Intelligence/Fallout: New Vegas

Intelligence is one of seven primary statistics in the SPECIAL system

Gameplay
The number of skill points gained each level is based on the formula 10 + (0.5 * IN) per level, including level 1, where IN is the Courier's Intelligence. If one gets a non-whole number of skill points per level (e.g. 10.5 for INT 1) it will be saved for the next even level up (see Skill Rate).

Increase

 * Permanent
 * Intelligence Implant available at the New Vegas medical clinic (+1)
 * Intense Training perk (+1 per rank)
 * Completing the quest The Apocalypse or The End will allow raising any one primary statistic by 1.
 * Temporary
 * Only permanent increases in Intelligence will increase points received when leveling up. While traits are relatively permanent (they cannot be changed at any time like the other temporary items), they will not increase level-up points.
 * Armor and clothing
 * Mad scientist scrubs, Scientist scrubs, Dr. Klein's glasses (+1)
 * Dr. Klein's scrubs, Dr. Mobius' scrubs, Dr. Mobius' glasses (+2)
 * Chems
 * Mentats (+2)
 * Party Time Mentats (+2)
 * Perks
 * Meat of Champions (+1 for 60 seconds after eating a corpse.)
 * Night Person (+2 between 6:00 PM and 6:00 AM)
 * Traits
 * Claustrophobia (+1 while outdoors, but -1 indoors)
 * Early Bird (+2 between 6am and 12pm, but -1 between 6pm and 6am)
 * Black coffee (+2 - +6 depending on Survival skill)
 * "Smart Light" (+2 for 12 hours or until the player character uses the "Mood Lights")

Decrease

 * Temporary
 * Armor and clothing
 * Lobotomite goggles, Lobotomite mask and goggles (-2)
 * Consumables
 * Alcohol (effects do not stack)
 * Absinthe, beer, Battle Brew, Jake Juice, Rum & Nuka, scotch, vodka, whiskey, wine (-1 to -3 depending on Survival skill)
 * Irradiated beer, irradiated scotch, irradiated whiskey (-1 to -3 depending on Survival skill)
 * Moonshine (-2)
 * Wasteland tequila (-2 to -6 depending on Survival skill)
 * Large wasteland tequila (-3 to -9 depending on Survival skill)
 * Chems
 * Ant nectar (-2)
 * Ant queen pheromones, Fire ant nectar (-3)

Low Intelligence
In addition to alternative Intelligence checks, low Intelligence changes some dialogue options when speaking to vendors and non-player characters. For example, when speaking to Miguel at Miguel's Pawn Shop, the option to start trading is "Me buy things," and when speaking with Dr. Usanagi at the New Vegas medical clinic after she gives the Courier the initial description about implants they get the dialogue option "You sell plants, too?", which will cause her to re-explain the implants and suggest [the player character] take the implant to make them smarter. If taking her up on this deal, she will state that she thinks the Courier "could really benefit from it," and offer the implant at a discount.

In place of the gibberish of past games, however, the player character will simply not completely understand a conversation, confuse what someone is saying with something else entirely, or not understand what situation they are currently in. In the REPCONN Headquarters, for example, a character with an IN of < 3 can bypass a robot that demands a password by saying "ICE CREAM!" Normally, a Luck of at least 7 would be needed to guess this.

Low-Intelligence characters attempting to do the quest That Lucky Old Sun will be granted several unique dialogue options when conversing with Fantastic and Ignacio Rivas. An example is when informed about the hostilities between the Followers and the NCR, the Courier can ask, "Do Flowers and NCR bear play together?"

When first speaking to Ranger Milo he will inform the Courier that some "Legion snakes" are held up in Nelson, to which they can respond "Snakes are small. Why don't you just use a gun or whatever to shoot them." He will then call them a "special folk," and explain that they are not really snakes but "like snakes."

While helping Argyll in Nellis medical station while doing the quest Volare!, the Courier is given an option to "CHOP CHOP CHOP!" instead of giving him treatment. Ironically, the Courier actually saves the patient and Argyll comments on it, saying it was "dumb luck."

In Dead Money, the Courier will say "bye-bye, light person!" upon exiting dialogue with a hologram. If the Courier's Intelligence stat is the most extreme (highest or lowest), Doc Mitchell will either compliment saying "maybe them bullets done your brain some good" (for highest) or apologize, stating he fixed up the Courier's head the best he could (for lowest).

Intelligence 3
An Intelligence of 3 or less will grant "special" reverse-Intelligence dialogue and actions. The majority of instances are listed below.


 * When contacted via Ham radio, Tabitha will identify a player with Intelligence of 4 or higher as an interloper and attack, but mistake a player with intelligence 3 or lower for a "dumb dumb"
 * During Come Fly With Me, one has the unique option to randomly mash the buttons on the launch control panel. The rockets will take off and rewards will be gained as though one passed the 55 Science check to properly input improved coordinates.
 * When convincing Arcade Gannon to become a companion, one can do so out of pure sympathy, in place of a Speech 70 check, by saying that Freeside is very complicated and a smart guy like him could help do stuff.

Intelligence 2
An Intelligence of 2 or less will grant an "extra special" reverse-Intelligence dialogue
 * When approached by the mobile facial recognition scanners on the third floor of REPCONN Headquarters, one can inadvertently guess the security password and roam the area without acquiring a keycard.