Fig. 1.

The moment-to-moment developmental sequence of free exploration. The developmental landmarks in a specific BALB/c mouse-session performed across a 3-h period. The spiral proceeding from top to bottom, first in the left and then in the right column, presents the time-series of 2-D locations on the path traced by the mouse. The enumerated figure-inserts show the 12 landmark motions described in the text, traced in red within the arena, and on the spiral. Blue dots indicate instances in which the mouse approached the cage doorway and did not enter the cage (cage-skips), or stopped short of returning all of the way home during a return (Home-related-shuttle). Absence of a blue dot implies departure into home-cage. Yellow path stands for the return portion within a Home-related-shuttle.