Appletons' Popular Science Monthly, May, 1900: Vol. 57, May, 1900 to October, 1900Various
Science
Appletons' Popular Science Monthly, May, 1900: Vol. 57, May, 1900 to October, 1900
Various
Science -- Periodicals; Technology -- Periodicals
=“Winking.”=--No satisfactory determination has been made of the reason
we wink. Some suppose that the descent and return of the lid over the
eye serves to sweep or wash it off; others that covering of the eye
gives it a rest from the labor of vision, if only for an inappreciable
instant. This view borrows some force from the fact that the record
of winking is considerably used by experimental physiologists to
help measure the fatigue which the eye suffers. In another line of
investigation Herr S. Garten has attempted to measure the length of
time occupied by the different phases of a wink. He used a specially
arranged photographic apparatus, and affixed a piece of white paper
to the edge of the eyelid for a mark. He found that the lid descends
quickly, and rests a little at the bottom of its movement, after which
it rises, but more slowly than it fell. The mean duration of the
downward movement was from seventy-five to ninety-one thousandths of
a second; the rest with the eye shut lasted variously, the shortest
durations being fifteen hundredths of a second with one subject and
seventeen hundredths with another; and the third phase of the wink,
the rising of the lid, took seventeen hundredths of a second more,
making the entire duration of the wink about forty hundredths, or four
tenths of a second. The interruption is not long enough to interfere
with distinct vision. M.V. Henri says, in _L’Année Psychologique_, that
different persons wink differently--some often, others rarely; some
in groups of ten or so at a time, when they rest a while; and others
regularly, once only at a time. The movement is modified by the degree
of attention. Periods of close interest, when we wink hardly at all,
may be followed by a speedy making up for lost time by rapid winking
when the tension is relieved.
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