A large sample of a normal population were studied by a group of psychiatrists for the effects of parental bereavements: 21 percent of the sample were found to have lost a parent in childhood. In considering the type of memory of the event retained by the adult, the age of nine was shown to be crucial. When the death was experienced at or below the age of nine, grief was recalled only in rare cases. Grief of the surviving parent might be recalled, but only from the age of nine and upwards was one's own grief likely to be remembered (Hilgard, et al.). C. W. Wahl suggests why the memory is repressed. Frustration of the developing child by the parent is met by "a reversal wish of the frustrating act," in which the parent would be banished. "Early in his life these wishes become equated with 'death wishes' towards frustrating objects." But at the infantile stage of thinking, such thoughts are felt both as effective and as invoking a similar punishment on the self, given the appropriate circumstances: the Law of Talion. Hence if a parent is lost by death or separation, this is perceived by the child as proof

that his thoughts have magical power which can kill and destroy. The individual, therefore, lives in expectation that the same Talion punishment will be visited upon him by a malignant or wrathful divinity or fate. In addition, the child conceives of parental death or separation as a deliberate abandonment of him by the absent parents, a hostile act on their part for which he is, again, responsible, and for which he will have to pay. . . . Causation is personified and the child feels guilt subsequent to a death, as though he were the secret slayer. (Wahl)

The years from six to nine are the most dangerous for bereavement. Prior to six, as Maria Nagy showed, children lack any realistic concept of death. Death is assimilated to sleep or rebirth, and death elicits puzzlement or, at worst, separation anxiety. The death concept only emerges, according to Sylvia Anthony, after "the child's powers of effective action have greatly reduced the tendency to efficacy-thinking" (that is, infantile omnipotence of thought). But from six to nine, with a primitive concept of death, anxiety at bereavement arises "on a basis of regression, which itself is a normal temporary reaction to experiences demanding personal readjustment, such as the death of a member of the family" (Anthony; cf. Bowlby).