desktop virtual environments: a study of navigation and age

Desktop virtual environments: a study

of navigation and age

H. Sayers*

School of Computing and Intelligent Systems, University of Ulster, Magee Campus, Londonderry BT48 7JL, UK

Received 6 February 2004; revised 4 May 2004; accepted 13 May 2004

Available online 2 July 2004

Abstract

Navigation in virtual environments on desktop systems is known to be problematic. Research into

the usability of the tools presented on two-dimensional interfaces indicates that, for even relatively

simple tasks, users experience some degree of frustration. As the user community broadens with an

increasing range of applications and services making use of three-dimensional presentation, the

usability of these interfaces becomes ever more important. In this paper, we describe the results of an

experiment performed to evaluate the usability of a number of visual navigation tools and the effect

for two age groups (18–45 and 46 þ ). Results indicate that, for both age groups, the visual

presentation of navigational aids improves navigation performance in terms of both time taken to

complete tasks, and user satisfaction with the system. In all experimental conditions younger

participants achieved better performance times, although the gap between the groups decreased

when a choice of navigation aids was presented.

q 2004 Elsevier B.V. All rights reserved.

Keywords: Desktop virtual environments; Navigation; Age; Usability

1. Introduction

A three-dimensional (3D) virtual environment (VE) is a computer representation of a

real world space or an imaginary space through which users can navigate and in which

they can interact with objects. Unlike fully immersive VEs which use specialised

interaction devices such as head-mounted displays to create a sense of presence for the

user within the 3D world, desktop systems exploit general-purpose hardware for

interaction (PC, mouse, keyboard) and although obviously offer a much reduced sense of

0953-5438/$ - see front matter q 2004 Elsevier B.V. All rights reserved.

doi:10.1016/j.intcom.2004.05.003

Interacting with Computers 16 (2004) 939–956

www.elsevier.com/locate/intcom

* Tel.: þ44-28-71375553; fax: þ44-28-71375470.

E-mail address: [email protected]

http://www.elsevier.com/locate/intcom

presence in the VE, are still useful for many application areas (Green and Jacob, 1991).

The Virtual Reality Modeling Language (VRML), commonly supported by all popular

Internet browsers, has opened up VE technology to a wide range of users using standard

desktop systems. Research has shown that existing user interface guidelines do not address

the particular requirements for interfaces to VEs, and no standard ‘look and feel’ has yet

evolved for interfaces to 3D worlds (Hand, 1997). Users of VE applications, however,

require intuitive tools to maximise their productivity. In VE applications, this need can be

defined as the need for effective navigation and interaction. There has been much research

into usability design for virtual environments themselves (Fencott, 1999; Kaur, 1998;

Kaur Deol et al., 1999; Sayers et al., 1999), but little consideration has been given to the

usability of the tools presented on interfaces to desktop VEs. There has also been little

research into the effect of age on the usability of such tools.

The population of the developed world is getting older, and the use of computers in

everyday life is becoming more prevalent and indeed more necessary. In order to avoid social

exclusion and to be able to live more independently, therefore, older adults will increasingly

need to be able to use computers and computer systems (Zajicek, 2003). Hawthorn (2000)

reports that in the United States, people over 45 years old will soon constitute over half of the

adult population. Research has shown that older users (over 60 years), although willing to

learn to use computers, consistently have more difficulty than younger people (Czaja, 1996).

As older users become increasingly exposed to computer technology, understanding their

unique requirements will become a much more important consideration in the design of

human–computer interfaces than at present, and a body of research has begun to focus on

human–computer interface design to assist interaction with two-dimensional applications

for older users (Czaja, 1996; Mead et al., 1997; Worden et al., 1997). Hawthorn (2003)

highlights the perceived changes in future older generations and computer experience (i.e.

that the number of inexperienced older users will decrease) and believes that there is a very

interesting and important research topic to be found in how today’s 40–60-year-old

computer users will adapt to changes in computing technology as they get older.

Older people are as diverse as younger people. Their exposure to computers, for

example, will vary, with many having had little or none, while younger people have grown

up with technology as an integral part of their lives. Changes in older adults’ abilities—

physical and cognitive—also vary considerably (Rogers, 1997). A one-size-fits-all design

approach is therefore inappropriate for this user group (Browne, 2000). Research has

acknowledged the importance of involving older people in the development process

(Hawthorn, 2003; Keates and Clarkson, 2002), and Eisma et al. (2003) advocate the

concept of ‘mutual inspiration’ to tackle this issue where close collaboration between

designers and older users is started at a very early stage of any development. Gregor et al.

