How To Design A Computer Game

Transcription

1 Take a Load Off: Cognitive Considerations for Game Design C hris Lawrence School of Design, Communication & IT University of Newcastle Callaghan, NSW, Australia 2308 chris.lawrence@newcastle.edu.au ABSTRACT As the quest for designing and developing exciting and engaging computer games continues, one must cast a thought towards what it is that makes such entertainment engaging, or indeed, disengaging. One might be of the mind that an interesting and captivating computer game would be one that evoked a high level of thought activity and concentration. On the other hand, it could be argued that if the player of a game is bombarded with instructions, information, tasks and decisions, the result is a confusing, stressful and generally unpleasant experience. To avoid giving our gaming audiences mind indigestion, some sort of strategy must be employed to facilitate an acceptable supply of cognitive stimulation. This article uses cognitive load theory to explore and discuss a number of considerations and possible tactics in presenting and organising complexity in a computer game. General Terms Design, Human Factors, Theory. Keywords Cognition, cognitive load theory, computer games, graphics, design, interface. 1. INTRODUCTION 1.1 Metacognitive Priorities For many years, the disciplines of education, psychology and instructional design have sought to understand the capabilities and limitations of the human brain in an effort to develop new strategies that would streamline, amplify or stimulate the learning process. Likewise, industries concerned with visual communication, marketing and entertainment have been making efforts to learn how consumers and audiences think with the aim of finding more effective and efficient ways of building awareness, gaining attention and altering perceptions. In the case of knowledge acquisition in an educational or learning context, a strong emphasis is placed on the need for a deeper level of thinking or metacognition. Although the ability to evoke a concentrated level of thought might be a desirable quality for material produced for the purposes of advertising or entertainment, it is not rated as an essential ingredient. More common approaches for promoting information familiarity tend to lean on that of conditioning, repetition and association instead. It could also be said that the elements of entertainment and aesthetic pleasure are often desirable for educational and instructional material but not necessarily of high priority - whereas for graphic design and entertainment it is arguably critical. In discerning the different primary objectives that these two areas have in communicating their respective messages, it would seem beneficial to explore how the research conducted by one discipline could be applied to the other. In this paper, it is suggested that even though education holds metacognition as a much greater priority when communicating information than the disciplines of entertainment and visual communication do, established cognitive theories present a new way of understanding the way entertainment and visual communication operates. Specifically, this paper discusses how cognitive load theory has the potential to be adopted in the design of computer games and interfaces. 2. COGNITIVE LOAD THEORY 2.1 Definitions and Established Components The subject of cognitive load theory has a number of active contributors presenting a variety of categories, perspectives and conclusions [12]. On an elementary level, the issue that would seem to put all of this research under the one umbrella is that enquiry is based on the core notion that the human brain has a limited capacity to process information. In understanding those limitations it is commonly suggested that certain measures can be developed and employed to utilise cognitive capacity in a more optimal fashion. However, as a closer examination of cognitive load theory literature will reveal, a generally accepted underlying architecture exists as well as a number of observed effects and overload scenarios. As argued by Sweller et al. [12, 14, 15, 18], human cognitive architecture possesses two main types of memory - working memory and long-term memory. Working memory is primarily responsible for the selective processing of information gathered by our senses (such as auditory and visual) and has a very limited capacity and duration. We use our working memory to make sense of the information we receive, organising and constructing more complex concepts into what are referred to as schemas. Schemas are stored in and retrieved from our long-term memory, which unlike working memory, has a comparatively unlimited capacity. Schemas retrieved from long-term memory give us the ability to automate our learning and understanding without consuming the same amount of working memory that was expended in the creation of those schemas. The varying levels of automation that each schema provides, allows us to learn increasingly difficult and complex material. Several categories of cognitive load have also been established; intrinsic cognitive load, extraneous cognitive load and germane cognitive load [12]. Intrinsic cognitive load describes the situation whereby a concept or piece of information is by its very nature difficult to understand as all

