WHAT IS MEMORY?
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possible. It gives point to the theory which explains the laying down of memory images in terms of changes in the protein structure of the cell. This objection to the possibility of the brain's accommodating all the impressions a person receives takes into account the time he spends asleep. Then presumably he receives no stimulation from the outside world, although even this view has now been seriously questioned. Recent research has also discovered two kinds of storage: temporary (short-term) and permanent (long-term). During temporary storage an impression is liable to be erased, although even when in permanent storage, it can still be temporarily forgotten. After about an hour, the memory is either erased or transferred to permanent storage. It is the latter which involves changes in the amount and composition of the protein molecules in the brain cells. Studies suggest, in fact, that shortterm memory is electrical, long-term is chemical. The chemical view of the nature of memory is, however, on less firm ground than the electrical. McConnell gave flatworms an electric shock preceded by a bright light. Having learned to respond to the light in anticipation of the shock, they were then ground up and fed to other flatworms. McConnell found that the second group responded to the light without having been trained to do so. He argued that the memory of the learning experience was transferred chemically from one set of worms to the other.3 The validity of McConnelTs finding is uncertain because other researchers have been unable to repeat his experiment. They found it impossible to condition the worms or to obtain transfer of the 'memory' in the way that McConnell claimed. The academic world remained sceptical of the result and, as Barry Singer remarks in Science and the Paranormal, circulated jokes about grinding up older professors and feeding them to younger ones. The electrical activity of the brain may play a part in the retrieval of memories. 'Brainwaves', as this activity is commonly known, are poorly organized in early infancy, and this may explain why we can recall virtually nothing from that period of life. At present it is impossible to decide among the above views. It may even be that all three are true and that there are memories of three types: those laid down in a particular area of the brain, those existing as patterns of electrical stimulation, and those represented by protein activity. If, throughout this book, we continue to refer to memory traces, we do so