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Redundancy in interface design and its impact on intuitive use of a product in older users

Gudur Raghavendra Reddy*, Alethea Blackler*, Vesna Popovic*, and Doug Mahar **

* School of Design, Queensland University of Technology **School of Psychology and Counselling, Queensland University of Technology

Brisbane, Queensland, 4034, Australia raghavendra.gudur@student.qut.edu.au

{a.blackler;v.popovic;d.mahar}@qut.edu.au

Abstract: Many older adults have difficulty using modern consumer products due to their

complexity both in terms of functionality and interface design. It has been observed that older

people also have more problems learning new systems. It was hypothesised that designing

technological products that are more intuitive for older people to use can solve this problem. An

intuitive interface allows a user’s to employ prior knowledge, thus minimizing the learning needed

for effective interaction. This paper discusses an experiment investigating the effectiveness of

redundancy in interface design. The primary objective of this experiment was to find out if using

more than one modality for a product’s interface improves the speed and intuitiveness of

interactions for older adults. Preliminary analysis showed strong correlation between technology

familiarity and time on tasks, but redundancy in interface design improved speed and accuracy of

use only for participants with moderate to high technology familiarity.

Key words: Intuitive use, ageing, usability, cognition, interface design, design 1. Introduction Recent decades have seen a substantial increase in the use of technology in all aspects of our lives. The gradual

shift from hardware-based to microprocessor controlled software-based products has brought a higher level of

abstraction into interaction with products [1,2]. Members of older generations who grew up with older

technological paradigms have been left behind [3]. Furthermore, age-related decline in both cognitive skills and

sensory and physical abilities is also one of the contributing factors. Older adults are also less likely to use

complex devices intuitively and are slower when compared to younger people [4,5]. Although this realisation has

led to research on understanding the use of technology in the aged population, not much attention has been paid

to interaction design that would help older users in exploiting these new technologies [6].

This research proposes that designing technological products that are more intuitive for older people to use can

solve this problem. An intuitive interface requires minimal learning as it mostly relies on prior experience of the

users for effective interaction [1,7]. This paper discusses the results of an experiment investigating the

effectiveness of redundancy in designing interfaces that are intuitive to use for both older people and people with

low prior experience with related technology.

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2. Intuitive interaction At the time of this writing there are two groups of researchers, Blackler [7,8] and Hurtienne [1], working on

intuitive interaction and both have defined the basic nature of intuitive interaction. In terms of definition, both

the research teams agree that intuitive interaction is based on the past experiences of users and they use this

experiential knowledge unconsciously [9]. Intuitive use of an interface can be recognised by the following

characteristics:

(1) It is fast and effortless

(2) It is generally non-conscious and does not involve conscious reasoning or analysis and

(3) It is based on relevant past experiences.

2.1 Designing for older adults Many older adults have difficulties in using modern consumer products due to their complexity both in terms of

functionality and interface design. According to Docampo Rama [10] at least three factors contribute to this

difficulty:

(1) complexity of user interface,

(2) age-related changes in cognitive abilities, and

(3) generation-related differences in experience with technology.

However, a more recent study, on using technological products effectively, did not find any significant

generation-related differences in older people [11]. On the other hand, studies confirm that decline in cognitive

functioning affects the speed and accuracy of using complex technological products [5].

It is generally agreed that old age causes a decline in cognitive skills, which in turn affects learning of new

information. Not all skills are affected with aging, for example crystallised intelligence (like vocabulary) remains

constant or improves over age. Fluid intelligence (such as problem-solving, learning, and pattern recognition

abilities), on the other hand, declines markedly [12]. Moreover, research points out that this decline is not global

and varies from individual to individual. Recent studies on ageing and intuitive use of technological products

concluded that older people are an extremely diverse group and that familiarity and specific cognitive abilities

(central executive function) are more relevant to fast and effective use of products than chronological age [5,13].