2 the elements within it interact, and without such interaction, meaning is lost. When the development of schemas in working memory is disrupted by other incidental or irrelevant information, it is referred to as extraneous cognitive load. Germane cognitive load on the other hand, is additional cognitive load for the purpose of enhancing schema acquisition rather than interfering with it. Because extraneous cognitive load is undesirable in a learning context and is a comparatively easier problem to deal with than intrinsic cognitive load, quite a number of different strategies have been developed to reduce it and have given place to a number of observable effects. Sweller et al. [16] identified the split-attention effect as the situation whereby a statement and a diagram must be integrated using working memory in order to understand an instruction that neither the textual or pictorial components could convey independently. Split-attention occurs because there are two separate sources of information that can only be examined one at a time. While reading the text, one is unable to look at the diagram, and vice versa. The modality effect describes the utilisation of both audio and visual sensory input channels, thus effectively expanding the capacity of a working memory that is only really utilising one of the two channels. The typical example given is that of the textual component of a split-attention effect being transmitted as a spoken narration instead, freeing the visual sensory channel to focus solely on the graphical component. 2.2 Relevance to Game Design For the most part, cognitive load theory has resided in the context of learning and instructional design, but has progressively broadened in disciplinary applications in recent years. Although very little published evidence exists for its use in the design of interactive entertainment, its usefulness in such a circumstance would seem obvious. The effective learning of a computer game s controls, interface, plot, rules and general play should logically have a direct effect on how successfully a player can operate the game. One could assume that performing tasks such as prioritising game objectives, problem solving, navigating a virtual space or simply recognising the consequences of decisions and actions are beyond a player who has not gained a basic understanding of at least some of the aforementioned governing qualities of the game first. It would also seem unlikely that a person would persist in attempting to play a game that they are unable to understand or find any satisfaction playing - despite the strangely contrary evidence that can be found in the game of golf. 3. CUES AND HIGHLIGHTING 3.1 Supporting Theories In the context of multimedia learning, Mayer and Moreno [10] describe a number of scenarios involving extraneous cognitive load, and test a number of load-reducing methods. One particular scenario describes a learning situation in which a narrated animation included an excessive amount of interesting, but ultimately digressive material. One method successfully employed to reduce cognitive load in this instance was referred to as a signalling effect and involved the implementation of various audio and visual cues, directing the viewer s focus to the most critical information throughout the presentation. Some of the signalling methods used included accentuating key words in the audible narration, adding coloured arrows to indicate important images, and grouping the text and images under meaningful headings and sections. This signalling facilitated a more appropriate and concentrated process of selecting and structuring relevant information for the viewer. Focal points, visual priority and hierarchy have arguably been some of the most heavily utilised principles and techniques in the graphic design industry since it began. Bringing attention to the most vital information in a piece of visual communication first is almost always a primary consideration, particularly in a society heavily saturated in advertising, marketing and media all competing for consumer attention. The study of effectively directing a viewer s attention to a particular section of text or imagery is also known as highlighting [8] and has been explored on an empirical level by Williams [19] and Maguire [9]. Williams looked closely at textual highlighting which included attributes such as bold, italic, underlined, inversing, blinking, movement, colour-shift and typeface changes concluding that highlights such as allcaps and underlining were to be avoided in favour of a limited use of bold, italics and point-size increases. 3.2 A Possible Implementation Suppose we take the common example of a computer game that uses a cartographic visual to assist in explaining the objectives of a battle-plan that must be followed (Figure 1). In amongst the instructions for the game, a number of locations on the map are mentioned such as the starting point, a township from which to collect supplies, a number of fortresses that must be conquered, and a finishing point. Without the aid of signalling or highlighting, a split-attention effect is present, as working memory is required to integrate both the words and the picture in order to comprehend the instructions properly. A portion of working memory is diverted to searching for the map locations featured in the instructions, resulting in extraneous cognitive load. Figure 1. Example of a computer game using a battle-plan map without cues or highlighting.

