encoding
transforming information into a form that can be entered and retained in the memory system.
storage
retaining information in memory so that it can be used at a later time.
retrieval
recovering information stored in memory so that we are consciously aware of it
sensory memory
decays rapidly
- A store of sensory information
- Modality specific (one for each sense):
- Iconic memory for visual information.
- Echoic memory for auditory information.
iconic memory (sperling 1960)
Sperling (1960)
• Letters flashed for 50 milliseconds.
• Write down as many of the letters as possible & how many letters you think were presented
- Brief visual memory.
- Visual counterpart to echoic memory.
- Limited duration.
- Iconic memory decays within 500ms (Sperling, 1960).
iconic memory characteristics
• Appears to decay rapidly
-It seems like we can see a lot, but we can only ever access a bit of that information before the information disappears.
• We can selectively report visual properties
-Such as size, color, brightness or shape.
• But we cannot report category information
-E.g., cannot identify if the items are all number or all vowels, etc.
echoic memory
- Auditory sensory memory.
- Auditory equivalent of iconic memory.
- Both Iconic and Echoic memory have a large capacity.
- …but the information decays rapidly.
- Information decays within a second for iconic information.
- Information decays within a few seconds for echoic information.
millers 7+-2 items/chunks
- Miller suggested that there was a limited capacity for short-term memory/attention and that this was approximately 7 items/chunks.
- However, there are limitations to consider:
- Sizes of chunks may differ depending on the information being encoded
- Capacity may be limited by duration of time, rather than number of items/chunks
- Word length effect (Mueller et al., 2003)
chunking information
- What we encode can be either an individual item or a chunk
- Several number or letters can be encoded together or individually
- Allowing us to remember short sentences or sets of numbers.
are all chunks equal
- The size of the chunks encoded will affect the number of items later recalled
- Jacobs (1887)
- Larger mean memory span for numbers (9.3 numbers) compared to letters (7.3 letters).
- Suggests it is easier to chunk numbers rather than letters….
word length effect
- Mueller et al. (2003).
- Mean memory span greater for word list A (6.7 words) than list B (5.1 words).
- Related to the time taken to pronounce each word.
- Takes longer to pronounce words in list B compared to list A.
how else can we examin STM capcity
- Recency effects
- When recalling words from a list:
- Likely to recall words from the start (encoded in LTM).
- Likely to recall words at the end (words still available in STM).
- Glanzer & Cunitz (1966)
- Delay recall (with distractor task).
- Reduces memory performance for last 2-3 items.
Glanzer and Cunitz (1966)
when participants are delayed in when they can provide their responses, the memory performance is affected for the last few items. As participants are required to perform a distraction task during this time, the last few items cannot be rehearsed, so they cannot be passed to LTM or maintained in STM, so memory performance reduces for those items.
maintenance rehearshal
- Necessary to retain the information in STM.
- Elaborative rehearsal
- Necessary to transfer information from STM to LTM.
levels of processing (Craik & Lockheart, 1972)
- Proposed a number of different levels of processing:
- Shallow / physical:
• Detecting specific letters in words.
• Detecting Fonts/colors etc.
• Detecting sounds (Phonemic processing).
• Deep / semantic:
• Recalling facts.
• Creating sentences.
• Associations.
shallow processing
would involve consider the physical features of a word – eg detecing specific letters in a word.
deep processing
involves considering a word at a semantic level, such as thinking of a suitable adjective for the word, or a synonym (meaning)
working memory model
The working memory model has similar constraints as STM in terms of having a limited capacity. Whilst each component can function independently from the others, they all have a limited capacity. If a person is required to perform two (or more) tasks concurrently that involve the same component of working memory, performance will be negatively affected across the tasks being performed.
- memory operates on information too.
- So, storage plus processing.
- A temporary mental workspace.
the phonological loop
- Can be conceptualised as the Inner ear
- Two components:
- Phonological store
- Concerned with speech perception
- Articulatory control processes
- Concerned with speech production
- Rehearsal
phonological similarity effect
- Recalling words in order was 25% worse with a phonologically similar list, compared to a dissimilar list.
- Suggests speech-based rehearsal processes within the phonological loop.
visuo-spatial skethpad
- Can be conceptualised as the Inner eye.
- Used in the temporary storage and manipulation of spatial and visual information.
- Visual information will travel through this sketchpad.
- Involved in keeping track of where we are in relation to other objects as we move through our environment.
Logie (1995)
argues for two components of visuo-spatial working memory:
• Visual cache = Stores information about visual form and colour.
• Inner scribe
• Processes spatial and movement information.
• Involved in rehearsal of information in visual cache.
• Transfers information from the cache to the central executive.
limited capacity - vogel 2001`
- A display of objects presented to participants.
- A second display of objects presented 900 ms later.
- Participants required to state if the displays are the same.
- Accuracy high for 4-item displays.
- Performance dramatically decreases as the number of items increase.
- Approximately four items (Vogel et al., 2001; Xu & Chun, 2009).
what is central executive
• Drives the whole system (e.g. the boss of working memory) and allocates data to the subsystems (VSS & PL).
• It also deals with cognitive tasks such as mental arithmetic and problem solving.
• The central executive decides what working memory pays attention to.
• Arguably nothing to do with memory per se but more with attention!
Capacity limited
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misc17
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sensation, perception and consciousness29
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attention30
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object and face recognition25
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memory40
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---recalling information from memory---13
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---forgetting---12
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---amnesia---13
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---memory consolidation---9
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---antergrade amnesia---17
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---how can we improve our memory5
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vision35
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language35
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thinking and reasoning33
