When a user clicks a widget, such as a button, to invoke a widget behavior in a web page, an overlay module may delay the invoking of the widget behavior while executing a stimulatory effect. The stimulatory effect may be a visual effect, such as a gradual fill of the button, that stimulates the user to provide a re-click. A re-click can cause the stimulatory effect to conclude and to invoke the widget behavior. The re-click event, based on human impatience, may be determined to be an indicator of a human user.