Memory: Storing & Accessing Information

• 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