The Central executive is an active component of the Working Memory system. It is a limited capacity system

used for tasks that involve decision making, directing attention to relevant information, suppressing irrelevant

information and allocating cognitive resources when performing more than one task simultaneously [14]. Central

executive function deteriorates with age and the effect of this decline becomes more pronounced as the

complexity of the cognitive tasks increases, such as when a task requires simultaneous storage and processing of

information [12].

2.2 Older adults and prior experience The way people handle current technology could be based on the kind of technology they were exposed to

during their formative years (10-25 years) [15]. People can be identified as belonging to certain “technological

generation” based on kind of consumer products technology they were exposed to in their formative years [2].

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Czaja [16] suggest that a group of people belonging to a certain technological generation will find it hard to use

devices from newer generations mostly because they lack prior experience with related technology.

Prior experience with technology is a strong predictor of performance on a variety of computer-based tasks [17],

such that the more experience a user has with related technology the faster they will learn to use newer ones [5].

Recent empirical research on prior experience and usability of products found that interactions that exploit user’s

prior-knowledge are significantly faster and are less prone to errors [5,13,18]. Furthermore, technology

familiarity (prior-knowledge) is also an important factor in intuitive use of an interface for older people [13]. On

the other hand, ageing causes, albeit at varying levels, decline in fluid intelligence, which in turn slows down the

acquisition of new knowledge. This could be one of the reasons why older adults find it difficult to use new

technological products intuitively [8].

3. Redundancy and intuitive use Some studies discovered that older users have difficulty assessing the functionality of interfaces that use graphics

extensively [19]. It is also observed that graphics based interfaces can increase extraneous cognitive load and can

have adverse impacts on learning their functionality [20,21]. It is suggested that using descriptive language to

define functionality of a button could help in using an interface intuitively [19]. Recent research also shows that

older people tend to perform better with words than symbols [8]. This research also suggests that redundancy in

interfaces might help older and users with low prior experience. Redundancy refers to repetition of content in

different format. The repetition has to be in alternative physical from, for example, voice and text or picture and

text [22]. Further more, redundancy of graphics and words is most beneficial to accommodate individual

differences in cognitive abilities [23].

There is a considerable amount of research in the field of educational technology that suggests the use of

multimodal representation to reduce the cognitive load for the learner. Cognitive Load Theory [24] is one such

outcome that is used extensively to inform the design of product’s user interfaces. This theory focuses on

efficient use of available cognitive processing ability for learning. Cognitive load can be described as the amount

of working memory resources used at any point during the learning process. Sweller [25] suggests that if

information is presented in two modalities, for example audio and visual, demand on working memory is

reduced. Research also indicated that more working memory is available when dual modalities are used [26].

Some interaction design research also suggests that redundant textual description that restates what is shown in a

diagram is very beneficial for novices or learners with no prior knowledge. However, redundancy is detrimental

to users with high prior knowledge [27]. Sweller [25] terms this as the redundancy effect, which states that if one

form of information representation is intelligible by itself, repeating it in another from will increase cognitive

processing load. For example, graphical interface with redundant textual (Figure 1) is helpful for novice users to

learn the function of this function, however, for expert users both forms of representation are intelligible, hence

redundancy effect.

Figure 1: Graphical representation of start function

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Gould and Schaefer [19] suggest that exploiting redundancy in interface design could help in making products

more intuitive for people with degraded cognitive ability and people with low prior experience. However, there

is no data available that supports their suggestion. On the other hand, some studies suggest that redundancy in

interfaces can have negative consequences for advanced or expert users [27]. In summary, although some

research indicates importance of redundancy in interface design there is no data available that informs us on the

impact of redundancy on intuitive use of a product. This experiment was designed to investigate if redundancy in

an interface has any impact on intuitive use, especially in older people.

4. Experiment design This experiment was designed to investigate whether the lack of necessary knowledge in older adults to interact

with the current generation technological devices [2] can be mitigated by employing redundancy in interface.