(2002) suggest replacing the standard User Centred Design techniques which tend to rely

on quite homogeneous user groups for testing, with User Sensitive Inclusive Design which

seeks out diversity, in an effort to ensure true usability for older adults.

Initial results from research into the effect of age when navigating in 3D scenes

displayed on desktop systems points to a deterioration in performance as age increases. A

negative correlation was noted, for example, between age and navigation performance in a

study of the usability of collaborative desktop VEs, indicating that younger users

performed better than older users (Ousland and Turcato, 1999). Dalgarno and Scott

H. Sayers / Interacting with Computers 16 (2004) 939–956940

(2000), also found that, when evaluating motion control with 3D browsers, users younger

than 40 performed slightly better than older users in movement tasks, but no further

research has been done to investigate this effect more fully. This paper addresses the effect

of age on the usability of visual navigation tools for navigation in 3D scenes presented on a

two-dimensional desktop interface.

2. Navigation in virtual environments

The concepts and technologies associated with VEs mean that designing them with a user

centred approach is not as straightforward as for traditional computing applications

(Herndon et al., 1994). The third dimension introduces additional issues such as user position

within the environment, human-like navigation, viewpoint control and the exploratory

nature of the interaction. In addition, VE users have varying objectives depending on the

context of use. Users of 3D games, for instance, will have different requirements from those

interacting with a multi-dimensional information visualisation space or multiple users in a

collaborative virtual application. The key task of navigation, however, is common to all VE

application users. Navigation is the process of moving around an environment, deciding at

each step where to go (Jul and Furnas, 1997). Kaur (1998) identified navigation as the default

behaviour which users return to after other interaction tasks such as the manipulation of an

object. Significant usability problems, however, have been found to be caused by navigation

problems (Darken et al., 1998). As a result, a large body of work exists which focuses on

issues relating to 3D navigation. Several studies investigate the differences in spatial

knowledge acquired from maps and exploration (Ruddle et al., 1999; Thorndyke and

Hayes-Roth, 1982; Waller et al., 1998; Witmer et al., 1996). The need for landmarks to

support navigation in large virtual worlds has also been emphasised (Darken and Sibert,

1996; Vinson, 1999). Further research has investigated the use of novel navigation aids such

as the ‘Worlds in Miniature (WIM)’ metaphor (Stoakley et al., 1995), which provides users

with a miniature representation of the loaded environment held in the virtual hand of the user

and superimposed over a section of the environment itself. Both the WIM and the

environment can be directly manipulated. The ‘Worldlets’ technique of Elvins et al. (1998)

uses a similar approach except that there is no overlap with the presented environment—

Worldlets are 3D interactive thumbnails displayed outside the environment. Chittaro and

Scagnetto (2001) found ‘semitransparency’, where users are able to see through occluded

surfaces within the VE, to be a useful navigation aid.

2.1. Navigation problems

One of the main problems associated with navigation in VEs is the problem of

becoming lost or disoriented in the virtual world. This problem has been attributed to a

number of factors, including:

† lack of support for speed control (Mohageg et al., 1996; Rushton and Wann, 1993).

When the speed of movement is too fast, disorientation frequently occurs

(Miller, 1994). Although faster speeds may reduce time and effort over large distances,

H. Sayers / Interacting with Computers 16 (2004) 939–956 941

slower velocity has been found better in carrying out precise, intricate movements

(Johnsgard, 1994). Velocity, therefore, needs to be appropriate for the size of the scene

presented and for the tasks which have to be carried out;

† navigational modes, for example ‘walking’ and ‘flying’ (Johnsgard, 1994; Tan et al.,

2001). Even when in walk mode, users can become disoriented if movement is not

confined to a level plane (Sayers et al., 2000);

† moving either too close to (Kaur et al., 1996; Marsh and Wright, 1999) or through

virtual world objects (Marsh and Smith, 2000);

† the cognitive load placed on the navigator (Smith et al., 1999);

† the restricted field of view available on the screen (Neale, 1997);

† lack of identifiable cues (landmarks) placed within the VE itself to aid the acquisition of

spatial knowledge (Darken and Sibert, 1996);

† support for automatic navigation (teleporting) to predefined locations within the

environment (Mohageg et al., 1996). Although this has been found to be an effective

means of moving to particular locations of interest within an environment, it can serve to

increase a user’s sense of disorientation if further indicators of position within the

environment, such as a map, are not provided (Sayers et al., 2000; Tan et al., 2001).

