Intelligence

Intelligence is one of seven primary statistics in the SPECIAL system.

Fallout, Fallout 2 and Fallout Tactics
Modifies: the number of new skill points per level, numerous dialogue options, and many skills.

One of the unique qualities of Fallout and Fallout 2 is the difference in gameplay caused by creating a low-Intelligence character. With a dimwitted player character, many non-player characters will simply shrug one off, while others will insult or even attack them. On the other hand, certain characters will take pity on the character's stumped intellect, and might treat them as innocent children. In some cases, where a character with normal vocabulary would need to persuade them or offer a service in exchange, these characters will often give the character gifts or allow them entrance in certain areas for free out of pity.

Ways to increase Intelligence

 * In Fallout, the Brotherhood of Steel doctor in Lost Hills can perform an operation to permanently increase Intelligence by 1, assuming it can be afforded. The surgery can be done twice, assuming the Vault Dweller has an Intelligence below 4 the first time it is performed.
 * Intelligence can be raised permanently in Fallout 2 in three ways. First, by using ACE and the yellow memory module (+1). Second, by the Hubologist zeta scan/alignment in San Francisco (which can also provide +1 Luck, though the game may need save-scumming to get a bonus rather than a penalty). The last method is to take the Gain Intelligence Perk. The bonuses from these methods stack for a total of +3 Intelligence.
 * In both Fallout 1 and 2, it can be increased by +1 for purposes of dialogue only, by taking the Smooth Talker perk.
 * In both Fallout 1 and 2, Mentats can be used to temporarily raise Intelligence by 2.
 * In Fallout 2, Intelligence can be temporarily raised by 1 point by the Purchase the Kesting Special quest given by Miss Kitty in the Cat's Paw brothel.

Fallout 3
Modifies: Medicine, Repair, and Science skills, as well as the number of new skill points per level.

Intelligence determines the number of skill points earned per level up. The base number of skill points gained per level is 10 + INT. Skill points gained for raised Intelligence are not retroactive for past levels, so increasing this primary statistic early, if at all, is the best. Also, temporary modifiers to Intelligence (e.g. from Night Person or Button's wig) do not affect the number of skill points gained when leveling up.

Ways to increase Intelligence

 * Permanent
 * Bobblehead - Intelligence (+1)
 * Intense Training perk (+1 per rank)
 * No Weaknesses perk (will raise base to 5 if below 5.)
 * Almost Perfect perk (will raise base to 9 if below 9.)
 * Temporary
 * Button's wig (+1)
 * Lincoln's hat (+1)
 * Berry Mentats (+5)
 * Mentats (+5)
 * Night Person perk (+2 between 6:00 PM and 6:00 AM)

Fallout 4
300px Unlike in previous games, Intelligence has no effect on skills, since Fallout 4 lacks a separate set of scores for skills. Instead, a higher Intelligence—in addition to unlocking higher perks in the Intelligence category—will increase the amount of experience the player character earns from all sources.

The experience multiplier linearly increases from 103% (1 Intelligence) to 130% (10 Intelligence). In other words, it increases XP gains by 3% per INT. It continues increasing if Intelligence is brought higher than 10. In math terms:
 * $${\it XP}_{\rm Final} = {\it XP}_{\rm Base}\times \left(1 + \frac{{\it Intelligence} \times 3}{100}\right)$$ A higher Intelligence also reduces the number of words that are displayed while hacking a terminal.

Ways to increase Intelligence

 * Permanent
 * Level (+1)
 * Intelligence bobblehead (+1)
 * You're SPECIAL! book (+1)


 * Temporary
 * Armor and clothing
 * Liam's glasses (+2)
 * Lab coat (+2)
 * Press cap (+1)
 * Road goggles (+1)
 * Ushanka hat (+1)
 * Mechanist's helmet (+1)
 * The Captain's Hat (+2)
 * Inquisitor's cowl (+1 up to +4)
 * Legendary armor effects
 * Chems
 * Berry Mentats (+5)
 * Mentats (+2)
 * Daddy-O (+3)
 * X-cell (+2)
 * Perks
 * Night Person (+2/+3 at night)
 * Settlement objects
 * Vault 88 overseer's desk (+1)