3 Figure 2. Implementation of basic visual cues 4.2 A Possible Implementation To take the example of the battle-plan map once more, a cognitive load issue still resides in the interface design if the textual instructions are still being presented in a visual format. Even with a number of visual cues and signalling techniques employed, a split-attention effect remains, as the player must still divide their attention between reading the text and examining the diagram. Implementing our understanding of the modality effect, one of the obvious changes to be made in this circumstance would be to generate a spoken narrative from the textual list of instructions, which would then be broadcast and synchronised with the visual cues and signalling. In order to avoid the redundancy effect, the next modification would be to remove the written instructions, which would not only deal with the unnecessary duplication of information, but would release more screen and layout space for the display of visual components (Figure 3). By adding simple visual cues at appropriate intervals of the instructions, such as location names on the map becoming bold when mentioned, a moving, coloured trail of arrows indicating direction and location sequence plus small animations representing the events that will occur at each location, extraneous cognitive load should effectively be reduced, resulting in a better chance of the instructions being understood and followed (Figure 2). 4. AUDIBLE NARRATION AND PROMPTS 4.1 Supporting Theories Paivio et al. [13] is commonly credited with establishing the picture-superiority effect which essentially states that pictures are easier to recall than words. However, Paivio et al. and a number of others [1, 13] have also produced evidence indicating that the combination of pictures and words together are better remembered than either pictures or words alone. Words can take on a number of manifestations though written as visible text or spoken in an audible voice. As mentioned earlier, the modality effect in cognitive load theory suggests that a learner that receives verbal and graphical instructions in both audible and visual format simultaneously will generally learn more efficiently than if the same instructions were received in an all-visual format. Quite a number of experiments have been conducted over recent years [4, 11, 17] yielding a convincing body of findings supporting the modality effect, many of which stress its importance in a multimedia-training environment. Upon analysing a similar scenario, Mayer & Moreno [10] described the method of moving some of the essential processing from the visual channel to the auditory channel as off-loading. Another important conclusion drawn by Mayer & Moreno, and supported by the work of Leahy et al. [7], is that there is credibility in what is referred to as the redundancy effect. This effect is a reference to the cognitive load induced by the presence of non-essential or unnecessary information particularly content duplication. It was noted that in the case of having an audible narration accompanied by a visual text of identical content, learners were reported as not performing as well as when an auditory narration was the only word-based transmission present. Figure 3. Removal of redundant information 5. PROGRESSIVE DISCLOSURE AND USER EXPERIENCE 5.1 Supporting Theories In the late 1990s, a number of cognitive load theorists began concentrating on an observable phenomenon now known as the expertise reversal effect [3], whereby some of the methods developed to reduce cognitive load, appeared to have a lesser effect, and eventually an adverse effect, on learners who were considered to have obtained a high level of familiarity or experience with the general subject matter being presented. In a typical example of a split-attention effect, Kalyuga et al. [6] demonstrated that the text components of an instructional presentation eventually became redundant material for a learner with a high level of expertise, making a presentation of the same material without the text a preferable alternative. This would seem to support established cognitive architecture in that with every schema learned and developed, an appropriate ability to automate learning is also gained. So, as a novice develops into an expert, less cognitive effort is required to understand new material, therefore less information and

4 instruction is required in order to lead them to that level of understanding. The accommodations made in instructional designs for this progressive reduction in instructor control and increase in learner control has earned the description of being a fading technique. A technique that would seem to parallel that of fading is progressive disclosure which was a recognised presentation tactic from early complex digital interfaces [5]. Another method for preventing an overload of information, progressive disclosure involves revealing only immediately relevant or requested sections of information at a time. A common example of this technique can be seen in drop-down menus or advanced search interfaces within software and website designs. Such a structure means that the more infrequently used or less relevant sections of information remain concealed until needed or appropriate. Although this is not a technique necessarily designed to facilitate germane cognitive load (like fading is), it does offer a method of reducing extraneous cognitive load while offering flexible control over the level of a system s complexity (or at least perceived complexity). On a multi-disciplinary front, the law of parsimony, or Occam s Razor [2] would similarly support the reduction of unnecessary elements in a design or system to achieve maximum simplicity so long as its functionality was not drastically compromised. In an entertainment context, progressive disclosure can also be used as a method of enticing a person to explore a system. One very simple example would be that of a season of thrilling television episodes, where each episode progressively discloses interesting information about the characters and the underlying plot without giving away the entire story in all of its complicated glory. Similarly, many theme park rides have a built environment for the line-up that not only obscures the length of the queue from would-be riders, but progressively discloses sensory stimulus about the ride while they wait, for example, video footage, sound effects and ride attendants in character. 