Ch.5 Short-term memory

what is sensory memory?

• a temporary store that holds incoming sensory information for very brief periods of time

What are the two sensory memories?

1. iconic memory

   • brief sensory memory of things we see

2. echoic memory

   • brief sensory memory of things we hear

Iconic Memory

• capacity is very large but duration is very short

• forms automatically, without attention or interpretation

what is short-term memory?

• retaining information beyond the sensory memories

STM - Chunking

chunking strategies can improve with practice

• its when a set of items become associated with a new unit in memory

STM - Visual Short term memory

• visual short term memory is when you have the ability to store and manipulate visual information

Visual short term memory - Luck & Vogel

• did an experiment using the change detection technique (participants are shown an array of objects for a brief period, then there is a brief delay/break, then they are shown a second array and have to see if anything changed between the first and second)

• Their work found that the capacity for visual stm is about 4 objects or items (colour, shape, orientation)

Duration of STM

• Brown-Peterson Paradigm

• would should participants a set of items, then make them count backwards by 3s; then after the delay they were asked to recall the items

Findings: duration of STM is about 15-20 seconds

Working Memory - what are the 4 components of the Baddeley’s model?

1. Central executive

2. Phonological loop

3. Visuospatial sketch pad

4. Episodic buffer

1. Central Executive

• most important component; acts as the control system

• important for focusing, dividing and switching attention

2. Phonological loop (phonological similarity effect, word length effect)

• verbal and auditory information

Example: repeating a phone number over and over again so you remember it

Similarity effect: memory is worse for items that sound alike than items that sound different

Word length effect: memory for lists of words is better for short words than for long words; this is because it takes longer to rehearse them and produce them during recall

What are the implications?

• can not retain in a loud talk-filled environment

3. Visuospatial sketch pad

• handles visual and spatial

• pointing to Y or N is easier than verbally saying yes or no

4. Episodic buffer

• receives and integrates information from your LTM

• combines information from the phonological loop and the visuospatial sketch pad

• holds information longer and has greater capacity than phonological loop or visuospatial sketch pad

• does not just store but binds information together

Example: if you want to recall a story you heard; (use of visual details and sound) the episodic buffer

Working memory - Cowan’s Model

• working memory is organized into two levels

  1. activated LTM representations

     • information decayed if not rehearsed

  2. focus of attention

     • limit of 4

     • controlled by executive by central executive

  does not believe that LTM is not directly apart of our working memory, but that information from LTM can be brought into focus on attention if needed

Working Memory - Simple span

• the ability to recall a sequence of items

Example: when you are presented with a series of numbers and are asked to repeat them, the longest sequence a person can remember without error is considered their simple span

Working memory - Complex span

• this is where you manipulate information

• individuals with high WMC tend to have higher IQs

what are three types of complex span tasks used to measure capacity?

1. reading span

2. operation span

3. word span

Reading span

• asking participants to read sentences and then making them recall the final word of every sentence

Operation span

• present math equations to participants and ask them if they are correct, then show them a word after each equation

• after multiple, equations, ask participant to recall the words

Word span

• participants are presented with a sequence of words and they have to recite them

• as the words get longer they are more difficult to recite

• the longer a person can recall is there word span

Working Memory - Neural Process

• areas across the frontal and parietal lobe are involved in working memory

• This was discovered by Patricia Goldman

  • experiment with monkeys who did a delayed response task

  • monkeys without a prefrontal cortex had difficulty holding information in WM