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)

Intelligence 5
An Intelligence of 5 is required to understand that Christine can slow the detonation time of your explosive collar near radios when first nearing the vicinity of one, alluding to her companion perk, Signal Interference.

Intelligence 6

 * An Intelligence of 6 is required to convince Joe Cobb of the benefits in taking over Goodsprings and to let the player join his gang in attacking the town, starting Run Goodsprings Run.
 * An Intelligence of 6 is required to see through this traveling merchant's facade and force him into admitting that he is a bounty hunter in disguise during I Fought the Law.
 * An Intelligence of 6 is required to offer the more convincing argument that snipers usually work in pairs when Craig Boone asks why he should join the player after completing One for My Baby.
 * Boone can still be recruited as a companion through another standard dialogue option regardless though.
 * An intelligence of 6 is required to ask how Arcade Gannon how he knows about REPCONN, Poseidon Energy and the Q-35 matter modulator
 * This dialog line is mis-coded such that the check is made against Arcade's 10 intelligence.
 * An intelligence of 6 is required to ask Arcade if he might be holding a grudge against the NCR.
 * An intelligence of 6 is required to ask Emily Ortal how she passed the credit check to enter The Strip
 * An Intelligence of 6 is required to explain that one understands the Brotherhood of Steel is only hostile to those who use plasma or laser weaponry around them, when questioned by Veronica about how much they know about the group.
 * An Intelligence of 6 is required to ask Orris how he managed to kill 4 thugs with 3 shots during the G.I. Blues quest.
 * An Intelligence of 6 is required to cook the imitation strange meat pie using the recipe during Beyond the Beef.
 * An Intelligence of 6 is required to catch Frank Weathers out in his story, and make him admit to running away whilst the rest of his family was captured by Legion slavers.
 * An Intelligence of 6 is required to ask Ranger Milo if he has the authority to order troops into Nelson.
 * An Intelligence of 6 is required to point out to Lieutenant Romanowski there must be a connection between the sudden appearance of crop farms in Westside and the recent shorage of water from NCR pipelines during The White Wash, the point seems lost on him though.
 * An Intelligence of 6 is required to correctly accuse, and subsequently have Tom Anderson admit to, stealing water from NCR pipelines, without having to catch his accomplice in the act during The White Wash.
 * An Intelligence of 6 is needed to ask Arcade Gannon how he knows so much about REPCONN when entering their pre-war headquarters. Passing the check will gain 1 of 5 minimum "history points" with Arcade for him to later initiate For Auld Lang Syne.
 * An Intelligence of 6 is required to understand that Christine has a way to make counterfeit Sierra Madre chips, and subsequently be taught the technique oneself, therefore gaining the Coin Operator perk.
 * An Intelligence of 6 is required to understand why Christine has been ordered to man the Puesta del Sol switching station during Trigger the Gala Event, as Dog/God and Dean Domino lack the technical knowledge to do so
 * An Intelligence of 6 is required to confirm that Dean Domino is giving stage directions to the unlocked door in the Tampico theater.
 * An Intelligence of 6 is required to confirm with Dog that dismemberment and disintegration will stop Ghost people.
 * An Intelligence of 6 is required, upon meeting ED-E (Lonesome Road), to comment on the advanced systems that must be in Hopeville missile silo bunker remote scan and build copies of ED-E
 * An Intelligence of 6 is needed for Doctor Klein to reveal that the plan to save themselves is not yet complete.

