Memory-Types-Theories of Memory

What is Memory?
Memory is a faculty of mind by which information is encoded, stored and retrieved. Memory is vital to experience related to limbic systems; it is the retention of information over time for the purpose of influencing future action
Memory is a power of retaining and recalling past experiences. We can also say that the cognitive processes whereby past experience is remembered.

■Memory is better for material if we are able to meaningfully interpret that material.

■Prefrontal regions of the brain are associated with meaningful pro- cessing of events, whereas posterior regions, such as the temporal cor- tex, are associated with representing categorical information.

■After processing a linguistic message, people usually remember just its meaning and not its exact wording.

Types of Memory
1) Sensory Memory
 Sensory memory can only stores information for brief second. It is further divided into two parts

Visual sensory memory—brief memory of an image or icon. Also called iconic memory. 

■When people see a picture, they attend to and remember best those aspects that they consider meaningful.

Auditory sensory memory—brief memory of a sound or echo. Also called echoic memory.  Auditory sensory memories may last a bit longer than visual sensory memories
 2) Short-term memory 
Short-term memory can hold information longer, but it is only usually about 30-40 seconds.
3) Long Term Memory
Long-term memory, however, can last a lifetime. Long-term memory is further divided into two parts:
I. Explicit memory—memory with awareness; information can be consciously recollected; also called declarative memory. There are two types of Explicit memory 

Episodic memory: Memory tied to your own personal experiences 

Semantic Memory: Memory not tied to personal events. General facts and definitions about the world
 II. Implicit memory—memory without awareness; memory that affects behavior but cannot consciously be recalled; also called non-declarative memory 

Procedural Memory: Memory that enables you to perform specific learned skills or habitual responses

                   Theories of Memory
Multi-Store Model
 An influential theory of memory known as the multi-store model was proposed by Richard Atkinson and Richard Shiffrin in 1968. This model suggested that information exists in one of 3 states of memory: the sensory, short-term and long-term stores. Information passes from one stage to the next the more we rehearse it in our minds, but can fade away if we do not pay enough attention to it (Atkinson & Shiffrin, 1968)

Levels of Processing 
Fergus Craik and Robert Lockhart were critical of explanation for memory provided by the multi-store model, so in 1972 they proposed an alternative explanation known as the levels of processing effect. According to this model, memories do not reside in 3 stores; instead, the strength of a memory trace depends upon the quality of processing, or rehearsal, of a stimulus.
In other words, the more we think about something, the more long-lasting the memory we have of it (Craik & Lockhart, 1972)

 Working Memory Model
Alan Baddeley and Graham Hitch viewed the short-term memory (STM) store as being over-simplistic and proposed a working memory model which replace the STM. The working memory model proposed 2 components - a visuo-spatial sketchpad (the ‘inner eye’) and an articulatory-phonological loop (the ‘inner ear’), which focus on a different types of sensory information. Both work independently of one another, but are regulated by a central executive, which collects and processes information from the other components similarly to how a computer processor handles data held separately on a hard disk (Baddeley & Hitch, 1974)

Miller’s Magic Number
 Prior to the working memory model, U.S. cognitive psychologist George A. Miller (1956) questioned the limits of the short-term memory’s capacity. In a renowned 1956 paper published in the journal Psychological Review, Miller cited the results of previous memory experiments, concluding that people tend only to be able to hold, on average, 7 chunks of information (plus or minus two) in the short-term memory before needing to further process them for longer storage. For instance, most people would be able to remember a 7-digit phone number but would struggle to remember a 10-digit number. This led to Miller describing the number 7 +/- 2 as a “magical” number in our understanding of memory (Peterson & Peterson, 1959)

Flashbulb Memories
 Psychologists Roger Brown and James Kulik recognized this memory phenomenon as early as 1977, when they published a paper describing flashbulb memories - vivid and highly detailed snapshots created often (but not necessarily) at times of shock or trauma (Brown & Kulik, 1977)

Memory and Smell
 Researchers at the University of North Carolina tested the olfactory effects on memory encoding and retrieval in a 1989 experiment. The results showed that participants were better able to recall memories when the scent at the time of encoding matched that at the time of recall. These findings suggest that a link between our sense of smell and memories remains, even if it provides less of a survival advantage than it did for our more primitive ancestors (Cann and Ross, 1989).

Interference
 Interference theory postulates that we forget memories due to other memories interfering with our recall. Interference can be either retroactive or proactive: new information can interfere with older memories (retroactive interference), whilst information we already know can affect our ability to memorize new information (proactive interference).

 False memories
 Coan (1997) demonstrated that false memories can even be produced of entire events. He produced booklets detailing various childhood events and gave them to family members to read. The booklet given to his brother contained a false account of him being lost in a shopping mall, being found by an older man and then finding his family. When asked to recall the events, Coan’s brother believed the lost in a mall story to have actually occurred, and even embellished the account with his own details.

The Weapon Effect on Eyewitness Testimonies
A person’s ability to memorize an event inevitably depends not just on rehearsal but also on the attention paid to it at the time it occurred. In a situation such as an bank robbery, you may have other things on your mind besides memorizing the appearance of the perpetrator. But witness’s ability to produce a testimony can sometimes be affected by whether or not a gun was involved in a crime. This phenomenon is known as the weapon effect (Johnson & Scott, 1976)