They seem duller when young.

Boys often get credit for dulness compared with girls on this account.

Even as early as the second year can this distinction among children be readily observed in many instances.

The motor child will show sorrow by loud crying and vigorous action, while the sensory child will grieve in quiet, and continue to grieve when the other has forgotten the disagreeable occurrence altogether.

The motor one it is that asks a great many questions and seems to learn little from the answers; while the sensory one learns simply from hearing the questions of the other and the answers given to them.