Successive tests pf the same memory often appear to change it. Either by consolodation of a correct response. Or an increased probability of repeating errors. This raises the question as to whether the act of attempted recall modifies existing memory traces or creates new ones. Experimental work in this area is complicated by difficulties (a) in isolating what the interations between successive trials actually reflect, and (b) determining exactly when such interactions have taken place. A methodology is described in which the difficulties can be overcome within the domain of a specific experimental paradigmZ: the repeated cueing (RTTT) method used by Jones (1974). Analysis provides three significant findings. Firstly. attempts at recall produce an engram which is normally unavailable after a small number of cases these traces may survive for at least the duration of the experiment. Finally. analysis of subject's confidence ratings indicates that subkects are able to distinguish between recalls of stimuli and previous answers implying an addition to. rather than a corruption of exisitng memory.