These problems have been shown to result in low usability and user frustration (Kaur

et al., 1996; Miller, 1994). Often, much practice with a VE is required before users have

gained enough familiarity with the environment to allow for successful navigation. This is

a time-consuming process and users may not always be willing to take this time (Ruddle

et al., 1997). The presentation of visible navigational aids on the VE interface is therefore

of particular importance.

This was the main finding from a usability evaluation of current 3D browser interfaces

carried out by the authors (Sayers et al., 2000). Four categories of interface, differentiated by

their layout, were evaluated and significant usability problems were identified. Most notably

these included the issues of speed control, error correction, precise or intricate movements

and the viewing plane. Many participants in the experiments found default speeds provided

by the viewers to be too fast. Those interfaces which did allow for manipulation of speed had

no easily identifiable control presented on the interface and users were often unaware that

this facility was available, or, if they did find it, were dissatisfied with the level of control

supplied. Collisions with objects within the experimental VE were frequent and rectifying

the situation was often found to be very difficult. Users often used the facility to teleport to

predefined locations as a means of getting out of a tricky situation, but suffered consequent

disorientation. Participants frequently wanted to be able to undo particular movements yet

were unable to do this. In the performance of intricate movements, such as moving around or

behind an object within the environment, many difficulties were encountered. Both speed of

movement and error correction were factors in this problem. Participants evidently

preferred to move around the environment on a level plane as if walking in the real world and

preferred to have their movement constrained to this level.

As a result of these experimental findings, design recommendations were derived

and applied to the development of a novel interface with visual navigation aids using

the Java3D API, to enable a more thorough investigation of the usefulness of the

various navigation tools presented on interfaces to 3D worlds on desktop systems.


These recommendations and the developed interface are described in detail in Section 3

along with the design of an experiment to assess the effectiveness of the tools and the

influence of age on the results.

2.2. The effect of age

Two studies on Web navigation comparing older and younger users have found that

older users (over 55 years and over 65 years, respectively) complete navigation tasks less

successfully and more slowly than their younger counterparts (Chadwick-Diaz et al.,

2003; Meyer et al., 1997). Design modifications which help older adults have been found

to improve the performance of both older and younger users while not affecting the

difference in performance between the two age groups (Chadwick-Diaz et al., 2003;

Worden et al., 1997).

A limited amount of research exists into the effect of age on navigation in VEs.

Interaction in immersive VR systems has been found to be feasible for older users when

using a driving simulator to assess the driving capabilities of people who have suffered

head injuries (Liu et al., 1999). Ousland and Turcato (1999) identified a negative

correlation between age and navigation performance in a study of the usability of desktop

collaborative VEs, finding that younger users performed better than older users. Dalgarno

and Scott (2000), when evaluating motion control with 3D browsers on desktop systems,

found that users younger than 40 performed slightly better than older users in movement

tasks. No research has been done, however, to investigate the effect of age on navigation in

3D scenes more fully.

3. Development of the experimental interface

Seven design recommendations were derived from the authors’ earlier usability

evaluations (Sayers et al., 2000):

1. There should be little or no hidden functionality on the interface, such as specific key

presses for certain actions or having to search through a variety of menus. All tools

which provide core functionality should be visible on the interface.

2. Users should easily be able to identify how to control speed of movement within an

environment and also be able to flexibly control it. Although all the interfaces evaluated

provided for speed control, none provided a clear indication to users of how to control

speed and many users experienced frequent collisions and disorientation.

3. Since the interfaces rated most highly in the experiments provided an indication of the

direction of movement, this feature should be supported.

4. Support for natural navigation modes should be supported and defined as the default

movement mode. ‘Walk’ mode was the preferred means of movement in these usability

experiments with movement confined to a level viewing plane so that the user’s current

orientation was maintained when carrying out tasks such as turning.

5. It should be possible to reverse actions easily. An ‘undo’ facility should be supported,

promoting easy error correction.


6. A map of the VE showing the user’s position within the environment should be

accessible. All participants, when asked for recommendations to improve the

interfaces, suggested the provision of a map to aid orientation and wayfinding within

the environment.