Intelligence 7

 * An Intelligence of 7 is required for one to counter Cass' wit by asking if she even knows what a fish is herself after she talks about them.
 * An Intelligence of 7 or a Speech of 70 allows the Courier to talk Alice Hostetler down from killing her mother in the quest Someone to Watch Over Me.
 * An Intelligence of 7 is required to deduce Sergeant Bitter-Root is not being truthful about what he remembers from the Bitter Springs Massacre, to which he will indirectly admit that he may have taken the opportunity to kill some of his own fellow Great Khans during the fighting.
 * An Intelligence of 7 is required to impress Loyal, by presuming that he has planned out a diversionary strategy for the NCR whilst the crashed B-29 is being recovered during Volare!
 * An Intelligence of 7 is required to recite an override command to the mobile facial recognition scanners on the third floor of REPCONN Headquarters, allowing one to roam the area without acquiring a keycard.
 * The response "4f 76 65 72 72 69 64 65 20 33 32" is the hex bytes that correspond to the ASCII character string "Override 32"
 * An Intelligence of 7 is required to convince First Sergeant Astor that Private Edwards is not showing signs of becoming a feral ghoul and allow him to return to the NCR milliary.
 * An Intelligence of 7 is required to explain oneself to Arcade after killing Anderson during The White Wash. Passing the check and choosing the dialogue option which suggests Anderson's death will prevent his thieving from being blamed on the other Westside residents and will gain 1 of 5 minimum "history points" with Arcade for him to later initiate For Auld Lang Syne.
 * An Intelligence of 7 is required to convince Arcade that diverting HELIOS One's power equally across the whole New Vegas grid would be the best choice when he confronts the player after first talking to Fantastic during That Lucky Old Sun. Passing the check will gain 1 of 5 minimum "history points" with Arcade for him to later initiate For Auld Lang Syne.
 * An Intelligence of 7 is required to tell Keller that they are carrying medical supplies for Camp McCarran from Crimson Caravan.
 * An Intelligence of 7 is required to identify that Carlitos worked as a Croupier for Gomorrah.
 * An Intelligence of 7 is required to trick Jacklyn into revealing the necklace Tomas supposedly stole was not actually hers.
 * An Intelligence of 7 is required to suggest that Christine could use writing to communicate when first meeting her in Find Collar 12: Christine, though she will inform the player that is not possible.
 * An Intelligence of 7 is required to impress Christine by understanding her miming a Brotherhood of Steel symbol when first meeting her in Find Collar 12: Christine.
 * An Intelligence of 7 is required to understand the electrical diagram during Fires in the Sky and, when God confronts the player and attempts to blackmail them into keeping him as the active personality, one can call his bluff and suggest that Dog could be shown how to complete the task. This avoids the additional task of collecting ghost harvester remains to satiate his hunger.
 * An Intelligence of 7 is required to complete What's in a Name? for Dr. 0.
 * A subsequent Intelligence of 9 check is required to resolve O's name issue fully. Passing both checks will cause O to side with the player against Dr. Klein during Old World Blues, and act as 1 of the 3 required votes to make peace with the Think Tank if one tries to appeal to their humanity.
 * An Intelligence of 7 is required to recognize the common theme of looping for the Think Tank members' names
 * An Intelligence of 7 is required to note that Doctor Borous' namesake would be the Ouro-borus instead of Ouro-borous.
 * An Intelligence of 7 is required to identify Doctor Borous' broadcasts to the Think Tank as their inspiration to seek out the technologies needed to restore your organs.
 * An Intelligence of 7 is required to recognize the language spoken by the Dead Horse tribal when you arrive in Angel Cave.
 * An Intelligence of 7 is required to identify Ulysses' name as a historic, rather than mythic, name.

Intelligence 8

 * An Intelligence of 8 is required to convince Arcade that he should not be so judgmental of Caesar's Legion because he does not know what they may have gone through. Passing the check will will gain 2 of 5 minimum "history points" with Arcade for him to later initiate For Auld Lang Syne.
 * An Intelligence of 8 is needed to trick Silus into thinking the Courier is an agent of Caesar's Legion on a mission to kill him. Silus will take the bluff and inform the Courier about Caesar's brain tumor and indirectly about Ronald Curtis.
 * An Intelligence of 8 is required to deduce that Dr. Mobius scattered the Sink personality chips across Big MT when talking to Dr. Klein during Welcome to the Big Empty.
 * An Intelligence of 8 is required to identify the purpose of Dog and God's use of the Villa police station alarm.

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.