Visual Interfaces: Moving from Paper to Large-Screen Visual Display Units to Small-Screen Visual Display Units

Lawrence E. Burgee

Towson University 8000 York Road Towson, Maryland 21252-0001, USA [email protected]

Abstract

This research paper serves as a literature review on visual interfaces as we move from paper to large-screen visual display units to increasingly popular and functional small-screen visual display units. For more than 600 years, paper has been the predominant visual interface used when completing information retrieval tasks. Paper use is deeply rooted in our culture and has had a profound impact on the development of modern-day society. Visual display units gained wide acceptance in the 1970s and are the predominant user interface for computer systems. When visual display units became popular in business environments during the early 1980s, it was found that replacing paper documents with visual display units does not adversely affect the comfort and morale of office workers. However, current computer screens lead to a reading speed that is approximately 25% slower than reading from paper. Many new wireless personal digital assistants and cellular telephones have Internet connections and Web browsers that allow users to undertake information retrieval tasks using small-screen visual display units. Wireless and lightweight handheld devices with small-screen visual display units are becoming more popular as the quality and readability of the screens approach the brightness, resolution, and contrast of paper.

1 Introduction

This paper examines the evolution of visual interfaces from the introduction of paper several hundred years ago up to today’s electronic visual display units. This research paper serves as a literature review on visual interfaces as we move from paper to large-screen visual display units to increasingly popular and functional small-screen visual display units.

2 The Paper Interface

For more than 600 years, paper has been the predominant visual interface used when completing information retrieval tasks (particularly reading tasks). Paper is inexpensive, familiar to users, easy to load with content via a printer, easy to copy, distribute, and secure (physical lock-up), and the content has a very high resolution, typically 600 dots (pixels) per inch or greater. Thousands of years prior to paper, Egyptians wrote hieroglyphics on papyrus, the Chinese mastered landscape painting (incorporating symbolic text), and the Greeks painted text and graphics stories on vases and other materials (Bolter, 1993).

There are several drawbacks to using paper in today’s information-based environment. It is a fixed and passive medium where contents cannot be easily manipulated by hand or processed by machine. It cannot easily be used to take advantage of modern methods for manipulating, distributing, filing, and processing information such as that which can be done by computer application software and Internet connectivity. The speed of distributing paper- based documents is extremely slow when compared with eMail and Web-based document publication in which documents can be seen around the world within seconds of being placed on Web sites. The use of scanners and fax machines is declining as more documents are stored and distributed in electronic formats (Johnson, Jellinek, Klotz Jr., Rao, & Card, 1993).

Despite the disadvantages, paper use is deeply rooted in our culture and has had a profound impact on the development of modern-day society. Strassmann contends that paper-based documents will survive as long as institutions deeply rooted in traditions of an agricultural society continue to operate (Strassmann, 1985). Business professionals spend about 60 percent of their time handling the vast quantity of paper flowing into their office daily (Warnock, 1991). However, paper remains the most popular document medium and is likely to remain so for some time (Plume, 1988) because of its credibility (“put it in writing”), tangibility, ease of handling, portability, and compatibility will all imaging devices, such as fax machines, copiers, printers, and scanners (Lui & Stork, 2000). Paper has several physical and visual features which provide context and reference points for the pieces of text that help in the understanding of the text (O'Hara, 1996).

There are social implications to the heavy use of paper in today’s world. As we move to an environment where more people read from digital screens, those who expect new technologies to immediately change how we function often forget to take into account the social-material complex of which technologies are only a part of (Williams, 1974). Emerging technologies can solve problems, but they also create dilemmas involving social, cultural, organizational, and human factors (McKnight, 1997; Olsen, 1994). Despite the enormous popularity of personal digital assistants (PDAs) and mobile computing technology, paper usage in the U.S. continues to increase (Schilit, Golovchinsky, & Price, 1998). Of total paper production, the percentage of paper used for printing and writing increased by 13% from 1970-1997. Almost 94% of all business information is still recorded on paper, with an estimated 2.4 billion new sheets placed in paper file folders daily. Sales of paper books continues to grow and library circulation continues to increase, suggesting that people still rely heavily on paper for much of their reading activities.

