THE FUNCTION OF MEMORY 



homes, much less the wayside configurations in a trip of a hundred miles. 

 Yet we see the former daily, and the latter may be accomplished a second 

 time without the aic] of a map. "Mental states of every kind — sensations, 

 feelings, ideas — which were at one time present in consciousness and then 

 have disappeared from it, have not with their disappearance absolutely 

 ceased to exist. Although the inwardly-turned look may no longer be able 

 to find them, nevertheless they have not been utterly destroyed and an 

 nulled, but in a certain manner they continue to exist, stored up, so to speak, 

 in the memory" (Ebbinghaus, 1913). 



I believe that these analogies with human experiences make for a better 

 understanding of memory in waterfowl. We speak here not of the recollec- 

 tive memory, but of the subconscious retentiveness which "is the basal fact 

 of life. All growth and development in an organism depends upon con- 

 tinuity. . . . The events of a life story would form no story, could have no 

 continuity, one with another, unless at every moment the past lived into the 

 present. But such continuity does not necessarily involve knowledge of 

 the past. ... In retentivenes, the past is continued into the present and 

 loses itself in making the present what it is" (Gulliksen, 1950). By some 

 process we do not understand, visual experiences become part of an or- 

 ganism, so that the sum total of its being is not only flesh and blood, bone 

 and nerve, but includes the memory traces of parts of the world that have 

 been seen and experienced and that always exist within. 



The duckling has memory of its mother and distinguishes her from all 

 other females. You and I standing beside the pond cannot distinguish each 

 female of a kind with constant surety, yet the duckling still wearing the 

 egg-tooth directs its activities toward the one hen that is its parent. This 

 holds even when the mother returns after separation from her family. Hein- 

 roth (1911) showed that this recognition of the mother was not inborn; 

 the young are not innately attracted to their genetic parent. Young geese, 

 Heinroth observed, may become attached to the human caretaker who first 

 handled them, accepting this man as their parent. Ducklings hatched under 

 a domestic chicken recognize her as their mother. Thenceforward this 

 chicken to which they directed their first actions remains their mother, 

 even though they may be brought into association with females of their 

 own species; and they recognize their gallinaceous parent from all other 

 chickens. Lorenz (1935, 1937) called this mother-recognition "imprinting," 

 pointing out that the young do not recognize their mother instinctively, 

 but must be conditioned to her. "Parents and young thus appear to inherit 



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