The following is a list of secrets, easter eggs, and hidden trivia references in Grand Theft Auto IV.
- Car on Happiness Island
On the west side of Happiness Island, there is a random spawn that can be a car. This is unusual as there is no way a vehicle can be brought on to the island unless unloaded by a ship.
- Sultan RS behind an abandoned mansion
Behind an old, rundown mansion in Westdyke, Alderney at the end of the dirt roads, there is the hidden, extremely rare Sultan RS parked in some bushes. This is practically the only way to find the car ingame. The only other way to obtain it is if the game has it stored in the temporary memory (perhaps because one appeared in one of Brucie's Races), and automatically spawns it parked or driving around the streets.
- Re-start a breakdown vehicle by phone
If your vehicle has been damaged to the point that the engine has stopped, calling any number on the mobile phone will start it again. This does not work if the car had set on fire.
- Face of the statue & the Hot Coffee
The Statue of Happiness' face bears a striking resemblance to former U.S. Secretary of State Hillary Clinton. This resemblance, along with the cup of coffee in her right hand, may be a reference to the Hot Coffee controversy which Clinton took investigation in, also suggesting that new regulations be put on video games.
- "No Hidden Content This Way" sign
- Heart of Liberty
Within the Statue of Happiness is a giant beating heart, supposedly the "Heart of Liberty City." In GTA IV, access into the area is only achievable via an entrance marked by a "No Hidden Content This Way" sign at the upper level of the statue's pedestal, which can only be reached by helicopter. Once inside the pedestal, the player must scale a ladder up to the midsection of the statue, where the heart is located. It can be shot at, but nothing happens. In The Ballad of Gay Tony, if you drink too much, you will re-spawn at random locations, one of which may be the Heart of Liberty City.
- Maverick's warning message
There's an unsettling warning message about the Maverick inside the cockpit that you can see if you look in first person mode that says:
"This helicopter might crash but we really don't care if it does, refer to flight manual for help."
|Packie's Brain-Box. (with animation)|
- Packie's brain-box
If the player positions the camera in such a way that you can see inside Packie's head, you will see a small cube with Packie's balaclava texture from Three Leaf Clover.
- Strippers' black-box
Similarly as Packie's brain-box, some of the strippers has a little black box inside their head.
- Police Brutality
Inside the East Holland LCPD Station you can see three cops and someone on the ground. Another police brutality can be found at the northern beach of Boulevard, Bohan.
- Burger Shot disclaimer
Under the menu of Burger Shot you can see the disclaimer:
"This Burger may kill you! We can't be held responsible"
- Car wreck off the cliff
At the end of the street in south side of Beachgate, over the broken fence, there are two car wrecks off the cliff.
- Statue capped with traffic cone
Inside the courtyard of Civilization Committee Building at Hatton Gardens, there is a statue with a traffic cone on it's head.
- Epitaph of Grant's Tomb
In Middle Park West, The epitaph of Grant's Tomb is "We Love To Fight" instead of "Let Us Have Peace".
(In-game website mentioned about Ulysses S. Grant)
- Tomb of Meadows Park Church
In the graveyard behind the Meadows Park Church, there is a tomb or cenotaph with the epitaph below:
Roll of Honor "War of the Deadline" 1869-1869
"for those about to build...... we salute you"
- Tai Chi on the rock
On the huge rock of the beach in south-east Westdyke, there is always somebody practicing Tai Chi on it.
- Impregnation warning sign
At the Eugenics' warehouse in Port Tudor, a warning sign placed at the north-west corner of the building, wrote:
"Ladies! Please wear protection.
It's unlikely but not impossible you may be impregnated upon visiting Eugenics Inc."
- Photocopier in TW@
At all TW@ internet cafes, behind the cashier's desk, and also inside various vehicle dealerships, the screen of the Kakagawa Power Ultra 3000 Pro photocopier reads: ERROR Unleash ninja guru lol. This can only be seen through the scope of a Sniper Rifle.
- Mr. Tasty & the GTA IV theme music
While driving the Mr. Tasty, you can trigger songs to play by clicking the horn. One of these songs is the theme song of GTA IV. While this song is playing, call ZiT and they will text you back with "ZiT! Spotted GTA IV Theme". This is a cheat that gives the player health, armor and ammo, but also disables some achievements.
