This chapter explores the phenomenon of memory, defining it as the persistence of learning
over time through the encoding, storage, and retrieval of information and skills 1, 2. It begins by
outlining three measures of retention: recall (retrieving information like a fill-in-the-blank task),
recognition (identifying learned items like multiple choice), and relearning (the increased
speed of learning material a second time) 1, 3. The sources then detail the Atkinson-Shiffrin
model, which describes memory formation in three stages—sensory memory, short-term
memory, and long-term memory—while highlighting contemporary modifications such as
working memory (active processing of information) and automatic processing (information
bypassing conscious tracks) 4, 5.
The chapter emphasizes the brain's dual-track processing system:
●​ Explicit (Declarative) Memories: These consist of facts and experiences we
consciously know and require effortful processing 6, 7. They are facilitated by the
hippocampus (encoding/storage) and frontal lobes (retrieval/executive functions) 8, 9.
●​ Implicit (Nondeclarative) Memories: These are formed via automatic processing
without our awareness, covering procedural skills (like riding a bike), conditioned
associations, and information about space, time, and frequency 7, 10. These are stored
in the cerebellum (conditioned responses) and basal ganglia (motor skills) 8, 9.
Key concepts regarding memory encoding and capacity include:
●​ Sensory Memory: A very brief recording of sensations, such as echoic memory
(auditory, lasting 3-4 seconds) and iconic memory (visual, lasting 1/20th of a second)
10, 11.
●​ Short-Term/Working Memory Capacity: We can typically hold 7 +/- 2 bits of
information, which decays rapidly within 12 to 18 seconds without active rehearsal 12,
13.
●​ Effortful Processing Strategies: Retention is improved through chunking (organizing
data into manageable units), mnemonics (memory tricks using imagery or peg-words),
and hierarchies 14-16. Furthermore, deep (semantic) processing—focusing on the
meaning of information—and the self-reference effect make encoding far more
effective than shallow processing of sounds or appearances 17, 18.
●​ Distributed Practice: The spacing effect shows that study sessions spread over time
lead to better long-term retention than massed practice (cramming), especially when
combined with the testing effect (answering questions rather than just rereading) 19.
The biological basis of memory involves:
●​ Neural Networks: Memories are not stored in isolated files but in overlapping neural
networks that rewire and interconnect as learning occurs 20.
●​ Long-Term Potentiation (LTP): This is the process where synapses become more
efficient at sending signals through repetition and structural changes 3, 21.
●​ The Role of Emotion: Intense emotions trigger stress hormones that activate the
amygdala, which "tags" memories as important, leading to vivid—though not always
accurate—flashbulb memories 21, 22.
Finally, the chapter addresses retrieval challenges and influences:
●​ Retrieval Cues: Memories are stored in a web of associations (conceptual, contextual,
and emotional) 23.
●​ Priming: This "invisible memory" occurs when the unconscious activation of
associations influences our current thoughts or interpretations 24.
●​ Context and State Dependence: We recall information better in the same physical
environment (context-dependent) or emotional state (mood-congruent memory) in
which it was learned 25, 26.
●​ Serial Position Effect: This is the tendency to best remember the first items (primacy
effect) and the last items (recency effect) in a list .
●​ Infantile Amnesia: Most people have a memory "blank" before age three because the
hippocampus is late to develop and the adult mind relies on verbal narratives that
preverbal infants do not possess 27.