blink-cursor-alist is a variable defined in `C source code'.
Its value is

Alist specifying how to blink the cursor off.
Each element has the form (ON-STATE . OFF-STATE). Whenever the
`cursor-type' frame-parameter or variable equals ON-STATE,
comparing using `equal', Emacs uses OFF-STATE to specify
how to blink it off. ON-STATE and OFF-STATE are values for
the `cursor-type' frame parameter.

If a frame's ON-STATE has no entry in this list,
the frame's other specifications determine how to blink the cursor off.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.