The research questions for this experiment were:

(1) Does redundancy help in using a product intuitively by novice (low/no prior experience) or users with age-

related cognitive degradation?

(2) Is redundancy in interface design detrimental for expert users?

(3) What are the differences, in terms of time on task, between age groups?

The design of the experiment was based on studies investigating intuitive use conducted previously [8]. This

experiment is a cross-sectional, between-groups matched-subject design. Participants for this experiment were

recruited from different sources to maintain a good sample of the general population. Individuals from various

organisations (like, sports clubs, educational institutes, recreational facilities and retirement resorts) were

approached to ask if they could volunteer to take part in this study. Overall 60 participants, 15 per age group,

participated in this study (Table 1).

4.2 Variables, methods and measurement tools The Dependent variables for this experiment were time to complete tasks and the number of intuitive correct

uses. This paper discusses the variable, time to complete task, only. The Independent variables and their levels

are listed in Table 1. Selection bias was controlled by matching participants in each level of both independent

variables. Furthermore, to minimise effects of extraneous variables participants were carefully matched for

gender, level of education, Technology Familiarity.

Table 1: Independent variables and their levels Independent variables Levels of Independent variables

Words only interface (uni mode) Symbols only interface (uni mode)

Interface design

Words plus symbols interface (redundant)

Young (17 to 39 years) Older young (40 to 59 years) Younger old (60 to 74 years)

Age

Older old (75+ years)

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In addition, following variable were measured to provide potentially useful ancillary data (Table 2).

Table 2: Ancillary measures

4.1 Apparatus and measures This experiment uses a commercially available body fat analyser as a test product. This device was selected after

carefully reviewing other over-the-counter health monitoring devices, including blood pressure, glucose and

cholesterol monitors. The decision to use the body fat analyser was primarily based on the assumption that this

product provides enough interest for both younger and older participants. Hawthorn [29] suggests that a test

product should be perceived as useful to sufficiently motivate the participants to engage them in the experiment.

For the actual experiment a virtual version of the product was used as it was not possible to modify the physical

device to test the “Interface” independent variable. The virtual product was used on a touch sensitive LCD

monitor. Two cameras were used to record the experiment (Figure 2a) for later analysis using Noldus Observer

software. One camera was positioned to record participant’s facial expressions and body language (Figure 2b);

and the second camera was positioned to record the tasks performed by the participant on the screen (Figure 2c).

Issues controlled Instrument used Impact on independent variables

Technology predisposition

Questionnaire People with high technology self-efficacy are less anxious when interacting with complex technological devices.

Lifestyle Questionnaire Pursuing challenging activities, learning new things. Research shows that a person who is mentally active by maintaining a challenging life style shows less age-related cognitive decline.

Cognitive measures

Cognitive measures software previously developed [28]

Working memory capacity and a measure of anxiety. Both processing component of working memory and anxiety impact intuitive use.

Vision Snellen reading chart Visual acuity

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Figure 2: Experiment setup with virtual device on touch screen monitor

(a) overall setup, (b) face camera view and (c) screen camera view

This research used triangulation of data collection methods. These were concurrent verbal protocol, observation

of interaction tasks, interviews and questionnaire rating scales. Observations were video and audio recorded

which are subsequently coded and analysed using the Noldus Observer, observational software. The Noldus

Observer assists in quantifying data based on combinations of independent variables, behaviors, and time criteria.

The data generated was exported into SPSS for statistical analysis.

4.3 Procedure This experiment was conducted in the QUT People and Systems Laboratory. The whole experiment was scripted

to ensure consistency between participants. Participants were first welcomed to the laboratory and were given an

information package that explained what the experiment was about, and what it meant to participate in it. Once

they understood all that was stated in the package and if they did not have any doubts about their participation in

the experiment, they were asked to sign the consent form. Then they were shown around the laboratory and the

experiment setup was explained. Once the participants were well settled and comfortable with the environment,

the experiment began. Participants were also informed that they could stop the experiment at any time and

request to delete all the records of their participation. The protocol of Experiment is listed with explanation in

Table 3.