A shift is occurring from print-copy-distribute to distribute-view-print along with a shift from centralized to decentralized printing. In one study Olsen found that 63% of those interviewed preferred to annotate or underline articles as they read them (Olsen, 1994). Many readers are not comfortable reading long documents on a screen. One cannot spread out pages of a large document while reading. The long-standing practice of maintaining file folders of printed materials, arranged by topic, remains popular in the electronic age (Lui & Stork, 2000).

One of the crucial properties of paper documents is fixity. Fixity refers to the fact that once a document is printed on paper it cannot be changed unless replaced by an updated version. A printed book remains the same from the publishing date into the distant future, but much of what we view on Web pages changes almost daily. Paper is stable, permanent, static, inactive, and rigid, while digital documents are characterized as unstable, impermanent, dynamic, active (interactive), and fluid (malleable and changeable) (Levy, 1994). Bolter contends that we are moving progressively from the fixed world of paper to the fluid world of digital documents (Bolter, 1991). Digital documents, particularly Web pages, lack stability of text as well as the tactile and visual cues available with paper- based documents. This affects the ability to manipulate a digital document and to develop a sense of text, which is important not only for navigation but also for comprehension (O'Hara, 1996). By sense of text we mean the feeling a user may have that he/she has a good grasp of the structural and logical arrangement of the text, which can be enhanced by fixity (Hansen, 1988). With respect to paper documents, Colley supports global coherence in that a text must have a consistent theme and be structured in a sensible sequence (Colley, 1987).

3 Large-Screen Visual Display Units

The visual display unit (VDU) is defined as the visible and usable area of a visual medium. Various synonyms for VDU appear in the literature such as cathode ray tube (CRT), visual/video display terminal (VDT), computer screen, etc. (Mills & Weldon, 1987). Vision is the most important of the five senses and VDUs are a critical component in a human-computer interface (Faulkner, 1998). Most users are not concerned with the technological aspects and underlying architecture of computer systems (particularly in the age of the Internet) and to them what they see on the VDU "is" the system (Norman, 1986). For this review, VDU will mean “large-screen visual display unit”, which in general would refer to a screen having a diagonal measure of 10 inches or greater.

The CRT has been the dominant technology for many years. A stream of electrons is emitted from an electronic gun and focused and deflected by an electric field onto a phosphor-coated screen which glows at the point of contact with the electrons (Foley & Van Dam, 1982). Flat-panel displays are smaller in form than CRTs and are typically liquid-crystal displays (LCDs), plasma panels, or electroluminescence devices (Downton, 1991). VDUs gained wide acceptance in the 1970s and are the predominant user interface for computer systems (Shneiderman, 1998). Substantial technological developments with computers and VDUs during the 1970s led to the prediction of a paperless society with in a short period of time (Lancaster, 1978) which has not come to fruition. VDUs have matured from the initial low-resolution black and white displays to today’s larger and somewhat higher- resolution color displays. Newer displays are also available in a wide range of screen sizes and formats. Due to tremendous price reductions and advancing technology over the past few years, flat-panel LCD monitors have now become more popular then CRT displays and account for the majority of monitor sales (Greenemeier, 2003). The big advantage of LCD monitors over CRT monitors comes from their greatly reduced size. LCDs also are preferred to CRTs because they reduce eye strain in that they do not flicker like CRTs. CRTs are “painted” hundreds of times per second in a process known as refresh. Human eyes can detect flicker in larger CRTs with slow refresh rates and this can bring on headaches and fatigue (Thompson, 1984).

When VDUs became popular in business environments during the early 1980s, it was found that replacing paper documents with VDUs does not adversely affect the comfort and morale of office workers (Starr, Thompson, & Shute, 1982). However, current computer screens lead to a reading speed that is approximately 25% slower than reading from paper. In today’s Web environment, the reduced reading speed on VDUs can be partially compensated by good hypertext design that allows the user to read less information and to find it faster. When users need to spend an extended period of time reading long texts, they often decide to print them out rather than read them on a VDU (Nielsen, 1996).

