uality_ is an advantage, quite apart from the matter of
intensity. Saturated colors, though no stronger in intensity of light
than pale colors, are stronger stimuli for attention. High notes are
more striking than low. Itch, tickle and pain get attention in
preference to smooth touch. "Striking" cannot be defined in physical
terms, but simply refers to the fact that some kinds of stimulus get
attention better than others.

_Definite form_ has the advantage over what is vague. A small, sharply
defined object, that stands out from its background, attracts the eye
more than a broad, indefinite expanse of light such as the sky. In the
realm of sound, "form" is represented by rhythm or tune, and by other
definite sequences of sound, such as occur in the jingles that catch
the little child's ear.

The factors of advantage so far mentioned are native, and a stimulus
possessing one or more of them is a natural attention-stimulus. But
the individual also learns what is worth noticing, and what is not,
and thus forms _habits of attention_, as well as habits of
inattention. The automobile driver forms the habit of attending to the
sound of his motor, the botanist forms the habit of noticing such
inconspicuous objects as the lichens on the tree trunks. On the other
hand, any one forms the habit of not noticing repeated stimuli that
have no importance for him. Move into a house next the railroad, and
at first you notice every train that passes; even at night you awake
with a start, dreaming that some monster is pursuing you; but after a
few days the trains disturb you very little, night or day. The general
rule covering attention habits is this: anything that you have to work
with, or like to play with, acquires the power to attract your
attention, while anything that you do nothing {248} with loses
whatever hold on your attention it may have possessed by virtue of its
intensity, quality, etc.

Besides these permanent habits of attention, there are temporary
adjustments determined by the _momentary interest_ or desire. Stimuli
relevant to the momentary interest have an unwonted hold upon
attention, while things out of line with this interest may escape
attention altogether, even though the same things would ordinarily be
noticed. What you shall notice in the store window is governed by what
you are looking for as much as by the prominence of the object in the
total display. When you are angry with a person, you notice bad points