Ways to decrease Intelligence

 * Temporary
 * Armor and clothing
 * Chems
 * Dirty Wastelander
 * Beer
 * Settlement objects

Intelligence in quests and exploration

 * The Last Voyage of the U.S.S. Constitution has multiple intelligence checks that can speed up progression through the quest. Instead of replacing components, the player character can repair them instead. This strategy applies to the replacement of the wires (requiring an Intelligence of 5) and radio antenna (with a score of 9 INT).
 * When romancing Magnolia, she may compliment the player character's intelligence if the score is their highest SPECIAL attribute.
 * When repairing the decontamination system in Ablutions, an INT of 7 or higher can be used to make the decontamination arches remove radiation.

Fallout 76
Modifies: Item Condition and Durability, Ability to Hack Terminals, and Scrapping Return

Raising Intelligence decreases the number of words when hacking terminals.

At an Intelligence of 1, there is a +0% crafted item condition bonus. Each additional level of Intelligence increases this condition bonus by +5%, except for the jump from Intelligence = 4 to Intelligence = 5, where the bonus increases by +10%. At the maximum Intelligence of 15, the crafted item condition bonus is +75%.

Effects on scrapping yield
A higher level of Intelligence increases the return from scrapping items.

Ways to increase Intelligence
Note that all stat boosts in Fallout 76 are temporary.
 * Bobblehead: Intelligence (+2 for 1 hour or 2 hours with Curator)
 * Armor and clothing:
 * "Casual" underarmor with a treated lining mod (+1)
 * "Casual" underarmor with a resistant lining mod (+1)
 * "Vault suit" underarmor with a resistant lining mod (+2)
 * "Casual" underarmor with a protective lining mod (+1)
 * "Vault suit" underarmor with a protective lining mod (+2)
 * "Casual" underarmor with a shielded lining mod (+3)
 * "Vault suit" underarmor with a shielded lining mod (+2)
 * Legendary Effects:
 * Intelligence (+1)
 * Mutations:
 * Egg Head (+6)
 * Herd Mentality (+2 if grouped, -2 if solo)
 * Perks:
 * Night Person (+1 to +3 during the night)
 * Consumables:
 * Food:
 * Brain bombs (+3)
 * Brain fungus soup (+2)
 * Broiled scorchbeast brain (+3)
 * Owlet nuggets (+1)
 * Scorchbeast mixed meat stew (+1)
 * Drinks:
 * Simple aster tea (+1)
 * Steeped aster tea (+2)
 * Chems:
 * Berry Mentats (+5)
 * Daddy-O (+3)
 * Mentats (+2)
 * X-cell (+2)

Fallout Shelter
Intelligence affects how efficient a dweller is while working in the medbay and science lab facilities. A dweller's Intelligence can be increased by assigning them to the classroom.

Fallout: The Board Game
Unlike other games, Intelligence is not treated as a variable ranging from 1 to 10, but instead as a token that can be obtained at the start or when leveling up. A player character with the Intelligence token gets free rerolls during certain tests, as well as during fights if equipped with an Intelligence-based weapon. They can also recruit certain companions from the shop.

The Brotherhood Outcast player character always begins the game with Intelligence. Any player character wearing the lab coat gains one hit during an Intelligence test. During any Intelligence test, Mentats can be used to gain one free hit.

Intelligence-based perks

 * Gun Nut
 * Nerd Rage!
 * Swift Learner

Intelligence-based weapons

 * Alien blaster (x2)
 * Fat Man
 * Laser rifle
 * Plasma gun

Companions requiring Intelligence

 * Loadlifter
 * Protectron

Fallout and Fallout 2
When the player character in Fallout and Fallout 2 has less than 4 Intelligence, the biggest change in gameplay is undoubtedly the dialogue. Upon reaching Shady Sands, the villagers take pity on the Vault Dweller, and Aradesh will simply shrug them off. The best they can speak is half-word sentences or gibberish. This makes for some unique dialogue with the Overseer while attempting to return the water chip.

It is possible to complete the game as an idiot, but most side quests are impossible to do, and character growth is limited, as is the story involvement possible - while it is possible to bumble through the main quests, almost all plot details and background information will be left missing. Furthermore, due to limited-at-best non-player character interaction, almost all side quests are unavailable.

