Developmental psychology.pdf

Memory 245
Figure 9.10
Decay Theory. According to this
theory, the memory trace, like
skywriting, gradually disappears with
the passage of time.
The case of Benjamin Burtt seems to provide some support, for the boy did
nothing with his knowledge of Greek for years, after which he had still lost much of
it. But this memory loss also might be explained on other bases.
Consolidation Theory
Another view of forgetting that postulates a storage failure focuses upon sudden destruction
of a new trace, presumably in its formative stages, rather than slow deterioration
of a well-established trace simply through disuse. In consolidation theory it is
postulated that the trace needs time to become firmly fixed Certain conditions occurring
soon after an experience can eradicate the memory before it becomes permanent.
From what we have said about the memory trace, it is not surprising that any
event which disrupts normal neural functioning also can disrupt memory. Certain drugs
and excessive anesthesia inhibit neural activity, and they can also result in loss of recent
memories, presumably by interfering with the consolidation of the trace. Electroconvulsive
shock, in contrast, augments neural activity to the point of inducing a mild
convulsion in the psychiatric patient, and it too disrupts memory. Such patients usually
forget the trip to the hospital or clinic and even other events immediately preceding
the treatment (White, 1956).
Time Factor and Physical Shock Various experiments with rats, fish, and other
animals have shown the importance of the time factor in obliteration of the memory
trace. When electroconvulsive shock occurs immediately after learning, forgetting is
the largest. When experimental rats were given electroconvulsive shock at several
different intervals following the original learning, a test of retention 25 hours later
showed that the sooner the shock was administered, the larger was the disruption (Pinel
& Cooper, 1966).
Other studies have demonstrated that memory disruption apparently occurs
by preventing protein synthesis, considered earlier as a possible chemical basis of memory
through RNA. In one experiment goldfish learned to avoid an electric shock by
swimming to the darker end of the tank. Immediately after this learning, some of the
fish were injected with puromycin, a substance that interferes with protein synthesis.