Illustration with a clock and four sets of eyes, progressing from fully open to mostly closed. (IMAGE)

Iowa State University

Illustration with a clock and four sets of eyes, progressing from fully open to mostly closed.

Caption

Illustration with a clock and four sets of eyes, progressing from fully open to mostly closed.

Credit

Deb Berger/Iowa State University.

Usage Restrictions

Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted.

License

CC BY-NC-ND

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