Invisible Walls

By Luca Breda [08.19.08]

 Immersion is a phenomenon in many kinds of media, though it is particularly relevant in virtual environments and video games. Immersion is a concept largely used to describe the player's status relative to the medium. However, there is more than one approach to how we define immersion.

Here, I discuss the utility of immersion and the capability of the environment to create it. Other works have identified possible barriers to immersion, and their effectiveness is debated here. I also look at several theories about maintaining immersion, such as the rule of consistency.

Immersion: Le Mot Juste
Being engaged in a video game, movie, virtual reality, or book is described as experiencing deep emotion linked to the medium. Usually this state is called immersion, but it's not always clear what is meant by immersion and if the meaning is used consistently.

"Suspension of disbelief," "flow," and "presence" are terms I use to signify different aspects of immersion, and although they possibly overlap in meaning, they are useful in reaching a more complete definition.

Suspension of disbelief. Samuel T. Coleridge nearly 200 years ago defined drama as "that willing suspension of disbelief for the moment, which constitutes poetic faith." It is a suspension of the critical intellectual faculties and a consequent distorted sense of time toward a better enjoyment.

Flow. A hundred years later, the psychologist Mihaly Csikszentmihalyi defined "flow" as the state in which "individuals are so involved in an activity that nothing else seems to matter." In this case, concentration is important for strong cognitive engagement by the player.

Presence, defined by Lombard and Ditton, is more related to technology than the human experience. It's the sense of being there, in a mediated environment that fulfils the stimuli to be perceived. When the perception of mediation vanishes or fails, the presence arises: a physic sense of location, engagement, and participation, characterized by naturalness and realism. "Presence" suggests the relation between a player and her environment through an interface.

Related to presence, immersion does not guarantee the illusion of non-mediation, but it helps. Per se, immersion suggests the need to eliminate external cues, though that alone is not enough to guarantee the illusion.

For the sake of clarity, immersion is meant here as a concept that incorporates all three of the concepts stated.

Factors of Immersion
I have identified the player's status in a particular moment with respect to the medium, physically and psychologically. However, none of these constructs suggests a measurement for how the player is immersed.

Four factors determine whether one reaches total immersion: attention, concentration, atmosphere, and empathy. A game player's level of immersion is a reference to the number of obstacles that hinder any or all of those four factors, so it is implicit that at intermediate levels, the player is not able to be fully immersed. In games, however, this is not always the case (which I will discuss more thoroughly later).

There are at least three types of immersion in games: short-term, long-term, and narrative.

Short-term immersion. Short-term immersion is physic and immediate. It arises when the challenge is simple and only a few seconds are needed to make a choice. A very intuitive and reliant interface is needed to support short-term immersion because clumsy controls and chaotic gauges are the main obstacles, as well as sudden changes in gameplay, such as a single stealth mission in an action-oriented FPS.

Long-term immersion. Long-term immersion is more cerebral and related to path recognition, an innate ability in humans. The player searches for paths to victory and assesses their efficiency, just as a chess player foresees a series of moves ahead of time, not just the next move. Being so immersed becomes a moment of watchful observation and deduction. The main obstacles here are illogical or aleatoric (chance, random) behavior -- things that prevent the player from formulating a long-term strategy.

Narrative immersion. Narrative immersion is more closely related to the kind of immersion found in literature and film because it is involves attachment to characters, actions, and plot. Unconvincing dialogue, unrealistic characters, and incomprehensible plots are the main deterrents.

The Purpose of Immersion

What is the point of immersion and its role in virtual environments and video games? Games are closed, formal systems that represent another world, according to Chris Crawford (1982), who also calls games "a subset of reality." They are simulations based on a limited set of rules, possibly different from reality. For example, as shown in the image, human flight may be possible without explanation.

These closed formal systems create a simplified representation of emotional reality, says Crawford.

Games are an interactive medium experienced with the body, which is our main interface to the reality of game. The stimuli in the simulation are what we use to judge the quality of the experience.

