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Collocating Interface Objects: Zooming into Maps Jon May Tim Gamble School of Psychology Department of Psychology University of Plymouth University of Bath Plymouth, PL4 8AA, UK Bath, BA2 7AY, UK [email protected] [email protected] ABSTRACT Such flexibility comes at a cost, however, because the May, Dean and Barnard [11] used a theoretically based representation on the device cannot necessarily be the same model to argue that objects in a wide range of interfaces as that on a paper map. A paper map is a designed should be collocated following screen changes such as a representation of reality. It has been constructed by a skilled zoom-in to detail. Many existing online maps do not follow practitioner to take advantage of the map readers’ attentional this principle, but move a clicked point to the centre of the and perceptual processing, to allow them to selectively subsequent display, leaving the user looking at an unrelated attend to certain classes of information in alternation [4]. location. This paper presents three experiments showing that Enormously successful, cartographic conventions have not collocating the point clicked on a map so that the detailed developed overnight, and their evolution has relied upon location appears in the place previously occupied by the developments in printing technology as well as the skill of overview location makes the map easier to use, reducing eye the cartographer. In moving from a static, paper to dynamic, movements and interaction duration. We discuss the benefit electronic representations, with far smaller screens and lower of basing design principles on theoretical models so that they resolutions than are achievable in print, cartography faces a can be applied to novel situations, and so designers can infer challenge. Allowing classes of information to be hidden or when to use and not use them. revealed adds interactional overheads to the design and use Author Keywords of a map that are absent when the map design takes Zooming; collocation; maps; cinematography; eye-tracking; advantage of selective attention. Changing between different cognitive models. scales of map as the user zooms in and out requires design decisions to be made about how successive views should be ACM Classification Keywords related. Designing an interactive map becomes a problem in H.5.2. User Interfaces: Theory and methods human-computer interaction, prone to the same conflicting INTRODUCTION demands as other computer interface designs [5]. Interactive maps are everywhere nowadays, and map use has Technological change makes trade-offs between speed, become routine [5]. Ramblers and drivers no longer have to capacity and mode of delivery difficult to anticipate. battle with unwieldy sheets of paper, compromising breadth Fashions in implementation flourish and designers imitate of representation against level of detail, with the crucial more often than they innovate. junction lost in the fold of the map, and the new road not One thing that does not change, however, is the mental even shown. Up to date cartographical information is now architecture of the map reader. It has previously been argued instantly accessible on computers, cars and handheld devices [2] that computer interface design should be a science as that are wirelessly connected to the internet, accurately much as a craft, and should benefit by a principled positioned by GPS [9]. Relevant objects or businesses can be understanding of the tasks users undertake, in order to highlighted and irrelevant detail removed from the view, and capitalise upon the mental resources available for interaction. the maps can be drawn at whatever level of detail the user Early in the development of computer based maps, requires for their current goal, zooming in from a low detail Moellering noted that ‘when one begins to work with overview to successively more detailed local views of an interactive display systems and particularly animations ... area [3]. displays must be considered in a dynamic setting’ [12]. Some researchers (for example, Young and Clanton [17]) have Permission to make digital or hard copies of all or part of this work for since advocated that interface designers learn from the personal or classroom use is granted without fee provided that copies are dynamics of film editing, and should manage changes in their not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for interfaces in the same way that film editors manipulated components of this work owned by others than ACM must be honored. temporal and spatial jumps in films. May and Barnard [10] Abstracting with credit is permitted. To copy otherwise, or republish, to argued that rather than naively imitate cinematographic post on servers or to redistribute to lists, requires prior specific permission editing conventions, designers needed to understand why and/or a fee. Request permissions from [email protected]. CHI 2014, April 26 - May 01 2014, Toronto, ON, Canada these conventions worked for films, and to create parallel Copyright 2014 ACM 978-1-4503-2473-1/14/04…$15.00. changes in their interfaces based upon that understanding. http://dx.doi.org/10.1145/2556288.2557279 Film editing had evolved as a craft skill, and its rules of thumb were situated within the domain of camera angles, lighting, and narrative, as sets of ‘dos and don’ts’, with no One problem with the theoretically based principle of real account of why certain practices worked and were collocation was that there was no empirical evidence that ‘filmic’, while others were ‘unfilmic’. While the work of filmmakers actually did make use of it. May, Dean and researchers such as Kraft [6,7] had shown that conventions Barnard [11] gave a more detailed account of the cognitive in film cutting did have a sound psychological basis, their model of film watching, and reported an eye-tracking study domain specific nature made it hard for designers to know in which participants watched a commercially released film what it was they were to apply to their interfaces. in its entirety. They measured the amount that observers moved their gaze location in the frames immediately after May and Barnard [10] presented a theoretical analysis of each of ten classes of cuts, and found that there was minimal cinematography based upon Barnard’s Interacting Cognitive eye movement in cuts where the cut zoomed-in to a detail, Subsystems (ICS) model of cognition [1], and made several followed a moving actor or object, showed objects whose extrapolations to interface design, including one scenario of position was predictable, or showed the result or a tourist information system combining large-scale and consequence of an action, or showed novel unexpected detailed views of a locale to help people find places of objects. In all of these circumstances, filmmakers had interest and plan routes. The problem posed was how to succeeded in collocating salient regions of the screen before combine these two representations. In contrast to ingenious and after cuts, so that the viewers did not have to move their and novel combinations of fish-eye views, magnifying lenses eyes to locate something on the screen to comprehend the and multiple simultaneous displays, it was argued that to be unfolding narrative. In five other classes of cut, large eye like a film the map interface should cut directly from an movements were found. Based on these findings, May et al. overview to a detailed view, without any swooping specifically argued that map interfaces should make use of animation (as advocated in the context of data spaces by collocation when zooming in and out to help map users Mackinlay, Card and Robertson [8]). rapidly locate the topic of their enquiry without having to The cognitive model of film watching that was proposed search the screen for it. They also made recommendations assumed that the main task of someone watching a film was about interactions where collocation would not be necessary, to follow the narrative (in ICS terms, at the propositional and but where structural changes in the display might guide a implicational levels of representation), and that any user to the novel information, while leaving previous requirement imposed upon them to search the screen for information visible to provide a context or history of the relevant material (in ICS terms, at the object and interaction. Such a situation, where translation would be propositional levels of representation) interfered with this better than collocation, might arise in the use of hierarchical task, detracting from their immersion in the story and making databases, for example, where an object or name makes them aware of the surface detail at the expense of the story. sense in the context of superordinate information and might Similarly, it was argued that in using a computer interface to be ambiguous or difficult to parse without this context carry out a task, any requirement for users to search the remaining on the screen. screen to relocate elements following a scene change would Despite this research, the translation convention was interfere with their main task, making the system less usable. subsequently adopted for several computer-based maps, and Subsequent work on task-switching [13] makes a similar in a recent evaluation of map interfaces, colocation was not point, that interleaving two tasks adds cognitive overheads in even considered as an option [16]. There are clearly reasons terms of time