- Blood trail behind Faustin's house
If you walk to the backyard of Mikhail Faustin's home, you will found out there are two blood trails on the ground.
- The rules of Outlook Park
At the entrance of Outlook Park, you can see a sign with the rules:
no eating, no drinking, no dogs, no children, no ball games, no hotdogs, no running.
- The most expensive kids meal
The highest price meals in Cluckin' Bell restaurants is "Little Clucker" ($8.00) and "Little Peckers" ($8.00), both of them are meal for kids.
- Veggie Wings may contain meat
The Cluckin' Bell new "Veggie Wings" with a row of disclaimer below: "may contain meat".
- Clean Hands, Clean Conscience
On the paper-towel dispenser in Cluckin' Bell restaurants with the text of "Clean Hands, Clean Conscience".
- Cash register in Cluckin' Bell
On the cash register of Cluckin' Bell restaurants, you can see the text on it likes: "Holy Shit", "Veg Crap", "Medium, Extra Medium, Medium XL", "Ask CJ", "Launch Missiles", "Space Lazer" etc.
- Plaques of the fossils
There is an easter egg in The Libertonian; the plaque describing the Tyrannosaurus Rex and Triceratops. The texture of the text is low-resolution, and thus hard to read properly, but reads, roughly:
"This big bastard took a few days to knock up because it had to be done by the sole hand of a prop artist. But alas, and feast your eyes on this 21000 poly maniac. Trex right up your arse. How do you like them apples?".
- Prison chart
In the missions done for Gerald McReary while he is in prison, a chart can be seen behind Gerald during the cutscenes for the mission. There are several names written on it, all of which are puns, including "Isaac Hunt" (I's a cunt), "Seymour Fani" (see more fanny), "Richard Head" (dick head), and "Phil Mcreavis" (fill my crevice).
- In the night sky
If the player scopes the night sky with a sniper rifle on a clear night, they will find some galaxies, stars and a flying thumb, in the thumbs up position.
Easter eggs references to previous games
|Graffiti found on certain run down apartment corridors.||A modified version of the above image.|
- The "RIP/we'll miss you" graffiti
On the staircases in most apartment blocks in the game, you may spot some graffiti referring to past protagonists set in GTA III canon (Claude, Tommy, Carl (CJ), Toni, and Vic), that suggests they have passed away, though it is likely metaphorical as GTA III canon is over so they won't be seen again. The only onscreen death of a protagonist so far is Victor Vance and Johnny Klebitz . The graffiti is intended to serve as "a little joke for fans of the series", as a different design approach to GTA IV meant the games' timeline could only inherit various fictional brand names and certain radio personalities; it is, however, no indication as to whether or not GTA III canon has been retired.
- Myths from San Andreas
There is a Liberty Tree article that talks about urban myths in Liberty City. This could be referring to the myths that were created around San Andreas.
One of the in-game radio advertisements is for an online service called Babiesovernight.com. The tagline at the end and the background music are evocative of the commercial in GTA III for Petsovernight.com.
- Claude's outfit
When Playboy X is killed, it is possible to go to his apartment and open the wardrobe to get a change of clothes that look like the clothing of Claude, the protagonist of GTA III.
- Miniatures in Miniature Golf Course
In the miniature golf course Funland amusement park, several miniatures are re-use from previous GTA: (from left to right)
Jefferson Towers (GTA SA); windmill (several different place in GTA SA); "The Big Pecker" (GTA SA); Ocean View Hotel (GTA Vice City); Los Santos Lighthouse (GTA SA)
- Street-artist's artworks display
On Happiness Island, in front of the entrance to the statue, it is possible to find a street-artist's easel/display stand with several pictures. These pictures are all concept works of many previous GTA characters. The easel can also be seen in south-central Algonquin, very close to where Hossan's random encounter takes place and in front of the The Libertonian.
- Hot Coffee in Liberty City
There are signs scattered throughout Liberty City that say "Hot Coffee Shop", clearly a reference to the Hot Coffee sexual content and controversy from GTA San Andreas
- San Andreas on TV
One of the TV shows is a program called The Venturas Poker Challenge. It features a casino in Las Venturas from GTA San Andreas. When shown, the commercial doesn't have GTA IV graphics and art, it features GTA San Andreas graphics, the most obvious being the building designs and taxi. Similarly, footage of the Vinewood sign from GTA San Andreas is used for another TV ad; it is recognizably San Andreas animation due to the transmission tower visible right behind it, which was also in the earlier game.