Realism arises in part from the player controlling a character or other on-screen representation of himself. If his actions render the expected result in the game, the player feels in control and perceives the game as real.

 The actions are perceived as "real" even when carried out in a fictional world. For this reason some kind of realism is important: the brain needs to be told that the virtual world is somehow genuine for the brain to decide how it should act and react.

If the player feels immersed and present in the world, his actions matter more than the mechanisms of the game. The player begins to act in the environment consistent to what he perceives in that environment. The environment becomes real per se and is no longer viewed as a set of stimuli and an interface.

Invisible Walls
The realism of the representation does not assure that a game player will achieve total immersion due to certain barriers, or invisible walls.

It's an emblematic situation. The passage seems clear -- nothing is in front of the player; and yet it is not possible move forward. For example, in the recent Kane & Lynch: Dead Men, a "clearly" open gate represents the exit that has to be passed to complete that game mission, but is not passable until the game says so and eliminates the obstruction.

These invisible walls are sometimes considered errors of level design because they are unforeseeable, irritating, and nonsensical. I extend the meaning of "invisible walls" to include all barriers that limit immersion, including those within the game system that are present without being visible.

However, I question whether all invisible barriers should be avoided in the first place for the sake of immersion. Some examples are common physical obstacles, gauges on the screen, stylistic and narrative solutions -- anything that constitutes a layer between the player and the game space. Are they the deterrents to immersion that they seem to be?

Other authors writing about video games have correctly noted the discontinuity in immersion in games because of these obstacles. But what follows is a number of examples of invisible walls that seem to support immersion as much as they detract from it.

HUD. A recent trend in game UI has been to remove some or all of the heads-up display elements on screen (as was done in Peter Jackson's King Kong, shown). The idea is that HUD elements distract the player's view from the focal point, because they are typically placed on the screen's periphery. The more the screen is overloaded with HUD elements, the more built up the layer between the game and the player is. Few games have gone so far as to remove all or most HUD elements, though Metroid Prime and Doom 3 are examples of games that shifted toward this.

Obviously, this trend has its pitfalls. HUDs are familiar interfaces to game players, and a total lack of this interface leaves the player without necessary information for play.

The main concern is not questioning that HUD elements help immersion, but that having some of them do not harm immersion, as many authors have agreed.

To my knowledge, no authors have argued that HUD elements help immersion, but many have agreed that having some HUD elements do not harm immersion. Even when the elements are integrated, the player still has an awareness of them, though this awareness become implicit when his focus shifts to the action. The HUD is therein accepted.

Locked doors. Another barrier to immersion is doors that cannot be opened. Grand Theft Auto and Saints Row are open-world games that have hundreds of buildings and thousands of doors. But not all the doors can be opened, usually for technical and gameplay reasons. This is often addressed as an immersion problem. However, in the real world, people do not have free access to all the doors in their cities, so why should players expect it in games? The real problem is the player's knowledge that there is nothing behind the closed doors in these games. All this is known among gamers, but usually not among casual players and non-gamers, who have not yet discovered the tricks implemented to reproduce so wide environments.

A closed door does not break immersion; it is only a supposition. It's possible to make clear visually whether a door can be opened, but this only helps improve player usability, not immersion. Believing in the illusion is up to the player.

In Call of Duty 4 (see image
), a series of barriers is used along the borders of the levels to limit the playable area. The player is not able to jump over the barriers. However, the same barrier shows up again in the middle of the level, where the player can jump over it. Players know this because the game explicitly informs them that by pressing the space bar, they can leap over it.

Perhaps using a different style of barrier for the jumpable object and for the borders would have been a more elegant solution, but this slightly inferior solution doesn't totally destroy the illusion of the world. Players know when an area is closed off; using barriers for that purpose is a known and accepted convention. Only usability is harmed in this case because there the only thing that differentiates the two types of barrier is an icon, which is quite a minimal distraction to an engaged player.

