemic encoding – emphasizes what the word sounds like and involves naming or saying (perhaps silently) the words.

3: semantic encoding – emphasizes the meaning of the verbal input; it involves thinking about the objects and actions of the word represent.

• Levels-of-processing theory – proposes that deeper levels of processing result in longer lasting memory codes.
• Elaboration – linking a stimulus to other information at the time of encoding. [Often consists of thinking of examples that illustrate an idea.]
• Imagery (visual imagery) – creation of visual images to represent the words to be remembered and also enrich encoding, such as examples of an idea.
• Dual encoding theory – holds that memory is enhanced by forming semantic and visual codes, since either can lead to recall.
• Self- referent encoding – involves deciding how or whether information is personally relevant. (People’s recall of info tends to be slanted in favors of material personally relevant.)

Information-processing theories subdivided memory into 3 separate memory stores.

1: sensory memory: preserves information in its original sensory form for a brief time, usually only a fraction of a second.

-Allows the sensation of a visual pattern, sound or touch to linger for a brief moment after the sensory stimulation is over.

-In the case of vision, you perceive an after image rather than the actual stimulus.

-Memory trace in the visual sensory decays approx. ¼ of a second & traces in the auditory sensory store appear to last less than one second.

2: short term memory: limited-capacity store that can maintain unrehearsed information for up to 20 seconds.

-You can maintain info in your short-term memory by engaging in rehearsal: the process of repetitively verbalizing or thinking about the information. (Without rehearsal info is lost in less than 20 seconds)

-Short-term memory is also limited in the number of items it can hold.

-You can increase the capacity of your short term memory by combining stimuli into larger possibly higher order units, called chunks: is a group of familiar stimuli red as a single unit.

-According to Allan Baddeley working memory in short-term includes four components:

1) Phonological rehearsal loop: this component is a work when you use recitation.

2) Visuospatial sketchpad: permits people to temporarily hold & manipulate visual images.

3) Executive control system: controls the deployment of attention, switching the focus of attention and dividing attention as needed.

4) Episodic buffer: a temporary, limited-capacity store that allows the various components of working memory to integrate information and that serves as an interface between working memory (stm) & long-term memory.

3: long-term memory: an unlimited capacity store that can hold info for lengthy periods of time. (Minutes to years)

-One point of view is that memory is stored in LTM permanently.

-Wilder Penfield reported triggering long-lost memories through electrical stimulation of the brain (ESB) during brain surgeries; he & other inferred that there were exact playbacks of these memories.

-Flash-bulb memories: unusually vivid and detailed recollections of momentous events. (e.g. some people remember what they were doing, how they felt on Sept. 11, 2001.)

-These lines of research show that LTM storage is not permanent. [Penfield’s work included major distortions or factual impossibilities.] & [Flash-bulb memories are not as accurate because like other memories, with time they become less detailed & complete.]

• How is knowledge represented & organized in the memory?

• Clustering: the tendency to remember similar or related items in groups.

(Factual info is routinely organized into simple groups and when possible, the info is organized into conceptual hierarchies.)

• Conceptual hierarchies: a multilevel classification system based on common properties among items.
• Schema: organized cluster of knowledge about a particular object or event abstracted from previous experience with the object or event. (People are more likely to remember things that are consistent with their schemas than things that are not.) BUT (people sometimes do remember things better that violate their schema based expectations.)
• Semantic network: consists of nodes representing concepts joined together by pathways that link related concepts. (Figure 7.1, a semantic network. P. 297)
• Connectionist, or parallel-distributed (PDP) models: assume that cognitive processes depend on patterns of activation in highly interconnected computational networks that resemble neural networks. (See P. 297)
• Proactive interference: occurs when previously learned info interferes with the retention of new information.
• Repression: refers to keeping distressing thoughts and feeling unconscious.
• Memory tracing

• Long-term potention (LTP): is a long lasting increase in neural excitability at synapses along a specific neural pathway.

• Amnesia; 2 types: Retrograde amnesia involves the loss of memories for events that occurred prior to the onset of amnesia & Anterograde amnesia involves the loss of memories for events that occur after the onset of amnesia.

• Consolidation: is a hypothetical process involving the gradual conversion of information into durable memory codes stored in LTM.

• Systems & types of memory

• Implicit memory: is apparent when retention is exhibited on a task that does not require intentional remembering.

• Explicit memory: which involves intentional recollection of previous experiences.

• Implicit memory in unconscious must be accessed indirectly & can be accessed with variations on relearning (savings) measures of retention. In contrast, explicit memory is conscious, accessed directly and can be accessed with recall or recognition measures of retention.

• Theorists suggest that people have separate memory systems for different kinds of information:

• Declarative memory system: handles factual information

• Non-declarative or procedural memory system: houses memory for actions, skills, operations, and conditioned responses.

• Declarative memory subdivided into episodic & semantic memory: Episodic memory contains personal facts. (Ex/ first kiss) & semantic memory contains general facts. (Ex/ Christmas is on Dec.25th.)

• Episodic memory is like an autobiography while semantic memory is like an encyclopedia.

• Prospective memory: involves remembering to perform actions in the future. (Ex/ remembering to call someone, walk the dog, etc.)

• Retrospective memory: involves remembering events from the past or previously learned information. (Ex/ remembering what your prof said during last lecture class.)