Niko can receive an email from Chiliad8888, which calls the recipient "Pilgrim", makes many spiritually- and philosophically-charged (and anti-government) comments, ends with "Feel the Truth, Live the Freedom", and links to whattheydonotwantyoutoknow.com. On this website there is a discussion topic titled, "Jump to a new level of Spirituality" posted by "Trooth". This discussion thread includes more philosophical thoughts, mentions Peyote, and provides a map of the Unique Stunt Jumps in Liberty City. "Chiliad" was also the name of a location in San Andreas (the highest mountain, in the southwestern wilderness). These clues suggest that the author of the email and discussion topic is The Truth, a character from GTA San Andreas.
- Drawing on prison chart
If you look closely at the chart behind Gerry on the prison, you can see the penis-shape drawing the students in GTA III had drawn.
- Ringtones referring previous games
The "Pager" ringtone on Niko's cell phone is the pager sound from GTA III. Vipluxuryringtones.com offers MP3 ringtones of songs from Lips 106 and Head Radio in GTA Liberty City Stories.
Elements re-used from previous games
- GTA's musicians
CDs from pre-GTA IV musicians are found in different places in GTA IV: Madd Dogg - Still Madd and OG Loc - Str8 from tha Street, both rappers in GTA San Andreas. Rudy LaFontaine - Funk in Time and Sunshine Shine - Mine Until Monday can both be heard on Lips 106 on GTA Liberty City Stories, and Purser - Feel the Pain can be heard on Head Radio on LCS.
- Mr. Wong's Laundromat
There is a laundromat in Broker called Mr. Wong's Laundromat; this is presumably a nod to that particular location. You also park infront of it in the TLAD mission Roman's Holiday.
- Gruppe Sechs
The Securicars are owned by the Gruppe Sechs security firm (also seen in GTA III Grand Theft Auto: Vice City and GTA V), although in GTA IV and GTA V the name is rendered as "Gruppe 6". "Sechs" is the German word for Six and "Gruppe" means group.
- Donald Love is back
On the front of the Liberty Tree is Donald Love, who disappeared in GTA III.
- CJ billboard
A Fruntalot billboard outside the Algonquin safehouse shows a man ressembling CJ, drinking wine.
There is a Sprunk manufacturing plant in Alderney and a vending machine at Romans taxi depot. Sprunk was featured in GTA Vice City, GTA: San Andreas, and Manhunt. It has returned to GTA IV with a brand new look. Also notice that "Sprunk" is a mix of the words "Sprite" and "Spunk". The sign outside the factory is very similar to a sign for Pepsi-Cola that appears in the film "The Great Gatsby."
- Love Fist
In Star Junction there is a sign for Love Fist. Love Fist was featured in GTA Vice City, and was also on a sign in GTA San Andreas and GTA Liberty City Stories.
- San Andreas mentioned
During a multiplayer race in GTA IV if the player equips a certain Female face (possibly 2) then hits a car in traffic or another player's car while pressing the talk button ( PS3 or LB Xbox 360), the character will sometimes exclaim, "This isn't San Andreas you hippie, DRIVE!"
- Vice City postcards
In the bars are postcards featuring Vice City. Vice City is also advertised in airfare billboards near the airport.
Easter eggs references to other games
- Republican Space Rangers
On the TV channel Weazel, there is an animated TV show called Republican Space Rangers, which spoofs the Halo series, as it features space marines wearing a green armor that resembles the MJOLNIR armor as seen in Halo. In one scene, the Rangers fly their spaceship through a ring that resembles a HALO ring.
- Artworks of Videogeddon
On the wall in the arcade place Videogeddon in Chinatown, there are several sprites on the wall resembling those of old games. One of the sprites is a blond man, with a long mustache and plumber-like black clothes. The sprite resembles Super Mario from the Super Mario Brothers series.
- Purple Hippo trash can
In the amusement park in Broker there are blue/purple Hippo Statues, just like the ones from Manhunt.
- Carcer City
Numerous references are made to Carcer City, the setting of Manhunt.
- Manhunt in Liberty City
The achievement/trophy for completing all the most wanted side missions is called Manhunt.
