Models of Memory

Models of Memory

1. Multi-store model - (Atkinson & Shiffrin, 1968)

   • Sensory stores
     • The visual store (iconic memory) holds visual information very briefly. Sperling (1960) argued that information in iconic memory decays within about 500 milliseconds
     • It has been assumed that memory is preattentive, as it doesn’t depend on attention – Atkinson and Shiffrin (1968) – attention occurs after information has been held in the sensory stores
     • The auditory store (echoic memory) holds auditory information for a few seconds. Research has found that the duration of echoic memory is longer in the left hemisphere, which probably reflects the dominance of the left hemisphere in language processing
   • Short term memory
     • Very limited capacity – digit span – participants asked to repeat a random series of digits back immediately after hearing them – the maximum number of correct items recalled is 7 plus or minus 2 items (Miller, 1956)
     • However, we must distinguish between items and chunks, which are groups of items that have been collected together and treated as a single unit. Chen and Cowan (2009) presented participants with previously learned chunks. Only 3 chunks were recalled in the absence of rehearsal
     • Information can be lost from STM – either by decay in the absence of rehearsal or by interference.
   • Evaluation
     • Strengths
       • It is still widely accepted today and has had a great influence on memory research
       • There is lots of experimental evidence which provides strong support for the distinction between STM and LTM
     • Weaknesses
       • The model is oversimplified – it assumes that the short term and long term stores are both unitary
       • It assumes the short term store acts as a gateway between the sensory stores and LTM. This is incorrect because the information processed n STM has already made contact with information in LTM (Logie, 1999)
       • It assumes that most information is transferred to LTM via rehearsal, which greatly exaggerates the role of rehearsal

2. Working memory model - (Baddeley & Hitch, 1974)

   • Phonological loop
     • Consists of a phonological store, which is concerned with speech perception, and an articulatory process, which is linked to speech production
     • The phonological similarity effect - reduced recall when words are phonologically similar - Larsen et al (2000) found that the ability to recall the words in order was 25% worse with the phonologically similar list
     • The word length effect - word span is greater for short than long words - Research Baddeley (1975) suggests that the effect depends on rehearsal
     • Evidence from brain damaged patients indicates the existence of a phonological store and an articulatory process located in different brain regions
   • Visuo-spatial sketchpad
     • Used for the temporary storage and manipulation of visual information and spatial movement
     • Logie (1995) argued that it consists of 2 components; the inner scribe, which stores information about form and colour, and the inner scribe, which stores spatial and movement information
     • However, other studies have indicated that different brain regions are activated when carrying out a visual and spatial task, which suggests they are separate systems
   • Central executive
     • A central allocating system, which is the most important component in working memory
     • It is assumed that the prefrontal cortex is the brain area most involved in the functions of the central executive; however, patients with damage to the prefrontal cortex don't always show executive deficits
     • Miyake et al (2000) identified 3 executive processes: inhibition, shifting and updating and discovered they were positively correlated with each other
   • Episodic buffer
     • Information from the other stores can be stored briefly
     • The original 3 components were too separate from each other. The episodic buffer helps to integrate information within working memory
   • Evaluation
     • Strengths
       • It is concerned with both processing and storage of information, and so it is involved in all complex cognitive tasks
       • It incorporates verbal rehearsal as an optional process, which is more realistic than the enormous significance of rehearsal in the multi-store model
     • Weaknesses
       • It have proved difficult to identify the nature of the main executive processes associated with the central executive
       • We need more research on the relationship between the episodic buffer and other components of working memory