How memory works
The Modal model was proposed by Richard Atkinson and Rihcard Shiffrin in 1968. Variations of this models are collectively known as information processing models.
Sensory memory refers to initial perceptual processing that identifies incoming stimuli. Information that has been processed in sensory memory is then passed to short-term memory, where it receives additional meaning-based processing. Information that is relevant to one's goals is then stored indefinitely in long-term memory until it is needed again.
Short-term memory refers to the place where information is processed for meaning. Like sensory memory, short-term memory is limited with respect to capacity and duration. Many researchers now prefer the name working memory, which reflects the active processing of information. See Baddeley's (1986, 2001, 2007) model of working memory below.
Sensory memory refers to initial perceptual processing that identifies incoming stimuli. Information that has been processed in sensory memory is then passed to short-term memory, where it receives additional meaning-based processing. Information that is relevant to one's goals is then stored indefinitely in long-term memory until it is needed again.
Short-term memory refers to the place where information is processed for meaning. Like sensory memory, short-term memory is limited with respect to capacity and duration. Many researchers now prefer the name working memory, which reflects the active processing of information. See Baddeley's (1986, 2001, 2007) model of working memory below.
Working memory
Central executive is assumed to be a limited capacity control system that governs what enters short-term memory. Another function is selecting strategies necessary to process information. The central executive also controls two slave systems: the visuospatial sketchpad and phonological or articulatory loop. The former enables us to hold visual-spatial information in short-term memory and perform various computations on that information. The latter enables us to hold acoustic information temporarily via rehearsal, usually 2-4 seconds. In 2000 Baddeley added a fourth component to the model, the episodic buffer. This component is a third slave system, dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information with time sequencing (or chronological ordering), such as the memory of a story or a movie scene. The episodic buffer is also assumed to have links to long-term memory and semantic meaning.
Long-term memory involves memory traces developed over periods of time. It is the permanent repository of the lifetime of information we have accumulated. The most important for LTM are meaning and organization. Recall depends on our understanding what information means and being able to access it.
More on Atkinson-Shiffrin modal model here.
Central executive is assumed to be a limited capacity control system that governs what enters short-term memory. Another function is selecting strategies necessary to process information. The central executive also controls two slave systems: the visuospatial sketchpad and phonological or articulatory loop. The former enables us to hold visual-spatial information in short-term memory and perform various computations on that information. The latter enables us to hold acoustic information temporarily via rehearsal, usually 2-4 seconds. In 2000 Baddeley added a fourth component to the model, the episodic buffer. This component is a third slave system, dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information with time sequencing (or chronological ordering), such as the memory of a story or a movie scene. The episodic buffer is also assumed to have links to long-term memory and semantic meaning.
Long-term memory involves memory traces developed over periods of time. It is the permanent repository of the lifetime of information we have accumulated. The most important for LTM are meaning and organization. Recall depends on our understanding what information means and being able to access it.
More on Atkinson-Shiffrin modal model here.
ENcoding and retrieval
Encoding - placing information into long-term memory. This stage of memory formation along with retrieval is crucial in understanding fallibility of eyewitness testimony.
Encoding specificity - a principle that states that remembering knowledge is enhanced when conditions at retrieval match those present at encoding. In other words, not only the way we encode information matters, but also the environment in which the learning process occurs should match the environment in which retrieval takes place. (Tulving & Osler, 1968) For example, when a conversation was heard in a stressful situation, one will remember more details when asked to recall the conversation in similar conditions. This phenomenon is referred to as state-dependent learning. In one study (1981), Gordon H. Bower found that students who learned information when they were sad recalled that information better when they were in a similar emotional state. In 1975 David Godden and Alan Baddeley found similar differences when individuals learned information on land or under water. (referenced in Bruning, Schraw, & Norby, 2011)
This phenomenon has important implications for conducting investigations and questioning subjects. One suggestion would be to ask individuals recall certain events at the location where those events have happened.
Encoding specificity - a principle that states that remembering knowledge is enhanced when conditions at retrieval match those present at encoding. In other words, not only the way we encode information matters, but also the environment in which the learning process occurs should match the environment in which retrieval takes place. (Tulving & Osler, 1968) For example, when a conversation was heard in a stressful situation, one will remember more details when asked to recall the conversation in similar conditions. This phenomenon is referred to as state-dependent learning. In one study (1981), Gordon H. Bower found that students who learned information when they were sad recalled that information better when they were in a similar emotional state. In 1975 David Godden and Alan Baddeley found similar differences when individuals learned information on land or under water. (referenced in Bruning, Schraw, & Norby, 2011)
This phenomenon has important implications for conducting investigations and questioning subjects. One suggestion would be to ask individuals recall certain events at the location where those events have happened.
(Re)constructive memory
Retrieval - accessing the information from memory. Retrieval is reconstructive memory (Craik, 2002; Greene, 1992), just as encoding is constructive memory. Only key elements are usually stored in long-term memory. When we encode them, we are guided by schemata - mental frameworks we acquire through experience. At retrieval, we bring up the key elements and put them together filling out the gaps to reconstruct what we encountered. This process allows us to process far less information than if we encoded and retrieved all of the information we encountered. Sometimes when we perceive events through personal experience we give off our guesses as actual information. For instance, when several individuals are asked to give account of a traffic accident, they all will produce different perspectives, one of which might be a pure guess of the person who did not witness an accident, but made a judgement after seeing the consequences of it.
You can find one of the illustrations of reconstructive memory in an experiment first conducted by Frederick Bartlett in 1932, on review page.
You can find one of the illustrations of reconstructive memory in an experiment first conducted by Frederick Bartlett in 1932, on review page.
Now that you know that memories even of highly memorable events are not as precise as we think and that information can be stored in sensory memory for no more than 4-5 seconds, you will hopefully be more careful handing eyewitness testimony or when giving your own account of certain events. The video below gives you one example of problems with eyewitness testimony.
Scott Fraser is a forensic psychologist who thinks deeply about the fallibility of human memory and encourages a more scientific approach to trial evidence. To read his profile on TED click here.