are placed in a circular pool about the size of a child’s swimming pool, filled
with water that has been made opaque. Around the outside of the pool, objects
such as doors, windows, and curtains are arranged as landmarks. A small platform
is placed in the pool, just below the opaque water’s surface, which makes it invisible.
While the rat swims around the pool trying to find this platform to rest on, a
video camera records its path (represented by the lines in these figures). After
the first few tries, normal rats are able to swim directly to the platform on
(B) In contrast, when the experiment
is conducted with rats whose spatial memory has been impaired by lesions in their
hippocampus, their path indicates an inability to remember where the platform
is, even after many trials.
Schenk and Morris, 1985.)