 Glimpses beyond the immediate. Usually in linear games, the player gets glimpses of scenery beyond their immediate environment by looking through windows, grates, and over walls. These are fake panoramas used to support the notion of a wide-open game world. Experienced players know it's only a trick and that nothing exists other than what's immediately visible. But conventionally speaking, these glimpses provoke the player into finding a better vantage point.

This happens in Half-Life 2, although in that case, the game has skilfully enhanced the situation. The player can see locations through grates and windows, but before or after he arrives there physically, increasing the sense of reality through moments of recall.

When we play games, our level of immersion changes based on real world contexts, too. Playing Doom or Quake today leaves us with a much lower sense of immersion than it had in the past, based on our level of expectation for an immersive game experience.

Anachronistic content break immersion as well, in the sense of suspension of disbelief. On the other hand flow might remain intact regardless, because gameplay ages at a slower rate than graphics. Nevertheless, there's no denying certain cases of dated gameplay, particularly in games that had a poor balance between the challenges presented to a player and the player's assumed skills.

Hit points. Another example of something that might break immersion is hit points. Hit points are the predetermined number of hits to complete a task; for example, slaying a demon might require exactly 10 hits with a sword to die, or killing a soldier requires two hit with a shotgun.

Theoretically, hit points should break immersion, but it's probable that a majority of players don't mind it. Likely players are accustomed to the logic of the gameplay, or they have not come across an alternative way of accomplishing the same goal.

Repeated obstacles. It would seem that objects and obstacles that re-appear frequently in a game would make a player aware that she is playing a game. However, the brain is able to cut out peripheral details, when and how it is needed. If a player is motivated enough, repeated obstacle and objects can be assimilated and accepted. For example, when a player finds yet another invisible wall in Killzone or Battlefield 2, it doesn't come as any big surprise, and he moves along.

Style. Another type of barrier is related to style. The postmodernist effects in Metal Gear Solid remind the player that he is playing a video game. These self-indulgence interferences from the designers into the player’s experience have no clear advantage for immersion. In theory, rather, the immersion should be completely broken. While the player is supposed to be deeply immersed in a deadly struggle to prevent a disaster (see the Metal Gear Solid plot), the designer interrupts to say, "It doesn’t really matter, after all." In theory, the immersion that might result should be completely broken, because of such external messages inserted during the gameplay.

In books, it's easy to immerse the reader using similar tricks; in games it's much more difficult. Rather, it's easier to break the "pact" than it is to maintain it.

The narrative style of Metal Gear Solid is not new. "Breaking the fourth wall," as it were (Figure 4), permits us to explore the nature of fiction. Postmodernism seems to break the narrative immersion, but it can make the gameplay more engaging by the very act of breaking immersion.

Silent Hill is an example: It has clumsy controls and grotesque images that heighten frustration and fear. The same is true of Call of Duty 4, when the player's viewpoint is temporarily limited, which decreases his freedom of movement. These kinds of disruptions can contribute to a more cinematic style, and they prove that immersion doesn't have to always be seamless.

In Devil May Cry 4, red web-like barriers (see image) appear magically from the ground and seal the area, until all the enemies are defeated. Players of the genre have become so inured to this incident and others like it that the loss of immersion is minimal. They simply accept, implicitly, that this is a law of a magical world.

Resurrection and the disappearance of corpses from the ground are two other major clichés in games. "Rapid decomposition" is often used as an explanation -- and no matter how hackneyed it seems, it is in theory at least somewhat believable, and they player accepts it.

Immersion and Perception
Achieving and maintaining immersion is the result of many factors. An effective interface has to supply multi-sensory and reliable information, accurate and quick responses to user actions, and provide feedback in the form of virtual results that is coherent and consistent in the game world. Audio effects play a part as well, helping to create a credible environment.

Increasing the number of senses used does increase immersion; increasing only visual information is not enough. The Nintendo Wii has moved toward goal by incorporating more of the body and its actions in the on-screen play.