7. In addition to supporting automatic movement to predefined locations within a loaded

environment, users should be provided with the ability to define their own locations of

interest to which they can easily teleport when necessary. This was another user

recommendation for improvement.

Fig. 1 presents the developed interface. All core functionality is presented visibly to the

user (Recommendation 1). A sliderbar allows the user to adjust the speed of movement

within the displayed environment, with the default speed set to ‘walk’ (Recommendations

2 and 4). A direction dial allows the user to view the direction of movement in terms of

North, South, East and West (Recommendation 3). The ‘Undo’ button allows users to

undo previous actions consecutively (Recommendation 5). Fig. 2 presents the ‘you-are-

here’ map superimposed on the environment in the top left-hand corner of the screen,

activated by the button labelled ‘Show Map’ (Recommendation 6). This map displays the

user’s current position within the environment. The user is unable to continue interaction

with the displayed environment until the map is closed.

A button labelled ‘Mark’ was provided in an effort to accommodate automatic

navigation whilst not adversely affecting the user’s orientation (Recommendation 7).

On clicking this button, a dialog box is activated which allows the user to type in his or

her own choice of name for the location being labelled. This name then appears on

Fig. 1. The visible tools.


the ‘My Trail’ list at the top of the toolbar, and the user can then teleport to any of these

locations automatically by double-clicking on the name (Fig. 3).

The top menubar on the interface provides the facility to display each tool individually,

all together (as in Fig. 1), or hide them from view completely through choices provided

within the ‘View’ menu.

A timer with ‘Start’, ‘Stop’, ‘Reset’ and ‘Hide’ options is also available for display

from the ‘Options’ drop-down menu, in order to eliminate the need for manual timing of

the experiment tasks.

3.1. Experiment design

A study was designed to test the effectiveness of the tools presented within this interface

and the effect of the participants’ ages on the time taken to complete navigation tasks. There

were six adaptations of the interface: the control condition had no tools presented on the

screen; the second, third, fourth and fifth interfaces each had an individual tool displayed

along with the direction dial and list of movement modes—the map, the speed control, the

mark button and the undo button, respectively; and the final condition displayed all the tools,

as shown in Fig. 1. There were two age groups used within the experiment: 18–45 and 46 þ .

This division was chosen for two reasons—firstly, findings from the research literature on the

effect of age in desktop VE navigation point to a slight deterioration in performance at the age

of 40 (Dalgarno and Scott, 2000); and secondly, due to the smaller number of older volunteers

for the study, it was necessary to use this division point (45) to ensure that each of the six

Fig. 2. Viewing the map.


interface conditions contained participants from both age groups. Two hundred and four

individuals (students from various faculties at the Magee Campus), aged between 18 and 68

and inexperienced in 3D navigation, volunteered as participants in this experiment, and were

placed into six groups of 34—one group for each test condition (see Table 1). This between-

groups division was necessary to eliminate the learning effects due to the acquisition of

navigational knowledge and experience with the navigational tools. Participants were

unevenly represented in terms of both gender and age group, with 148 females (117 aged

between 18 and 45, 31 aged 46 þ ) and 56 males (46 aged between 18 and 45, 10 aged 46 þ ).

Due to the smaller number of male participants, especially within the smaller 46 þ age

group, gender was not considered as a factor within the experimental study.

All groups were asked to carry out a navigation task in a VE. The test VE used was an

L-shaped ‘virtual corridor’ developed in VRML. The scene was kept as simple as possible

with rooms differentiated by colour. Participants were positioned to start at the entrance to

the corridor and then instructed to move into a set of six rooms consecutively within the

environment in search of various objects and then finally back to the starting position. The

navigation task incorporated precise, intricate movements such as entering or leaving a

room or turning around and moving around and behind objects, with larger movements

such as moving down the corridor. Travel inside the environment was based on an

egocentric, first-person perspective ‘walk’ mode where the part of the environment which

would be in front of the user’s own eyes was displayed and in which users controlled

movement using the mouse. Collision detection was used to prevent users moving through

objects or surfaces, and movement was confined to ‘walk’ mode.

Fig. 3. Creating a user-defined location.


