Memory
Maintaining information over time / the mental processes of acquiring and retaining information for later retrieval
• Explicit memory – recollect of learning event,
environmental / physical, declarative, depth of processing during encoding influences level of performance, level of performance no affected by perceptual characteristics, amnesia is descrived as explicit memory deficit
• Implicit memory – no reference to initial encoding episode, procedural, insensitive to level of encoding, sensitive to physical characteristics of stimuli, classical amnesia does not affect implicit memory
However not a measure of cognitive theory, in studies of amnesia procedural and declarative definitions more meaningful
Models of memory –
4 models, serial models (Atkinson-shiffrin model, Levels of
processing model and Tulvig’s model) and a parallel model (parallel distributed processing model). Serial models are most useful to explain amnesia
Atkinson Shiffrin model of memory
sensory memory – iconic and echoic, if paid attention to send to STM
STM – 7 +/- 2 items, if not encoded it is forgotten LTM – memories change and develop via rehersal
The movement of info through stages depends on the amount of attention paid to it
Levels of processing Craik and lockhart
Information is retained according to the level of processing it has undergone.
Shallow vs deep processing – shallow is weak, deep are more durable
Maintenance (repetition, less likely to be encoded) vs elaborative rehersal (associating with existing semantic knowledge, more durable)
Tulvig’s model of memory
same as Atkinson-shiffrin model but LTM in more detail Long term memory split into -
Parallel distributed processing
Memory is activation of connections in different areas simultaneously.
The pattern of activation is memory / knowledge
The strength of the connections between relevant sites is changed in learning
*Not the nodes, it’s the pattern of the nodes and how they connect eg must stand then walk then run, strengthen these connections Long term Memory systems
• Procedural memory – storage of skills and procedures, motor performance. Supported by memory systems outside the hippocampal system
• Declarative memory – accumulation of facts and data from learning experiences, system is outcome of processing by various processing systems which feed the hippocampal system activation of declarative memory causes activation of related memories, memory activation can be
independent of environment
• Episodic memory – knowledge of an event, re experiencing autobiographical events or projecting experiences into the future. This is developed later than other memory systems.
Shares neural mechanisms / cognitive processes with other memory systems, but also has its own mechanisms.
• Semantic memory – knowledge of facts / common knowledge without the “re experiencing” of an event.
Semantic – Episodic Dissociation –
Squire and Zola say that at the level of cognition semantic and episodic memory are completely independent. declarative memory is dependent on the hippocampus. Damage results in impairments to both episodic and semantic memories indicates they operate in parallel. For example, amnesic patient have equal difficulties with event and factual memory.
Tulvig’s Serial Parallel Independent Hypothesis - argues episodic memory is an extension if the semantic
system. encoding episodic memory relies on the semantic system, but the semantic system does not rely on the episodic. Retrieval however is completely independent.
Damage to the semantic system will also damage encoding of the episodic memory system. Damage to the episodic system however will not
effect the encoding of the semantic system. But in recall, damage to one will not effect the other.
à Vargha-Khadem et al. studied patients who had suffered bilateral medial temporal lobe injury (hippocampi). The patients all had abnormally small bilareral hippocampi, but relatively intact extra hippocampal temporal lobes. All of the cases had severe memory impairment but normal intellectual capacity (ie acquired extensive semantic information).
This study concludes that the systems must be functionally
dissociable since one can function without the other, plus episodic memory relies on the hippocampal circuit. The findings match Tulvigs model (episodic damaged but semantic intact)