 Yet immersion can take place even with poor immersive interfaces, such as keyboards and mice, thanks to other factors: emotive investment, attention, empathy, coherence, and naturalness. The semantic content of environments has been found to supplement perceptual and technological factors. A good story can cover for a lack of perceptual wealth, as is demonstrated by Mass Effect -- there are no bathrooms in any of the apartments, and it doesn't matter.

The combination of sensory clues, embedded in the features of the environment, and well-known conventions can steer the player through a set of responses: the boundaries of play are established in terms of expectations of physics, agency, and context. This contract is needed in order to maximize the play experience and minimize processing capacity. For example, a combination of cues keeps the player aware of which objects are open to manipulation and which are not, without appearing to restrict exploration too much. The gap between virtual and real world is filled, and could be controlled the degree of freedom of action within the environment.

A full recreation of reality is furthermore undesirable. The "rocket-jumping" in Team Fortress 2 is a clear example of altering physic to heighten gameplay. Provided there is consistency, the contract between player and game is not violated. With such departures from reality, one of the key factors is the naturalness of the interface, because unexpected outcomes to user actions may hamper immersion. The player's expectations have to be evaluated.

Immersion and Affordance
A player's perception is mapped to the rules of the system rather than the limitation of the interface. The environment affordances are more important than the manipulation of mouse and keyboard.

Affordance is a technical word referring to the property of an object and the action that it seems to allow the player. A floor affords the action of walking and a door affords the actions of opening and passing through. It has been noted that the greater importance of the expected affordance, the greater the expectation of agency.

Often in games, the worlds are completely fictional and without much logic. In reality, things that happen in games are often not possible in the real world, but the affordance is overwritten by the convention. So for example, a character can "obviously" move an enormous slab of stone (see image above).

The player's experience as a gamer should be taken into account. Is he aware of similar actions and physical licenses in other games? Definitely games should render their own rules, because as Crawford's definition implies, players require an explanation of differences with reality.

Immersion and Consistency
Immersion happens thanks to the brain's willingness to forsake some knowledge of what's real and what's not. Consistency is a crucial aspect in game design. Consistency means that every element, background, key features of gameplay, artistic and technical direction, has to be coherent across a title.

Coherence helps the relationship between the player and the system. Incongruence may harm it. Playing a game is an expensive activity in terms of cognitive work -- to learn the environment, the characters, the mechanisms, the objectives, etc. For this reason, games follow conventions and make use of tutorials, thereby reducing their average difficulty and lessening the cognitive strain.

Inconsistencies waste the player's time and shock the player's attention, often shattering the sense of immersion. But if that were true, every usability issue would be disasterous to a game, and they're not. We have a certain threshold to account for usability. The concept of flow explains how the simple engagement allows for a cognitive, though possibly no less visceral, immersive response. During this state of immersion, minor usability flaws are no more detrimental. Further research is needed to establish the threshold at which the immersion is truly interrupted.

Immersion and Credibility
Consistency is not always enough to maintain immersion. I content that “credibility” is more relevant. Credibility pertains to the story as well the actions of the player. Actions must occur in a context that’s capable of tolerating a certain amount of improbability before the credibility "budget" is exhausted. Excessive use of unrealistic elements can ruin the player’s immersion; there is a limit to incredibility.

A universal and accurate definition of immersion is difficult to determine, even considering the constructs and the exceptions seen in the cases examined. Although other studies have (correctly) indicated that certain barriers can shatter immersion, my theory proposes a different perspective that shows unexpected counter-results.

Once achieved, immersion may help the player overcome other usability issues in video games.

Do we need invisible walls? Likely no, but their appearance in games is not as detrimental to the player's experience as they once were believed to be.

Luca Breda is a contract designer and developer, originally educated as a programmer at University of Udine, Italy. In his free time, he creates reproductions of Greek masterpieces in chalk and is an acrobatic aircraft pilot. You can read more about his work at DesignSingularity.

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