Memory: the ability to store and retrieve information over time.
The three key function of memory: encoding, storage and retrieval.
- Encoding: the process by which we transform what we perceive, think, or feel into an enduring
- Storage: the process of maintaining information in memory over time.
- Retrieval: the process of bringing to mind information that has been previously encoded and
- Three types of encoding processes: elaborative encoding, visual imagery encoding, and organizational
- Semantic judgements: requires the participant to think about the meaning of the words.
- Rhyme judgments: requires the participant to think about the sound of the words.
Visual judgements: requires the participant to think about the appearance of the words.
- Elaborative encoding: the process of actively relating new information to knowledge that is
already in memory.
- Visual imagery encoding: the process of storing new information by converting it into mental
- Organizational encoding: the process of categorizing information according to the relationship
among a series of items.
Three major kinds of memory storage: sensory, short-term, and long-term.
- Sensory memory: holds sensory information for a few seconds or less.
o Ionic memory: a fast-decaying store of visual information. (Decay in about a second or
o Echoic memory: a fast-decaying store of auditory information. (Decay in about fives
- Short-term memory: holds nonsensory information for more than a few seconds but less than a
minute. Can hold information for about 15 to 20 seconds.
o Rehearsal: the process of keeping information in short-term memory by mentally
repeating it. (Each time you repeat the number you are “reentering” it into short-term
memory giving it another 15 to 20 seconds of shelf life)
o Able to hold onto seven meaningful items but old information will be lost if new
information is added to the list.
Chunking: combining small pieces of information into larger clusters or chunks.
o Working memory: active maintenance of information in short-term storage.
Includes subsystems that store and manipulate visual images or verbal
information as well as central executive that coordinate the subsystems.
- Long-term memory: holds information for hours, days, weeks, or years.
o The hippocampal region of the brain is critical for putting new information into long-
term store. It is the “index” that links together all of the sights, sounds, smells and
o Anterograde amnesia: the inability to transfer new information from the short-term
store into the long-term store.
o Retrograde amnesia: the inability to retrieve information that was acquired before a
particular date, usually the date of an injury or operation.
o Consolidation: a process by which memories become stable in the brain. o Reconsolidation: memories can again become vulnerable to disruption when they are
recalled, thus requiring them to be consolidated again.
- Memories are in the spaces between neurons (the synapses).
- Sending a neurotransmitter across a synapse changes the synapse. It strengthens the connection
between the two neurons making it easier for them to transmit to each other the next time.
- “Cells that fire together wire together”
- Long-term potentiation: commonly known as LTP, a process whereby communication across the
synapse between neurons strengthens the connection, making further communication easier.
o Occurs in several pathways within the hippocampus, it can be induced rapidly and can
last for a long time.
- NMDA (N-methyl-D-aspartate) receptor: influences the flow of information between neurons by
controlling the initiation of LTP in most hippocampal pathways.
1. The hippocampus contains an abundance of NMDA receptors, more so than in other
areas of the brain.
2. Two things must happen at roughly the same time in order to activate these NMDA
3. First, the presynaptic (sending) neuron releases a neurotransmitter called glutamate (a
major excitatory neurotransmitter in the brain) which attaches to the NMDA receptor
4. Second, excitation takes place in the postsynaptic neuron.
5. Together, these two events initiate LPT which in turn i