Electronic paper is an emerging visual display technology being developed by scientists at Philips Research. These ultrathin, flexible electronic displays combine the desirable viewing characteristics of conventional printed paper with the ability to control the displayed information electronically which can be updated as needed. Early prototypes were very slow in refreshing the screen and were restricted to the maximum speed of electrophoretic capsulized particles. Electrowetting is a new technology that facilitates the rapid manipulation of liquid-electric pixels. It utilizes voltage-controlled movement of colored film adjacent to a white substrate. The reflectivity and contrast of electrowetting produces electronic paper that is four times brighter than reflective liquid-crystal displays (Hayes & Feenstra, 2003). Scientists in this field are also developing wearable computer screens and smart identity cards that can benefit from thin and flexible visual displays (Chen et al., 2003).

4 Small-Screen Visual Display Units

Users are increasingly being exposed to VDUs that differ in size. Advancing technology is fueling the development of non-standard or alternative formats for VDUs. Since the mid-1990s, PDAs have grown in popularity for both personal and organizational access to information. New wireless PDAs have Internet connections and Web browsers that allow users to undertake information retrieval tasks using small-screen VDUs (SVDUs). Web-enabled cellular telephones, pagers, and wristwatches are increasingly being equipped with SVDUs. SVDUs are typically less then 2.5 inches wide by 2.5 inches high and have a total screen resolution of 300 pixels or less (Bjork et al., 1999). By 2004 it is expected that there will be more than one billion SVDU-equipped cellphones in use throughout the world (Bjork et al., 1999).

Wireless and lightweight handheld devices with SVDUs are becoming more popular as the quality and readability of the screens approach the brightness, resolution, and contrast of paper (Adler, Gujar, Harrison, O'Hara, & Sellen, 1998). Handheld electronic book (eBook) readers, small PDA-like devices that store entire books in a book-like structure, are gaining in popularity as technology allows for improved resolution (Lemken, 1999). Small devices are gaining in popularity (particularly as opposed to laptop computers) because they are compact, convenient to carry, easy to conceal, and consume very little power (Gessler & Kotulla, 1995). Additionally, they are boot-less (operating system always on), do not require a bulky keyboard (most have a touch-screen and a finger or pen can act as a pointing device), and can be used just about anywhere (Buchanan et al., 2001). Devices that use SVDUs typically use the full screen for applications and further segmentation (such as "windows") is not common due to the already reduced (and usually sub-optimal) screen size.

Much of the foundation of modern personal computing was laid out in the early 1970s when Alan Kay at Xerox PARC designed the Dynabook. The name Dynabook suggested that it would be portable, like a book, but have the abilities to store and manipulate data. These ideas evolved into the first commercially available portable computer, the Osborne 1 (Press, 1992). The device’s screen was small with resolution much lower than today’s commercially available PDAs.

Much of the development of today’s PDAs comes from the Computer Science Laboratory (CSL) at Xerox PARC. Beginning in 1988, CSL developed three devices aimed at eventual ubiquitous computing environments. One of the devices, the ParcTab, was palm-sized, designed to be carried at all times, and resembled today’s Palm Pilots and Pocket PCs (Abowd & Mynatt, 2000; Weiser, 1993). Ubiquitous computing enhances computer use by making computers available through the physical environment, while making them effectively invisible to the user. Anthropology studies have reported that people primarily work in a world of shared situations and unexamined and unrefined technological skills. Computers too often remain the focus of attention when in fact they should be disappearing from our awareness (Weiser, 1993). Reducing the size of computers and increasing the use of SVDUs effectively minimizes the disruptive footprint of computer technology.

In 1989, Atari introduced the Portfolio handheld computer. It used MS-DOS, was rather large by today’s standards, and had only agenda and note-taking functions, as well as some computer-like functions. In 1990, HP sold a calculator, which had some agenda functions. Several Japanese companies developed electronic organizers, such as the Casio BOSS and Sharp Wizard. These devices were small but had tiny keyboards, very small screens, and very limited memory. They generally contained address book, calendar, and memo/note-taking applications. Apple Computer released the first commercial PDA in 1993 called the Newton. It had an acceptable-quality screen but incorporated a crude version of handwriting recognition that was responsible for generally poor sales (Van Wegberg, 1998).

