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Memory Introduction

Memory is a complex and varied phenomenon.  Ideas about what constitutes memory and how it works can be traced back to ancient times.  Plato compared memory to an aviary, and in some respects his ideas have remained little changed into the modern era. 

Plato likened human memory to an aviary with memories (birds) flying around inside.  A new bird can be captured and added to the aviary (placing a new memory into storage), and at a later date the bird can be captured in a net and removed (retrieval of a memory). Inability to capture a bird or its escape from the cage are useful analogies for the two basic processes of forgetting.

Some modern theories of memory still use this principle of storage and retrieval, however it is becoming more popular now to see memory as a process rather than simply a storage system.  Research in recent years has shown that far from being a perfect recording of an event our memories do change over time and can be influenced by others and by later events. 

The notes that follow are meant to provide a thorough overview of the topic as it is described by the AQA Specification.  They should be regarded as a bare minimum and consequently should be supplemented by class notes and independent notes following your own extensive background reading! 

An evolutionary perspective

We take memory for granted and cannot imagine a life that had no past experience to give the present some kind of context.  Animal memory is quite different to our own despite human memory almost certainly evolving from the ability of lower species to recall certain events. 

For animals memory is about food (finding it or finding where they’ve cached it), mates (where to find them) and predators (where to avoid them).  Some species have evolved what we would consider to be amazing memories. 

Squirrels and many bird species like the black-capped chickadee and Clark’s nutcracker, can recall the sites of dozens, in some cases thousands of sites where food has been cached for the winter.  Pigeons can remember routes back to their nests from hundreds of different locations using landmarks and possibly smells. 

However, other species also forget.  For example the chickadee will forget where it has hidden food usually within 28 days.  Forgetting therefore seems to be of evolutionary advantage.  Cached food will presumably be either rotten or discovered by somebody else if not eaten within that time.  Remembering past this ‘sell by date’ would therefore be a pointless activity.  Perhaps human forgetting was once something to be blessed rather than cursed. 

The multistore model:

Background

The multistore memory (Atkinson and Dhiffrin 1968) suggests memory has two main components; STM and LTM.  In addition it also has a set of sensory stores where images, sounds, smells etc. appear to reverberate around still at the sensory locations momentarily.  The model will be discussed in more detail a little later, but to make more sense of the model we will first consider the two main stores, their feeders (the sensory stores) and the differing properties of STM and LTM.

Sensory Memory

Sensory memory acts as a filter with each sense having its own brief ‘storage system.’  Throughout the day and to some extent even when we are asleep, our senses are bombarded with information.  So as you’re sat reading this there will be other visual stimuli around you, there will also be noises, smells etc.  Few if any of these will be remembered.  When you walk into town or to school you will pass dozens of cars, but unless they are in some way unusual you will recall no detail about them.  The sensory memory appears to hold information for a fraction of a second.  If we decide that the information is not important it disappears and will not be recalled later.  Only if it is important (particularly if it is threatening), unusual or meaningful will we pay attention to it and transfer it to STM.  Sensory memory therefore plays a vital role in filtering out the vast majority of useless stuff that impinges on our senses and enables us to focus our attention on important detail.

Sperling (1960) presented participants with grids of 12 letters arranged in three rows.  Each grid was displayed by a tachistoscope, designed to present the letters for 50 milliseconds. 

So in a follow up Sperling played a tone straight after the letters had disappeared.  A high tone signalled that the top row should be recalled, a low tone the bottom and a mid tone the middle row.  Sperling found that even though the words had been removed before the tone sounded, there was still sufficient time for the participants to be able to ‘glance back’ through their visual store and recall an average of three of the letters from the appropriate row. He concluded that participants could therefore hold about 9 or 10 items in their visual sensory (iconic) store.

Some children have an eidetic memory allowing them to store information in the short term sensory store for much longer than the half second or so most of us can manage.  Haber & Haber (1964) gave such children a picture from Alice in Wonderland that they were allowed to study for 30 seconds before it was replaced by a blank sheet.  They were then asked questions about minor details in the picture.  Their eyes would scan corresponding areas of the blank sheet as they recalled, in the present tense, with considerable accuracy details of the picture that had long since disappeared from view. 

The human echoic store (sensory store for hearing) is particularly useful.  Without it conversation would be difficult since it holds words for a few seconds allowing us to recall what was said at the start of a sentence as well as at the end. 

Imagine yourself vegetating in front of “I’m a celebrity chef with a delinquent nanny get me an interview in the House with Alan Sugar.”  You can feel yourself slipping into a lowered state of consciousness as rigor mortis of the brain sets in!  Your mum asks you what’s on the other side and you look round, temporarily roused from slumber and say “What?”  As you do so you’re able to rewind the question in your mind and it occurs to you that you did hear what he said after all!  This would be your sensory store for sound in practice; the sounds were still reverberating in your ear! 

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