Recency and Primacy Effects

The order in which information is learned determines how reliably it will be recalled. The first item in a list is initially distinguished from previous activities as important (primacy effect) and may be transferred to long-term memory by the time of recall. Items at the end of the list are still in short-term memory (recency effect) at the time of recall.

http://brainu.org/recency-and-primacy-effects

Research

Miller and Campbell recorded proceedings from a trial with a combination of sequences of arguments for and against the plaintiff, sometimes with delays of a week between parts and the judgment that they sought from experimental participants.

The results in the table below show that when there was no delay between the first and second message, but then a week’s delay before the judgment, a primacy effect occurred. When there was a delay between the first and second message, but no gap between the second message and the judgment, then a recency effect occurred.

 

First message

Delay after first message?

Second message

Delay after second message?

Judgment

For plaintiff

No

Against plaintiff

No

Balanced

Against plaintiff

No

For plaintiff

No

Balanced

For plaintiff

No

Against plaintiff

Yes

For

Against plaintiff

No

For plaintiff

Yes

Against

For plaintiff

Yes

Against plaintiff

No

Against

Against plaintiff

Yes

For plaintiff

No

For

For plaintiff

Yes

Against plaintiff

Yes

Balanced

Against plaintiff

Yes

For plaintiff

Yes

Balanced

 

http://changingminds.org/explanations/theories/recency_effect.htm

 

According to duration of memory retention, we can classify this faculty into three types:

  1. Short-term Memory: This type of memory allows one to recall a few items (3-5) in a short time, from several seconds to as long as 1 minute. An interesting fact about short-term memory is that information is better recalled if it’s organized in chunks. For example, it’s easier to put in short-term memory the sequence 415-353-525, than it’s to remember 415353525. Therefore, we could benefit enormously if we approach memorization by organizing the information into chunks.
  2. Long-term Memory: Unlike short-term memory, rehearsal is often required for long-term memory. By means of this type of memory, we can store much larger quantities of information for potentially unlimited duration. However, the motto “use it or lose it” applies here nicely. Things that impact us tend to enter long-term memory without excessive barriers. But other, mere facts must be reinforced through repetition. This type of memory stores facts like memories of childhood, for example.
  3. Sensory Memory: It’s the memory that allows one to retain impressions of sensory information after the original stimulus has faded. It’s a very short lived memory, and is outside of conscious control.

 

Physiology of Memory – How do neurons create memories?

It is done by elec­tro­chem­i­cal impulses stream­ing into the brain. Brain con­tains some 100 bil­lion nerve cells called neu­rons which branch out to form over one quadrillion con­nec­tions called synapses.

The eas­i­est way to con­cep­tu­al­ize this is that there are more synapses in the human brain than there are stars in the known uni­verse. Mem­ory and learn­ing occur when the neu­rons and synapses reor­ga­nize and strengthen them­selves through repeated usage. Like building a bridge brick by brick. First there was walking path over fallen tree that 1-2 people were using. With each time they walked over the fallen tree they mounted one extension to it. In time that path grew to the size of the 3m wide bridge allowing more people to walk on it. More people means more building bricks so bridge get stronger and wider. After time it grew to bridge over which thousands of cars are passing over on 4 lanes each way motorway. So from 2 people at one time to thousands both ways at the time. But for some reason I prefer different example from old-time movies where innocent prisoners are trying to escape from prison by digging underground tunnel with a spoon. Carrying the soil in their socks and throwing it away on walking area. Spon by spoon. Eventually after years they can manage to dig a tunnel capable of fitting 1 person at the time allowing then to cross outside the prison walls. Now if you could imagine this process in fast forward e.g. 1 000 000 times you could see only little sparkles as glows of energy flowing during the movements.

How do connections between neurons become strengthened, so that the connection is ‘remembered’? Scientists know that if they give an electrical impulse to a pair of neurons, the two will communicate more easily in the future. This process is known as long-term potentiation (LTP). The effect can last for weeks, or even months – long enough to make a memory. LTP is especially obvious in the hippocampus, one of the areas of the brain active in memory.

Physiologically, memory is related to activity of several brain areas, such as hippocampus, the striatum, and the amygdala, for example. Nevertheless, it’s believed that memory and its counterpart, learning, are linked to changes in neuronal synapses. Neurons are electrically excitable cells in the nervous system that process and transmit information. The brain is a highly complex, nonlinear and parallel information processing system. It has the capability of organizing neurons so as to perform certain computations (e.g., pattern recognition, perception, and motor control.) Neurons are the structural constituents of the brain, massively interconnected between them, forming an enormously efficient and resilient structure.


The brain is constantly restructuring the stored information. In this sense, one of the primary functions of sleep is improving consolidation of such information.

http://life.halcode.com/archives/2008/04/27/stronger-memory-bigger-world/

 

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