Participants were briefed at the beginning of the experiment on the functionality of

whatever (if any) tools were presented. Each participant was allowed 15 min to practise

navigating. Each individual was observed while carrying out the task and was encouraged

to use a ‘think-aloud’ technique to record subjective comments. On completion,

participants were asked to complete a usability questionnaire which consisted of a set

of four statements designed to measure, using a scale of 1–5 (strongly disagree to strongly

agree), how easy it was to navigate, whether or not participants were able to complete the

tasks, how comfortable they felt using the application and how satisfied they were with the

navigational aids presented. The questionnaire also gave participants the opportunity to

comment on the most positive and negative aspects of their experience and to suggest how

it might be improved.

3.2. Experimental hypotheses and procedure

The research literature, along with our previous experimental results and observations

led to the following three hypotheses:

1. The older participants would perform equally as well as the younger participants

when provided with a range of navigational aids (i e. in the ‘all controls’ condition).

Table 1

The groups

Group Age group N

Control group 18–45 27

46 þ 7

Total 34

Map group 18–45 27

46 þ 7

Total 34

Speed group 18–45 27

46 þ 7

Total 34

Mark group 18–45 27

46 þ 7

Total 34

Undo group 18–45 27

46 þ 7

Total 34

All controls 18–45 28

46 þ 6

Total 34

Total 18–45 163

46 þ 41

Total 204


Dalgarno and Scott’s (2000) study identified a slight, but not statistically significant,

deterioration in navigation performance from the age of 40. With the provision of a

range of navigational aids, we predict that performance differences may not be evident.

2. The groups provided with visible navigational aids, either individually or all together,

would perform better and would be more satisfied with the interface than the control

group. The motivation for this hypothesis was derived from the lack of an interface

which provided a clearly usable range of visual tools, and the fact that participants

using the interface which displayed no navigational tools in earlier experiments gave

significantly lower usability ratings for the interface and even had to abandon the tasks

in some cases.

3. The group presented with all the available navigational tools would perform better than

the groups provided with only one navigational tool. This hypothesis is based on the

assumption that different users find different navigational aids most useful—while

some may become disoriented easily and find the map most useful, others may prefer to

move more slowly to perform intricate movements.

A two-way between-groups analysis of variance (ANOVA) was conducted. The two

independent variables were the interface presented and the age group, and the dependent

variable was the time taken to complete a navigation task.

4. Results

Table 2 shows the means and standard deviations of the time taken to complete the

navigation task for each age group across all conditions.

From this descriptive data, it can be seen that the participants in both age groups

obtained slower performance times when presented with the ‘control’ interface than all

other conditions and obtained the best performance times when presented with all the

controls. It is also noticeable that the older participants obtained worse performance times

than the younger participants in every condition. The overall performance times obtained

for the interfaces presenting individual navigation tools indicate that the ‘mark’ interface

produced the best performance times, followed closely by the ‘undo’ interface.

Examination of the results for each age group when presented with individual navigation

aids show that the 46 þ age group achieved the best result using the ‘undo’ tool while the

18–45 age group performed best using the ‘mark’ tool. Poorer performance times were

obtained for both the ‘speed’ and ‘map’ interfaces.

An ANOVA is the statistical procedure used to evaluate the results of an experiment

with multiple groups. ANOVA is used to uncover the main and interaction effects of

categorical independent variables (called ‘factors’) on a dependent variable. A ‘main

effect’ is the direct effect of an independent variable on the dependent variable. An

‘interaction effect’ is the joint effect of two or more independent variables on the

dependent variable. The key statistic in ANOVA is the F-test of difference of group

means, testing whether the observed differences in the means of the groups (great or small)

formed by values of the independent variable (or combinations of values for multiple

independent variables) are the result of chance or not. If the group means do not differ


significantly then it is inferred that the independent variable(s) did not have an effect on the

dependent variable. If the F-test shows that overall the independent variable(s) is (are)

related to the dependent variable, then multiple comparison tests of significance are used

to explore just which value groups of the independent(s) have the most to do with the

relationship.

The results of the two-way ANOVA conducted show that there was a significant main

effect of the interface presented on the time taken to complete the navigation tasks

(Fð5; 192Þ ¼ 15:52; P , 0:001). A significant main effect was also found for age group on

the dependent variable, time (Fð1; 192Þ ¼ 21:24; P , 0:001). The interface group and age

group interaction, however, was not found to be statistically significant

(Fð5; 192Þ ¼ 1:483; P ¼ 0:197), indicating that the effect of the interface presented was

not different for the two age groups. Both age groups performed similarly in all variations

of interface group.

