Its effects aren’t fully explained in-game, but it affects a couple of Earthbound’s mechanics:
IQ governs a character’s PP (Psychic Points) pool. The higher the IQ the higher the PP. IQ determines the success rate of Brainshock. Jeff’s IQ determines what broken items he is able to repair.
A common misconception is that IQ influences PSI ability damage. This is untrue though, as PSI abilities do fixed damage.
How Does IQ Affect PP?
Simply put, the more IQ a party member has, the higher their PP is. The formula is very simple too – every point of IQ equates to 5 PP. Out of all the four main characters, Jeff ends up with the highest IQ stat at level 99. His PP pool permanently stays at 0 however, as he is unable to use PSI abilities. Paula’s is the next highest, but actually does serve her well. She ends up learning a ton of useful PSI abilities, and this will be her primary mode of damage dealing. Ness is fairly down the middle when it comes to IQ. Although he ends up having less IQ than Paula, this doesn’t really stunt him in any way, as his PP pool still ends up being decently sized. Plus, after the Magicant segment of the game, his IQ stat as well as his other stats will gain a permanent increase. Poo suffers from a small PP pool, which is unfortunate as he also heavily relies on PSI abilities as his primary source of damage. I recommend giving him a helping hand with IQ capsules. Check out our Earthbound Capsule guide to find out more!
Effects on Brainshock Success Rate
When Brainshock is used, it has a chance to inflict the “feeling strange” effect on its target. This basically functions like standard RPG confusion, making affected targets sometimes hit other targets with their attacks. The success rate of this comes down to whether the user has more IQ than the target. If the target has a higher IQ, the effect will be unsuccessful. Poo is the only party member that can learn Brainshock, while it can also be used by a handful of enemies. Interestingly you can use Brainshock on Giygas as he is susceptible. This makes the final encounter much, much easier.
Fixing Broken Items with Jeff
As stated earlier, Jeff ends up with a monster IQ stat as he levels up. Although he is unable to use PSI abilities, he has a special use for his IQ stat. During the course of your playthrough, you will likely come across broken items. These are useless on their own, but if Jeff has a high enough IQ, he will fix it after spending a night in a hotel or bed. The IQ requirement for each broken item is a fixed amount, and if Jeff’s IQ is the same or higher, he will fix it no matter what. We’ve included a handy table to show what broken items you can find, the IQ needed, and what they become when fixed.
