> For the complete documentation index, see [llms.txt](https://emotiv.gitbook.io/emotivpro-builder/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://emotiv.gitbook.io/emotivpro-builder/building-an-experiment-in-builder/intervals.md).

# Intervals

Intervals or interstimulus intervals allow you to:

* add a customizable interval image from your computer’s files or image library, such as a fixation cross or blank screen; and
* edit the interval duration or make the interval duration random (between a certain range)

To set an interval for a stimuli phase, click on the **Settings** button, then select Intervals.

![](https://lh4.googleusercontent.com/h-t7jesWYalTYsQUaPLTSx1CaRo_pQ1UGa6eI2ycKP7PmecShbEnxNAzzpJsGKnurWllLWZ0crHJ6nTfF5o1ZDbDslicP4TaMtaEN30w-xllmpkpepZ640RTIX-n_EZA0Mp05X5A=s0)