Palm Incorporated released the first Palm Pilot in 1996. This highly successful device sold more than 1 million units in 1997 and dominated the market with a 63 percent share. The black and white screen was highly readable and the handwriting recognition was vastly improved compared with the earlier Newton devices (Van Wegberg, 1998). This very usable device brought small-screen technology to the mainstream of computing, a trend that contains today.

There are currently many manufacturers of PDAs and sales for 2001 were more than 13 million units. There are two competing and functionally-equivalent operating systems used in PDAs: The Palm Operating System and Microsoft’s Pocket PC (formerly called Windows CE) Operating System. Devices based on the Microsoft system can usually support higher screen resolutions than the Palm devices (Akervall & Granath, 2002).

The size of the screen dictates how much information is appropriate for the available screen area (Smith & Mosier, 1986). For SVDUs, it usually is imperative to restrict the number of things displayed at once. A cluttered screen is difficult to interpret because it is a lot for the brain to process (Shneiderman, 1998). Too much clutter can be irritating because the user is burdened with information that must be filtered in order to make reasonable choices about how to complete an information retrieval task (Faulkner, 1998). Researchers have been studying the effect of display size on reading in order to determine the optimum size (Aghnami, 1998). SVDUs limit information for the reader in terms of context available around each text element within a document (O'Hara, 1996).

Displays found on modern PDAs can only display 10-15 short lines of text. As most Web content is designed for 15” and larger displays with at least 800x600 pixels of resolution, displaying full-sized pages on small devices results in substantial scrolling by the user. People using handheld computers will benefit from Web content designed specifically for their particular devices. However, it seems unlikely that all new content, let alone existing content, will be customized in this way (Trevor, Hilbert, Schilit, & Koh, 2001).

It is difficult to read long texts on small screens due to the limited screen space. Current PDAs do not adapt for reading long texts on small screens. This results in decreased readability due to frequent paging, improper margins (left/right scrolling), inappropriate line widths and awkward justification (Goldstein, Oquist, & Bjork, 2002). Rapid Serial Visual Presentation (RSVP) is a technique of showing small amounts of text on one row and then replacing it with new text after a given time period (Castelhano & Muter, 2001). RSVP has been tested in the laboratory to limited success (Russell & Chaparro, 2001).

A computer can hold many books and documents relieving the user from carrying too many things around. When using a computer it is usually possible to print out text and read documents on paper, but this is often not possible with handheld devices. You typically use them in a mobile or space-constrained environment and do not have the luxury of carrying around a printer. Unfortunately, the presentation of information is optimized for VDUs and not for SVDUs (Akervall & Granath, 2002).

Often times needed information is online, but it cannot be accessed because the user is not near a computer or does not wish to interrupt the flow of a task or conversation. PDAs with wireless Web connections are an appropriate medium for ad hoc information needs. Buyukkokten introduced five methods for summarizing parts of Web pages on handheld devices (PDAs and cellphones). His team developed special information retrieval techniques optimized for SVDUs on PDAs. The study reports on an experiment with 15 subjects and 5 treatments in which participants complete single-page information search using each method (within-subjects design). The overall findings of the study are that PDA access to the Web is a continuing problem for users. The small screen makes Web pages difficult to navigate and comprehend. A combination of keyword extraction and text summarization gives the best performance for discovery tasks on Web pages (Buyukkokten, Garcia-Molina, & Paepcke, 2001).

