> 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/calibration-phases.md).

# Calibration phases

Calibration phases collect baseline EEG data before, during, or after stimuli phases. 

We recommend keeping calibration phases in your experiments, particularly if you intend to use performance metrics in your analysis.

When you add a calibration phase to your experiment, it automatically includes:

* a 15-second eyes open and eyes closed condition,
* a default instructions screen,
* a countdown, and 
* a fixation cross. 

You can also edit a calibration phase to:

* change the duration of the eyes open or eyes closed condition, and 
* disable the eyes open or eyes closed condition. 

*You cannot add new elements to a calibration phase; this is so calibration phases can be analyzed together and treated the same in your data download.*

![](https://lh5.googleusercontent.com/qmJnU0qSJCLHf6-NORf3xc248x2RF5eixdW9kx4V2QfJWDab_xZGznNS2hc-NHy_kOjgxQJHf1-jBF30xlmGnr5TcLVb-bIlLPfsLD61TRu2if_CvTLlbo30s_Bzi6d6_bTTB1yY=s0)

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