Cortex vault

The cortex vault was an additional electronic brain which was possessed by bronze Daleks such as Rusty. It contained memory banks and monitoring the Dalek's thoughts. One of its functions was to keep a dalek "pure". To stoke the fire of the a Daleks hatred whilst simultaneously extinguish even the smallest glimmer of compassion, Mercy or Kindness. The Doctor Saw this as possibly one of the most evil creations in the Universe describing it as "Evil Refined as engineering"   (TV: Into the Daleks)