Idiot Savant

Idiot Savant is a perk in Fallout 4.

Effects
For ranks 1 and 2, the perk randomly activates whenever you gain experience from any source. At 1 Intelligence, the chance of activation is 10%, and you lose 1% per added point of Intelligence. The chance minimizes at 0.5% at Intelligence 11 or higher.

When the perk activates, you will see a laughing Vault-Boy above the compass, and hear a laughing sound. The experience you would have earned will instead be boosted to 3x (for rank 1) or 5x (for rank 2+). This boost is multiplicative with any normally additive experience bonuses from being well-rested or having a high Intelligence.

The probability for the "kill bonus" from rank 3 is independent of the bonus experience from rank 1 and 2 and the probability of it triggering is nearly the same, except it is 1% at 11 Intelligence or higher.

Comparison to Intelligence

 * $$AvgExpMulti = 1 + \Bigg(\frac{min(2,IdiotSavantLevel) \times %Chance}{50}\Bigg) $$


 * $$OverallExp = IntMulti \times AvgIdiotSavantExpMulti$$

When comparing a perk point to put into higher Intelligence or Idiot Savant, it is worth comparing the returns you get. Each point in Intelligence improves experience gain by 3%. Consulting the above table, it can be seen that with this perk, average experience gain actually drops when increasing Intelligence until very high levels of Intelligence.

Bugs

 * Having an Intelligence of 0 or lower will completely stop Idiot Savant from working.
 * If the Idiot Savant perk procs (activates) when turning in the radiant quest Learning Curve, you will sometimes not get the 3x or 5x multiple of experience points.

Behind the scenes
The term idiot savant refers to an individual who is overall mentally disabled but nonetheless displays an exceptionally high level of ability in performing a specific task such as memory, arithmetic, art, or music.

Савант