Much needed information is generated in mobile environments such as while driving, shopping, and conducting personal or business interactions. Frequently, we know that the information we need is online, but we cannot access it, because we are not near our desk, or do not wish to interrupt the flow of conversation and events around us. PDAs are in principle an appropriate medium for fulfilling such information needs right when they arise. PDA access to the Web continues to pose difficulties for users (Jones, Marsden, Mohd-Nasir, Boone, & Buchanan, 1999). The small screen quickly renders Web pages confusing and cumbersome to peruse. One solution to the problem is the creation of special Web pages for small devices. Such pages would be laid out for optimal viewing on small screens. Another approach has been the automatic miniaturization of standard HTML pages. Instead of displaying an entire page, only the hyperlink anchors of pages are displayed by default. The user can view the summarized set of links and drill down into the Web page (Buyukkokten, Kaljuvee, Garcia-Molina, Paepcke, & Winograd, 2002). However, compressing or filtering information could reach a point where it distorts the meaning of the information. How can the writer show the complex relationships often inherent in the information when summarization and/or filtering lead to overly small chunks of information that can disrupt the user’s ability to see the intended relationships (Kim & Albers, 2001)? Taylor alerts us that “simplistic calls to trim information” should be viewed with suspicion (Taylor, 1997).

In general, most mobile PDA-based Internet systems are difficult to use and lack flexibility and robustness (Buchanan et al., 2001). PDAs can be carried everywhere and can provide valuable mobile information via browsers in hospitals, libraries, offices, and other business settings. Gessler and Kotulla discuss at length the advantages and disadvantages of PDAs as mobile Web browsers (Gessler & Kotulla, 1995). Small screen size and short battery life for PDAs are persistent problems reported frequently in the literature. Users of SVDUs follow browser hyperlinks less frequently than larger VDUs and the success rate (in finding the desired information) is lower (Buyukkokten, Garcia-Molina, Paepcke, & Winograd, 2000).

Recent years have shown an explosion of interest in handheld computing devices such as PDAs. Their small form factor has the advantages of portability, low power consumption, and instant-on responsiveness, but also limits the size of the display. A key limitation of these devices is the user’s inability to view and interact with a large amount of information at once. Various scrolling methods can be slow for navigating long documents. Scrolling or dragging to pan the view is disruptive because it forces users to interrupt the current pen interaction, divert their attention to the scrolling maneuver and then switch back

One way to provide access to more information is to track the position of the display so it can be physically moved around to see different parts of a large workspace (Fitzmaurice, 1993). The information is spread out on a flat virtual workspace larger than the display, and the display shows a movable window (or “peephole”) on the space (Yee, 2003). Researchers have recently created a device that turns the small screen of a handheld computer into a movable keyhole. The screen is a window onto a larger virtual document. This idea relates to the concept of virtual fixity in which the user has a personal information space that can be relatively fixed. For example, a user could turn on the handheld computer and find the calendar always located on the right and Web browser always on the left (Patch, 2003). Each user can define a unique and customized virtual work space.

The dream of electronic books has been with us since Vannevar Bush published the famous article, “As We May Think,” in which he speculated on a desk-sized machine that would hold one’s personal writing and library (Bush, 1945). Van Dam developed the first fully functional eBook prototypes at Brown University in the mid-1980s (Van Dam, 1988). These prototypes used colorful dynamic graphics and three-dimensional animation. Commercial eBooks have appeared on the market over the past five years to limited appeal. These mobile devices are slightly larger than PDAs, have slightly higher resolution screens, and are designed to mimic paper-based books complete with functions for paging and moving in a sequential order, and are mobile and light weight like a book. However, they suffer from poor usability and use proprietary software which is generally cumbersome to use. They are very limited in functionality and it is debatable as to whether they offer any advantages over hardcopy books (Lemken, 1999). Screen technology has not improved as quickly as electronics or storage. Moore’s Law has not held for improvements in pixel density, contrast, power consumption, and so forth, but costs are falling. Additionally, there is no standard size for eBooks and this creates problems for publishers and developers. If after 500 years society has not adopted a standard page size for paper books, there probably is no optimal screen size for electronic books (Press, 2000).

5 Conclusions

The paper interface is deeply ingrained in our culture and society. Its static display presents both benefits and drawbacks. The introduction of the personal computer in the 1980s ushered in the era of the large-screen visual display unit. Small-screen visual display units are now found on handheld devices such as personal digital assistants and cellular telephones. A diverse range of interfaces are now available in different sizes and formats and the appropriate interface can be selected depending upon the desired application. This research paper serves as a literature review on visual interfaces as we move from paper to large-screen visual display units to increasingly popular and functional small-screen visual display units.

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