5.2 A Possible Implementation Let us assume that our hypothetical battle-themed computer game has a very detailed level of control over how an army or group of battle units behave. Techniques and strategies such as attack formations, defensive and aggressive modes, patrol routes and a number of other functions all require a control of some sort in the game s design. To display a button on screen for each of these controls is likely to cause a little confusion and disorientation for a player who is unfamiliar with this style of game let alone this game in particular. In light of fading and progressive disclosure techniques, a way of catering to the novice user of the game would be to have any of the less-critical controls that could otherwise be automated, remain hidden or grouped under a small number of generic controls. As the difficulty of the game increases with every level or scenario, the deeper-level controls could be made active. Alternatively, the player of the game could be given the ability to toggle between the complete set of controls and the simplified set of controls depending on their familiarity with the game (Figure 4). Figure 4. Example of progressive disclosure used in a set of game controls 6. CONCLUSION From the research that has been conducted within cognitive load theory and the other related areas discussed in this paper, it would seem that the computer game designer has a number of considerations to make when planning to present a product with a level of complexity. In learning how to operate a game or follow a game s instructions, extraneous cognitive load is a significant factor and can be minimised by applying tested instructional design techniques and theories. The appropriate implementation of visual cues, signalling and highlighting offer relief in the case of a split-attention effect. The balancing of audio and visual input channels, or off-loading, would appear to be a feasible strategy in making a complex game instruction much more intelligible. It would also seem possible that game controls and scenario complexity can be made dynamic and flexible through the utilisation of fading techniques and progressive disclosure. The theories and principles discussed here seem to have the potential to be applied to game design and interactive entertainment in a constructive manner and further investigation of its application by the designers of such material would be very interesting. 7. REFERENCES [1] Childers, T. R. & Houston, M. J. Conditions for a Picture Superiority Effect on Consumer Memory, Journal Of Consumer Research, 11, 1984, [2] Domingos, P. The Role of Occam's Razor in Knowledge Discovery, Data Mining and Knowledge Discovery, 3(4), 1999, [3] Jeroen, J. G., van Merriënboer, J. J. G. & Sweller, J. Cognitive Load Theory and Complex Learning: Recent Developments and Future Directions. Educational Psychology Review, 17(2), 2005, [4] Jeung, H. J., Chandler, P., & Sweller, J. The role of visual indicators in dual sensory mode instruction. Educational Psychology, 17, 1997,

5 [5] Johnson, J., Roberts, T. L., Verplank, W., Smith, D. C., Irby, C., Beard, M. & Mackey, K. The Xerox Star: A Retrospective. Computer, 22(9), 1989, [6] Kalyuga, S., Chandler, P. & Sweller, J. Levels of expertise and instructional design. Human Factors, 40(1), 1998, [7] Leahy, W., Chandler, P. & Sweller, J. When Auditory Presentations Should and Should not be a Component of Multimedia Instruction. Applied Cognitive Psychology, 17, 2003, [8] Lidwell, W., Holden, K. & Butler, J. Universal Principles of Design: A Cross-Disciplinary Reference. Rockport Publishers Inc. Massachusetts, USA [9] Maguire, M. A Review of Human Factors Guidelines and Techniques for the Design of Graphical Human-Computer Interfaces, International Journal of Man-Machine Studies, 16(3), [10] Mayer, R. E. & Moreno, R. Nine Ways to Reduce Cognitive Load in Multimedia. Educational Psychologist, 38(1), 2003, [11] Mousavi, S., Low, R., & Sweller, J. Reducing cognitive load by mixing auditory and visual presentation modes. Journal of Educational Psychology, 87, 1995, [12] Paas, F., Renkl, A. & Sweller, J. Cognitive Load Theory and Instructional Design: Recent Developments. Educational Psychologist, 38(1), 2003, 1-4. [13] Paivio, A., Rogers, T. B. & Smythe, P. C. Why Are Pictures Easier to Recall than Words? Psychonomic Sciences, vol. 11(4), 1968, [14] Sweller, J. Instructional design in technical areas. Camberwell, Australia: ACER Press, [15] Sweller, J. Visualisation and Instructional Design, In Proceedings of the International Workshop on Dynamic Visualizations and Learning (Tübingen, Germany, July 18-19, 2002). Knowledge Media Research Center, Tübingen, 2002, [16] Sweller, J., van Merriënboer, J. J. G., Paas, F. Cognitive Architecture and Instructional Design. Educational Psychology Reveiw, 10(3), (Sep. 1998), [17] Tindall-Ford, S., Chandler, P. & Sweller, J. When Two Sensory Modes Are Better Than One. Journal of Experimental Psychology: Applied, 3(4), [18] van Merriënboer, J. J. G., & Sweller, J. Cognitive Load Theory and Complex Learning: Recent Developments and Future Directions. Educational Psychology Reveiw, 17(2), (June 2005), [19] Willams, R. The Mac is Not a Typewriter, Peachpit Press, 1990.