• Memory – processes that allow us to record and later retrieve experiences and information

Memory as Information Processing

  • Encoding – getting information into the system by translating into a neural code that your brain processes
  • Storage – retaining information over time
  • Retrieval – the process of accessing information in long term memory

Three-Component Model

  • Three major components of memory:
    • Sensory memory – holds incoming sensory information just long enough for it to be recognized
      • Composed of sensory registers:
        • Iconic store (visual sensory)
        • Echoic store (auditory sensory) – lasts longer than iconic
    • Short-Term/Working memory – type of memory that holds the information that we are conscious of at any given time
      • Working memory refers to fact that it consciously processes, codes, and works on information
      • Mental representations are how information is coded to be retained in short term memory
        • When reading words, information is stored as phonological codes
      • Short term memory can only hold limited information
        • Most people can hold no more than five to nine meaningful items
        • Chunking – combining individual items into larger units of meaning
        • Maintenance rehearsal – simple repetition of information
        • Elaborative rehearsal – involves focusing on the meaning of information or relating it to other things we already know
      • Three components of working memory (according to Alan Baddeley):
        • Auditory working memory – repetition of information to self
        • Visual spatial working memory – temporary storage and manipulation of images and spatial information
        • Central executive – decides how much attention to allocate to mental imagery and auditory rehearsal
    • Long-Term memory – vast library of more durable stored memories
      • Serial position effect – recall of information is influenced by a word’s position in a series of items
        • When given a long list of words, the beginning and ending words are most remembered
          • Primacy effect – superior recall of early words
            • At first, brain rehearses beginning words, storing into long term memory
            • List gets longer, and short term memory fills up
          • Recency effect – superior recall of recent words
            • Last words remembered since they aren’t bumped out of short term memory by newer words

Encoding: Entering Information

  • Effortful processing – encoding that is initiated intentionally and requires conscious attention
  • Automatic processing – encoding that occurs without intention and requires minimal attention

Levels of Processing

  • Structural encoding – processing based on structure of information
  • Phonological encoding – processing based on sound
  • Semantic encoding – processing based on meaning
  • Levels of processing concept: the more deeply we process information, the better it is remembered
    • Semantic encoding involves most processing, since meaning must be focused on
    • Reason why elaborative rehearsal is more effective than maintenance rehearsal

Organization and Imagery

  • Hierarchies and chunking
    • Takes advantage of principle that memory is enhanced by associations between concepts
    • Chunking widens information processing caused by limited capacity of short term memory (e.g. encoding phone number in sets of numbers)
  • Mnemonic devices
    • Mnemonic device is any type of memory aid (including hierarchies and chunking)
    • Does not reduce amount of information to encode, but provides extra cues to retrieve information
  • Visual imagery
    • Dual coding theory – encoding information using both codes (verbal and nonverbal) enhances memory
      • Odds improve that at least one of the codes will be available
  • Schema – an organized pattern of thought about some aspect of the world
    • Create a perpetual set

Storage: Retaining Information

Memory as a Network

  • Associative network – a massive network of associated ideas and concepts
    • Priming – activation of one concept by another (e.g. “fire engine” primes the node for “red”)
  • Neural network – each concept is represented by a particular pattern or set of nodes that becomes activated simultaneously

Types of Long-Term Memory

  • Declarative and Procedural memory
    • Declarative – involves factual knowledge, broken into two subcategories:
      • Episodic memory – store of factual knowledge concerning personal experience
      • Semantic memory – general factual knowledge about the world and language, including words and concepts
    • Procedural – memory reflected in skills and actions
      • One component consists of skills involved in “doing things” in particular situations
      • Other component reflects classical conditioning effects
  • Explicit and Implicit memory
    • Explicit – involves conscious or intentional memory retrieval
    • Implicit – occurs when memory influences our behaviour without conscious awareness (e.g. riding a bike, driving)

Retrieval: Accessing Information

  • Retrieval cue – any stimulus (internal or external) that stimulates the activation of information stored in long-term memory
    • Multiple self-generated cues is most effective way to maximize recall
  • Flashbulb memories – recollections that seem so vivid and clear, that they can be pictured as if they were a snapshot of a moment of time
    • Accuracy of these memories fades over time

Context, State, and Mood Effects on Memory

  • Encoding specificity principle – memory is enhanced when conditions present during retrieval match those that were present during encoding
  • Context dependent memory – phenomenon that it is typically easier to remember something in the same environment in which it was acquired
  • State dependent memory – ability to retrieve information is greater when our internal state at the time of retrieval matches the original state during learning
    • Does not extend to mood states
      • Mood congruent recall – tendency to recall information or events that are congruent with our current mood

Forgetting

  • Forgetting tends to occur more rapidly at first, then slows down
    • Most of forgotten information occurs right away, then only a little forgotten over rest of time

Why Do We Forget

  • Encoding failure – information was never encoded into long term memory
  • Decay theory – proposes that with time and disuse, the physical memory trace in the nervous system fades
    • Problem in prediction that longer intervals of disuse cause increased decay of information
      • Reminiscence – phenomenon where more material is recalled during second testing of information than the first
  • Two types of interference:
    • Proactive interference – occurs when material learned in the past interferes with recall of new material (e.g. learning a new phone number)
    • Retroactive interference – occurs when newly acquired information interferes with the ability to recall earlier acquired information (e.g. recalling an old phone number)
    • Tip of the tongue phenomenon does not always reflect a retrieval of information problem (sometimes the answer is never known to begin with)
  • Motivated forgetting – motivational processes (e.g. repression) may protect us by blocking the recall of anxiety-arousing memories

Amnesia

  • Retrograde amnesia – memory loss for events that occurred prior to the onset of amnesia
  • Anterograde amnesia – memory loss for events that occur after the initial onset of amnesia
  • Infantile amnesia – memory loss for events that occurred during the first few years of our lives
    • Experienced by everyone

Forgetting to do Things

  • Prospective memory – concerns remembering to perform an activity in the future
    • People with better retrospective memory don’t have better prospective memory

The Misinformation Effect and Eyewitness Testimony

  • Misinformation effect – distortion of a memory by misleading post-event information
  • Source confusion – tendency to recall something or recognize it as familiar, but to forget where it was encountered

The Biology of Memories

Where in the Brain are Memories Formed?

  • Hippocampus and Cerebral Cortex
    • Hippocampus and adjacent tissue help encode and retrieve long term declarative memories
    • Cortex encodes by processing information from sensory registers
    • Memory consolidation – creation and binding together of neural codes that allow information to be transferred from short term memory into long term memory
      • Consolidation in hippocampus allows for many components to become a unified memory
  • Thalamus and Amygdala
    • Damage to thalamus can produce amnesia
    • Amygdala encodes emotionally arousing and disturbing aspects of events
      • Damage can disrupt conditioned fear response
  • Cerebellum
    • Plays an important role in the formation of procedural memories

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