An ANOVA tests for an overall experimental effect but does not provide specific

information about which groups were affected. To obtain this additional information, it is

necessary to perform some comparisons using contrasts. Two standard contrasts were

conducted: the first comparing all groups with the control group (‘no controls’); and the

second comparing all groups with the group presenting all the visual tools (‘all controls’).

Table 2

Age group descriptive statistics

Group Age group Mean time (min) Std. deviation

Control group 18–45 8.21 2.77

46 þ 13.06 2.44

Total 10.49 3.56

Map group 18–45 7.85 2.56

46 þ 9.71 3.35

Total 8.18 2.75

Speed group 18–45 6.45 2.70

46 þ 8.68 4.07

Total 6.77 2.97

Mark group 18–45 5.02 1.44

46 þ 7.19 2.44

Total 5.28 1.69

Undo group 18–45 5.62 2.09

46 þ 7.05 2.88

Total 5.91 2.30

All controls 18–45 4.56 1.60

46 þ 5.30 2.05

Total 4.63 1.62

Total 18–45 6.12 2.54

46 þ 9.87 3.89

Total 6.88 3.22


The results from the first simple contrast show that there were significant statistical

differences ðP , 0:05Þ in the time taken to complete the navigation tasks between each of

the groups displaying tools (map, speed, mark, undo and all controls) and the control group

with no navigation aids. In the case of the second simple contrast, where every group was

compared with the final group (all controls), a significant statistical difference ðP , 0:05Þ

was found with the ‘no controls’, ‘map’ and ‘speed’ groups, but no significant difference

was found between the ‘all controls’ group and the ‘mark’ (P ¼ 0:165) and ‘undo’ groups

(P ¼ 0:83). This suggests that these particular visual navigation aids were found to be

particularly useful, producing performance times relatively close to those achieved by the

‘all controls’ group.

Tukey’s HSD, the Bonferroni and Games-Howell post hoc procedures were carried out

to compare each group of subjects with each other. Tukey’s HSD and the Bonferroni post

hoc tests both control the type 1 error rate well (the probability of falsely rejecting the null

hypothesis), while the Games-Howell post hoc procedure deals well with population

variances (Field, 2000). Results from these tests confirm that, for each group, there was a

significant statistical difference between the ‘control’ group and all the others, as well as

between the ‘all controls’ group and the ‘control’, ‘map’ and ‘speed’ groups (P , 0:05).

No significant differences were found between the ‘speed’ group and the ‘map’, ‘mark’

and ‘undo’ groups, respectively, or between the ‘mark’ group and the ‘speed’, ‘undo’ and

‘all controls’ groups, respectively. Significant differences were found, however, when

comparing both the ‘mark’ group and the ‘undo’ group with the ‘map’ group. These results

indicate that the ‘mark’ and ‘undo’ tools were the most useful in helping decrease

navigation time.

4.1. Usability results

Figs. 4–7 display the ratings for each of the four statements presented on the post-

experimental usability questionnaire. Subjective ratings from 1 to 5, based on Nielsen’s

attributes of usability (Nielsen, 1993), were used to represent ‘strongly disagree’ through

to ‘strongly agree’, respectively:

Statement 1. Overall, I am satisfied with how easy it is to navigate using this interface.

Statement 2. I was able to complete the tasks successfully.

Statement 3. The interface has all the functions and capabilities I would expect it

to have.

Statement 4. Overall, I am satisfied with the tools presented on the screen.

The usability scores for Statements 1, 3 and 4 (Figs. 4, 6 and 7) show a similar trend to

the performance time results in that, for both age groups, the ‘control group’ was rated

lower than the interfaces displaying navigational aids. Fig. 5 (Statement 2) shows that

participants were generally able to complete the navigation task using all six interface

conditions—there was only one participant from the 46 þ age group was unable to

complete the navigation task when using the ‘control’ interface.

It is noticeable from Figs. 4–7 that younger participants scored the ‘control

group’ higher than their older counterparts in all four cases, suggesting that they


were less daunted by carrying out the navigation task without navigational support

presented on the interface. Younger participants rated the ‘mark’ tool very highly in

terms of ease of navigation (Fig. 4) and in relation to overall satisfaction with the

interface (Fig. 7).

Considering observations made during the experiments themselves, the results from

the questionnaire were sometimes surprising since there was often no correlation

between what was observed and the ratings given. From observation, for example, it

Fig. 4. Ease of navigation ratings.

