Figure 2.
Michotte's (1963) caterpillar stimulus. The square appears to move itself by first rhythmically expanding from the right edge, then contracting from the left edge.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.