Introduction to memory

memory

A set of storage systems and processes for encoding, storing, and retrieving information acquired through our senses and for relating it to previously acquired knowledge and experience = mental representation of knowledge stored within neural networks

Three Stores of Memory

Sensory memory, short-term memory (working memory), and long-term memory.

Encoding

The processes involved in attending to and acquiring information from experiences and mental processes = creates a representational form for storage

Storage

Encoded representations are consolidated in memory traces and stored in networks of neurons throughout the brain

• e.g. neurons in amygdala store info about emotions experienced

Retrieval

reconstructive (sometimes error-prone) process that changes memory traces through reconsolidation after retrieval = remembering. can be explicit or implicit. highly context-dependent as depends on the right environmental or internal cues

Sensory Memory

A temporary, sensory-based representation of input received through sensory channels = only some info stored will be retained. includes iconic (visual) and echoic (auditory) memory = brief duration and large capacity

Iconic Memory

Visual sensory memory.

Echoic Memory

Auditory sensory memory.

George Sperling (1960)

Used full-report vs. partial report methods to determine the capacity and duration of iconic memory.

Full-report Method

On computer - first look at a central fixation cross then cross replaced by square of 12 uppercase consonant letters (3 rows of 4 letters) shown for 50 ms and then asked to name the letters they saw

Partial-report Method

Used similar method to full but tone used as cue for which row to recall (didn’t know which row beforehand)

• high tone = top line

• mid tone = second line

• low tone = bottom line

auditory not visual as removes competition

Multi-store model

Atkinson and Shiffrin (1968) proposed a model of memory that includes sensory memory, short-term memory, and long-term memory. Stores are distinguished based on duration (how long) and capacity (how much)

how memories are created in MSM

stimulus causes initial registration of info in sensory registers - info given attention moves into STM and parts not are lost. Rehearsal in STM stops info from being lost and sufficient rehearsal encodes it into LTM. Retrieval moves info from LTM to STM

full report results

avg. 4/12 and reported feeling able to briefly access full image but faded too quickly to read all letters = limited capacity and quick decay of memory. Sperling thought this method underestimated true capacity of ionic trace so then used partial report method

partial method results

larger estimate of iconic memory capacity as majority could recall all letters from from any cued row = all 12 items were available = full report underestimated capacity as task exceeded duration of iconic trace

duration of iconic memory

Sperling modified partial to estimate duration by varying the retention interval between stimulus and cue = performance reduced to one item after approx 500 ms (half a second)