Fig. 5. Usability ratings—ability to complete tasks.


was obvious that many younger participants in the ‘control group’ experienced a high

degree of frustration with the application, yet they often did not reflect this in the

ratings given. These anomalies may be explained by factors such as the novelty of the

3D navigation, not understanding or having adequate knowledge about the statements

presented, or ‘politeness’ since they were being observed.

Fig. 6. Usability ratings—expected functionality.

Fig. 7. Usability ratings—satisfaction.


5. Discussion

Since significant differences were found between the two age groups used in this

experiment, hypothesis 1 has not been supported by these experimental findings: provision

of a combination of navigational aids does not eliminate the age differences. The slight

deterioration identified by Dalgarno and Scott (2000) in navigation performance from the

age of 40 may therefore perhaps be attributable to the age factor. It is noticeable, however,

how performance times improved for older participants when they were presented with a

variety of tools (in the ‘all controls’ interface condition). In this condition, the least

difference in performance times between the two age groups was recorded with younger

participants achieving an average time of 4 min, 56 s and older participants achieving an

average time of 5 min, 30 s (see Table 2). Further work is necessary to investigate if this

difference can be reduced or eliminated with further navigational support.

The second hypothesis is supported by the results of the first simple contrast. There

were statistically significant differences found between the performance times obtained for

the ‘control’ group and each of the other interface conditions. The usability results also

confirm this finding in that lower ratings were consistently awarded for the ‘control’ group

and it was the only condition where a participant was unable to complete the set task.

These findings support the authors’ earlier experimental conclusions (Sayers et al., 2000),

emphasizing the need for the visual display of navigational aids on a two-dimensional

interface. This conclusion can be applied to users of all ages.

Hypothesis 3 predicts improved performance when a variety of navigation aids are

provided rather than a single aid and is partly supported by the findings from this study.

The interface displaying all the tools (‘all controls’) did produce statistically significant

navigation times when compared with the interfaces displaying a map function and a speed

function, respectively. There was no significant difference found, however, between this

group and the ‘mark’ or ‘undo’ groups. This result indicates that these two tools (‘mark’

and ‘undo’) were found particularly useful for navigation and this is supported by

observation of the participants, the ‘think-aloud’ technique employed, and the usability

ratings scored. From observation and comments it was clear that the ‘mark’ tool was

frequently used as a means of error correction—participants in both age groups used it to

index useful viewpoints within the environment, to which they then teleported when

encountering difficulty with the navigation task. The high usability ratings received for the

‘mark’ and ‘undo’ tools, when combined with the fact that there was no significant

difference found between their performance times and that of the ‘all controls’ condition,

point to the importance of effective error correction in the navigation process.

The map tool was not found particularly useful in this experiment yet this finding needs

to be treated with caution due to the small size of the VE presented. From observation of

the participants, it was noticeable that the map was used infrequently and participants

often stated that they found that they were not lost within the environment and did not need

to use the tool. Earlier studies by Ruddle et al. (1999) show the usefulness of maps for

navigation in very-large-scale VEs, so we can only conclude that a map might not be a

particularly useful navigational aid in small VEs.


6. Conclusions and future work

This paper has presented the results of an experiment designed to investigate the effect

of various interface tools and age on navigation performance times and user satisfaction.

From the results presented, we can say that age has a significant effect on 3D navigation

using desktop systems, with younger users consistently outperforming their older

counterparts. As the user community for these types of applications broadens, age must be

considered as an element in the design process, and the decrease in time differences

between the two age groups when presented with a variety of tools suggests that further

research into what factors might reduce (or eliminate) this gap are necessary. A study by

Emery et al. (2003) suggests that multimodal interaction may be the way forward when

designing for the next generation of older people who will be more familiar with computer

technology as it continues to integrate every aspect of modern everyday life. Emery et al.

(2003) found that the performance of older adults (aged 65 þ ) with varying levels of

computing experience, was improved when using a Graphical User Interface with the use

of some form of multimodal feedback (visual, auditory, haptic) as opposed to input, and

that this was more noticeable the higher the level of computing experience.

We can also conclude that the inclusion of visibly presented navigation aids has a

significant beneficial effect on navigation performance times for all ages, resulting in

better levels of user satisfaction. In addition, the abilities to mark user-defined locations

within an environment, and to undo actions were found to produce the fastest performance

times and to be the most highly rated individual tools. Further work involving large-scale

VEs is needed to thoroughly test the effectiveness of individual tools such as the map and

speed control facilities presented in this study.

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