Performance pixels are a visual representation of your performance during a study session. 

To turn on Performance Pixels, pause any study session and click the toggle:

Performance pixels appear on the bottom left of your screen:

There are four types of pixels:

• Green pixels indicate that you remembered a review word. Good job!
• Red pixels indicate you forgot a review word. You'll see these words again in the same study session, and when you are able to remember them three times in a row, they will receive a green circle around them. Nice!
• Purple pixels indicate that you checked a word that was assumed known.
• Blue pixels indicate you learned a new word. Beautiful!