- Drugs from Manhunt
On the website Yourmexicandoctor.com, two drugs first seen in Manhunt 2 (Hingmyralgan and H4PP1) are shown to be for sale.
- "Well excuse me dorkwad!"
Certain random female NPCs will, upon being pushed, exclaim "Well excuse me dorkwad!", a possible reference to the Legend of Zelda cartoon.
- Jimmy Hopkins-a-like with Bullworth Academy vest
A pedestrian bearing an uncanny resemblance to Jimmy Hopkins, the protagonist of Bully, can be seen roaming the streets of Liberty City. He is even wearing a Bullworth Academy vest. He is, however, much more aged but does have a similar buzz cut hair style.
Easter eggs references to media culture
- Cluck Norris in Cluckin' Bell
In Cluckin' Bell restaurants, near the back of the store, there's an action figure of a man in a martial arts position wearing a chicken hat; printed on the glass is "Cluck Norris", a reference to film/television star and martial artist Chuck Norris.
- Madness & Blasphemy: The Do's and Dont's
In the second apartment you unlock (Located in Bohan), there are books sitting on a table near the TV. Shoot one of the books and there is another underneath titled Madness & Blasphemy: The Do's and Dont's written by Nuck Chorris. This is also a reference to Chuck Norris. The title of this book also makes reference to Frank Miller's film 300, where Leonidas' famous "THIS IS SPARTA!" shout was preceded by "This is blasphemy! This is madness!"
- Rhapsody's sticker (TLAD)
In The Lost and the Damned, the dash of the Rhapsody has a sticker of Wayne and Garth from the movie Wayne's World, which famously features the song Bohemian Rhapsody.
- Real-world graffiti: Banksy-esque
On the stairway leading to the sea at Meadow Hills there is a 'Banksy-esque' style graffiti piece.
- Real-world graffiti: Cope
On many alley walls there is graffiti that says 'Cope' a famous graffiti artist in the real world.
- Rockstar Games's logo
Rockstar Games has a habit of putting its logo in its games; the bowling pins at the bowling alley have the Rockstar logo on them.
- Wilhelm Scream
In the mission Final Interview, if you shoot the guard standing at the top of the last flight of stairs when escaping from Goldberg, Ligner & Shyster, he will do a Wilhelm Scream as he falls down.
- "Hey! I'm walking here!"
At the beginning of Clean Getaway, Vlad is nearly hit by a taxi and shouts "Hey! I'm walking here!" in reference to the movie Midnight Cowboy.
- "I'm gonna be okay!"
When you wound a cop sometimes they will shout "I'm gonna be okay!", referring to Reservoir Dogs, when Mr. Orange is shot in the abdomen and is screaming in delirium.
- "If I was that big chimp, I would climb it too."
If you go on a Heli Ride with Brucie, and if you go to the Rotterdam Tower, Brucie might say "If I was that big chimp, I would climb it too." This is a reference to King Kong.
- 2 Girls 1 Cup referenced
The viral video, 2 Girls 1 Cup, is indirectly referenced to numerous times on the radio.
Mission name references to media culture
- Concrete Jungle
Named after the hit song of Bob Marley. The song is also in the official soundtrack. Also, if the mission for some reason fails and is restarted, Little Jacob will, on the drive back to the Homebrew Café, refer to the underground of Liberty City as "a messy concrete jungle".
- The Master and the Molotov
A reference to Michail Bulgakov's book "The Master and Margarita".
- Crime and Punishment
Named after Fëdor Dostoevskij's book "Crime and Punishment".
- The Puerto Rican Connection
A parody of the movie "The French Connection".
- Portrait of a Killer
A reference to Patricia Cornwell's Portrait of a Killer - Jack the Ripper: Case Closed book.
- Holland Nights
A homage to Eddie Murphy's movie "Harlem Nights.
- Weekend at Florian's
It is a reference to the comedy movie Weekend at Bernie's (Florian insists that his new name is Bernie).
- I Need Your Clothes, Your Boots and Your Motorcycle
It is a reference to Terminator 2: Judgment Day, in which Arnold Schwarzenegger says this famous line.
- To Live and Die in Alderney
A reference to William Friedkin's movie To Live and Die in L.A..
- Diamonds Are a Girl's Best Friend
A reference to the movie Gentlemen Prefer Blondes with Marilyn Monroe.