Talius at the Boneyard will gift a low Intelligence character with some mentats, and Darrel at the Lost Hills bunker gives them Rad-X. Additionally, during Dr. Lorri's surgeries, a Vault Dweller with low Intelligence will fittingly receive a 50% discount on the Intelligence boosting implant, lowering the price to 3000 caps.

The only companion available to stupid characters is Dogmeat.

The real downside, though, is the nigh impossibility to do about 90% of the side quests. No one will talk to a moron or even give them the time of day.

In Fallout 2, the Chosen One may meet Torr, the "town simpleton of Klamath," who would normally give them a quest to help protect his brahmin against "the evil bugmen." If the player character has low Intelligence, however, he will appear to be highly intelligent as if being stupid has a culture and language of its own. Two flat-headed people can have a complete, thought-provoking, and fully articulated conversation between them.

Another person one may have an "intelligent" conversation with is AHS-9, who becomes able to understand what the Chosen One tries to say after the alignment, and gives the quest to kill the Shi Emperor.

At the Den, low Intelligence characters still have the option to become a Slaver, and they will still receive a reward from Becky for killing Metzger. Killing Metzger is also the only way for dim-witted characters to free Vic, and he will still be available as a potential companion regardless of Intelligence.

For idiot players, the quest Something strange is happening at the farm northeast of Modoc. Investigate and report back to Jo becomes much easier. It will be presented to them while talking with Jo at Modoc. If they agree, all they have to do is travel to the Ghost Farm and talk to Vegeir. It is followed by Deliver Slag message to Jo in Modoc. One will be rewarded with the location of the Gecko town, which Jo mistook for a G.E.C.K. They will also receive an additional reward for completing the quest Farrel has a rodent problem in his garden. Remove the infestation, a cookie.

At Vault City, Skeev will try and enslave a stupid Chosen One. If one allows it, they will trigger a brief cinematic at the Servant Allocation Center with Barkus, before being automatically transported to Vault 8. If the auto-doc in the courtyard has been repaired, then the unmarked quest Auto-Doc Rodeo becomes available. This quest gives 2 unique perks which are determined by ones Luck stat.

A stupid Chosen One will speak a unique stupid line after hitting Lumpy at Broken Hills with their Highwayman. This is interesting, as one will need to boost their Intelligence via the use of Mentats in order to purchase and repair the Highwayman first. The mutant sheriff of Broken Hills Marcus, may become provoked if insulted by a stupid character, which makes him turn hostile.

When talking to Algernon in the basement of New Reno Arms, the Chosen One can start a childhood "cop and robbers" type dialog in which they accidentally "shoot" and kill him.

"Take care of Officer Jack" for Mira is a unique quest available only to player characters with an Intelligence stat of below 4 and a Strength stat of 7 or above. Also, the quest Retrieve Parts/Gain Access to Vault 15 is still available and one can still have a somewhat normal conversation with President Tandi at the NCR town.

Gruthar allows the Chosen One to enter Vault 13 freely, after realizing that they are clearly mentally handicapped.

Low Intelligence characters are presented with an additional option when it comes to completing the Navarro quest You need to use a FOB to access the navigation computer. They can lie to the base commander's room guard after they are mistaken as clean up crew, allowing them entry to his room. Unique dialogue is also present while conversing with the sympathetic quartermaster.

A character with a low Intelligence is unable to gamble. When they observe a roulette table or a slot machine, the character will respond to it as a fun toy or an interactive character, respectively. Visiting a craps table will result in a dumb Chosen One commenting to the dealer that they "play craps in pants".

Fallout 3
In Fallout 3, there are conversation situations where characters with low Intelligence are granted other dialogue options, often relating to their low intellect. One instance is in Roosevelt Academy, where if the Lone Wanderer activates Dean Dewey while having an Intelligence below 4, he will deem them a "special needs" child, and escort them to a "proper room."

Fallout 76
Similar to Fallout 3, low Intelligence checks are involved in situations where characters with low Intelligence are granted other dialogue options, often relating to their low intellect. Checks range from +4 to even negative Intelligence, going from -1 to -7.