- A Dish Best Served Cold
From the famous adage "Revenge is a dish best served cold".
- If the Price is Right
A reference to the American TV game show The Price is Right.
- A Revenger's Tragedy
A reference to the Jacobean revenge tragedy The Revenge's Tragedy of 1606.
- Concrete Jungle
Easter eggs real-world references
- For GTA IV's renditions of New York City landmarks, see Liberty City in GTA IV/New York Landmarks.
- Tom Goldberg the lawyer
In the mission, Final Interview, the lawyer Tom Goldberg, which Niko has to kill on orders of Francis McReary, is supposedly based on a real-life disbarred lawyer, Jack Thompson, who is an activist against violent video games for minors and is a well known arch-enemy of Rockstar. One of the lines Goldberg says when Niko pulls out a gun during the interview is a real-life reference to one of Thompson's famous lines against violent shooting games that are "murder simulators" is "Guns don't kill people, video games do!"
- Double your breasts
In Cluckin' Bell, the slogan of "The Mighty Cluck" is "200% bigger breasts", referring the rumor about the KFC's chickens pumped too much hormones and cause the customer with larger breast even for men.
- 212 passengers
An online article on Liberty Tree's website, an Air Sol flight has 212 passengers on board, 212 a reference to the area code in New York City.
- Economic recession of United States
The game references to the economic recession faced by the United States on a few occasions.
- Al's Furniture
In Willis, there is a shop called Al's Furniture. This is a reference to Italian-American gangster Al Capone, who was officially the owner of a furniture shop.
- Paper factory as a cover
The fact that a secretive government body operates out of a paper factory may be a reference to the TV show Heroes. A secretive organization in that show also uses a paper factory as a cover and much of the action takes place in New York.
- Smoke outside complains
There are a lot of people complaining that they have to smoke outside. This is a reference to New York City, where you can't smoke inside either.
Easter eggs about in-game street names
- In Broker, roads running North-South are named after Native American tribes—Iroquois, Oneida, Mohawk, Onondaga etc.
- In Broker there are the street names "Cassidy" and "Sundance", a reference to the outlaws, Butch Cassidy and the Sundance Kid.
- The Beatles: Broker contains the streets "Ringo St" and "Starr St", both references to the Beatles member Ringo Starr. In Dukes there's a Harrison St., probably a reference to George Harrison, and the northwest section of Liberty City contains the Long John Ave, name that John Lennon used at the beginning of his career. Paul McCartney references are not found yet. Also on the side of buses, there is a small ribbon saying "here, there and everywhere" which is a reference to the Beatles song "Here, there and everywhere".
- Many street names in Bohan are named after prisons—Leavenworth Ave, Alcatraz Ave, Sing Sing Ave, Guantanamo Ave, Attica Ave, San Quentin Ave, Folsom Way (best known from "Folsom Prison Blues" by Johnny Cash), Rykers Ave (named after the Rikers Island prison on the East River of New York City), and Joliet Street (Joliet, Illinois).
- Avenues running north-south (vertically) in Algonquin are named alphabetically after American cities. "A" is at the eastern side of Algonquin; "G" at the western. The names, in order, are Albany, Bismarck, Columbus, Denver, Exeter, Frankfort, Galveston. Denver and Exeter run concurrently ("Denver-Exeter Ave.") south of Middle Park into Star Junction.
- Streets running east-to-west (horizontally) in Algonquin are named alphabetically after different types of minerals. "A" is at the southern end of Algonquin; "X" at the northern end. The names in order are Amethyst, Barium, Calcium, Diamond, Emerald, Feldspar, Garnet, Hematite, Iron, Jade, Kunzite, Lorimar, Manganese, Nickel, Obsidian, Pyrite, Quartz, Ruby, Silicon, Topaz, Uranium, Vauxite, Wardite, Xenotime.
- In South Alderney, the street names reflect (mostly antiquated) military terms—Musketeer, Grenadier, Chariot, Phalanx etc.
- In Alderney, some streets are named after cult leaders: Hubbard St., Applewhite St., Koresh Square
- Some streets are named after tools—Jackhammer, Plumbbob, Tinderbox, Drill.
- Some streets are named after insects—Caterpillar, Worm, Butterfly.
- Some streets are named after foods—Onion, Asparagus, Chive.
- Some streets are named after colonial Settlements—Yorktown, Delaware.
- Some streets are named after famous surnames—Harrison, Hancock, Livingston.
- Some streets are named after nuclear tests—Plumbbob, Emery, Niblick, Ivy, Hardtack, and Trinity.
- Some streets are named after inventors—Edison, Schneider, Moog, Drebbel, Farnsworth, Cockerell.
- The street in Northwood named Astoria's full name is Astoria Place. This could possibly be a take on Astor Place in the Lower East Side.
Easter eggs about adult humor
As with previous games, the number 69 is used on various occasions in Liberty City, one such instance being on the Fire Trucks. 69 is a reference to the sexual position of the same name.
- The Clocktower
In BOABO, Broker, there is a building called, "The Clocktower" and it has a digital clock that displays the in-game time. When driving on the Algonquin Bridge at night, leaving Algonquin, you can see the word CLOCKTOWER lit up except the "L" is not lit and it says "COCKTOWER".
- Sign of Memory Lanes
The outside sign for the Memory Lanes bowling alley depicts a bowling pin with two bowling balls on either side of it. Inside, however, the sign is only a neon outline, and resembles a crude drawing of male sex organs.
- Pißwasser beer
Another beer brand is named "Pißwasser", "wasser" being German for "water" and "ß" is a German letter for "ss". An advertisement for Pißwasser shows a woman with the bottle in her mouth as if in an act of fellatio.
The logo for AutoEroticar is a car resembling a penis. The name also has the word "Erotic", saying that the cars are going to give you an erection.
The series of internet cafes known as Tw@, is a clear reference to the female vagina. When the "@" is pronounced as "at".
- Pawn Stars
There is a pawn shop in Lower Easton, Algonquin that is called "Pawn Stars", a innuendo for Porn Star. Many think it is supposed to reference the show "Pawn Stars" on History, but that show didn't air until after GTA IV was released.
- Monument in Middle Park
In Middle Park there is a monument that resembles male genitalia. According to a plaque at its base, it is called "Le Knobelisk" and was presented to Liberty City in 2007.
- Statue in National Union of Contemporary Arts
In East Island City, there is a building called the National Union of Contemporary Arts, within which is a statue of what looks like a stick figure man with an erection.
- Cluckin' Bell's restrooms
Another thing in Cluckin' Bell is the names above the restrooms. The male restroom says "Cocks" above it and the female restroom says "Chicks" above it.
- No chickens are choked
There is a sign of "No chickens are choked when preparing our food (That's a promise)" in the Cluckin' Bell. "Choke the chicken" means the act of masturbation.
- Cluckin' Bell's cock
Meals at Cluckin' Bell prefer to use the word "cock" instead of "chicken".
- Dildo on rubbles
In many spots around Liberty City, there is rubble on the ground; in some of this rubble, you can see a purple dildo sticking out. This is the same dildo used as a weapon in GTA San Andreas.
- Golden Pier Swingers Golf Club
Looking at the golf courses carefully from a height reveals that they are penis-shaped.
- Dusche Gold beer
A brand of beer in the game is called "Dusche Gold". "Dusche" is German for "shower", so it translates into "shower gold", a reference to "golden shower", the act of urinating on someone.
- Posters in hospitals
In hospitals, there are posters about sex.
- Bernis's flower picture
In Florian's (Bernie's) apartment, in his family room, there is a picture of a flower that represents the male genitals.
Easter eggs about languages
One of the restaurants is called "Viendemorte", which sounds exactly like "viande morte". It means "dead meat" in French.
Bugs & Glitches
- TVs in multiplayer mode
While playing multiplayer, some of the TVs in safehouses and the TV in the MeTV building, show the game's pause menu without the map.
- Firefly Projects' swing
At the Firefly Projects, there is a park with a swing set. If you drive backwards (or forwards with some vehicles such as a Voodoo) onto it, the swing set will catapult the vehicle high in the air. This is likely a bug in the game's physics simulation. See Swing Glitch article for more details.
- Runaway gangs
Normally hostile pedestrians flee. Go into any strip club and either shoot it up or spend some time with a stripper. Then go to areas where there are gang members that will become hostile if they are bumped. Punch them and they will run away. Drivers that normally would get out and try to hurt you if you punch or hit their car will also flee. This only has a temporary effect.