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Table 3: Experiment protocol No. Activity Explanation 1 Technology familiarity

questionnaire Gather information on: Age, gender, education, life style and technology familiarity

2 Vision test A Snellen chart is used to measure visual acuity with, if any, prescription glasses or contact lenses.

3 Familiarisation session Virtual calculator is used to familiarise participants in using touch screen and concurrent verbal protocol

4 Anxiety test State anxiety test to measure the current level of anxiety of the participant

5 Task 1 Participants are asked to do Task 1 of the experiment 6 Task 2 Participants are asked to do Task 2 of the experiment. 7 Anxiety test Post experiment State anxiety test to measure the current level of

anxiety of the participant 8 Cognitive measures Interactive questionnaire to measure cognitive processing level of the

participant 9 Retrospective interview and

rating scales questionnaire. Semi-structured interview to gain an insight into reasons behind participants’ actions while performing tasks. Rating scales questionnaire to gather information on prior-experience of participants with interaction elements that are similar to the virtual test device

Task 1 involved switching on the device, inputting necessary details (age, gender, weight and height) and saving

the data followed by instructing the device to measure and display body fat mass and volume. Task 2 involved

switching the device on, recalling saved data, updating the data and instructing the device to measure and display

body fat mass and volume. Participants were informed that, if they were not comfortable to divulge their

personal information, they could provide false, but realistic, data. They were also informed that help would be

provided on request if they were unable to complete a task after repeated attempts.

5. Results and Discussion Preliminary results suggest that a negative relationship may exist between technology familiarity and time to

complete the task (Figure 3). Younger people (22 to 41 years) also tended to score higher on the technology

familiarity and were more likely to use interfaces faster than older people (59 and above years). Significant time

difference was observed between young and old in completing the task on redundant interface (Young = 4.33

minutes, Old = 7.33 minutes). Both these findings support results from earlier studies [5,8,13,30].

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Figure 3: Relationship between technology familiarity and time on task on redundant (Text and symbol) interface

However, contrary to the prediction, participants with low to moderate technology familiarity took more time

( = 6.67 minutes) to complete tasks on the redundant interface (text and symbol) than did those on text only

interface ( = 4 minutes). Moreover, younger participants with high technology familiarity were much faster

than their older counterparts on redundant (text and symbol) interface (young = 4.5 minutes, old = 8

minutes).

Processing-speed Theory, proposed by Salthouse [31], suggests that ageing causes slowing down of processing

speed. However, if older people were allowed more time on task, the performance differences between young

and old would be minimal. On the other hand, recent studies by Blacker et al. [13] and Lewis et al. [5] show that

older people also tend to make more errors. However, on text only interface of this study, in terms of time on

task and errors, there was very little difference between older and younger participants.

Moreover, it was observed that older people, when compared with younger participants, tended to take more

time to recover from mistakes and also appeared more anxious on difficult task, especially when they make

mistakes. This could be due to age related decline in central executive function which impacts ability to deal

with complex cognitive tasks [12]. Blacker et al. [13] have also reported relationship between central executive

function and rate of errors and time on task in older people.

6. Conclusion This study was designed to investigate if redundancy in product interface design facilitates intuitive use in older

people. The study involved participation of people of ages between 20 to 66 representing four age groups.

Preliminary results suggest a strong correlation between technology familiarity and time on task. Redundancy in

the interface did not improve speed or accuracy in participants with low technology familiarity. However, it had

a positive impact on people with moderate to high technology familiarity in using product interface much faster

and more accurately. The reason could be that all participants, as they were using this device for the first time,

are novice users. From this perspective, redundancy in interface did improve speed and accuracy in novice users

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with moderate to high technology familiarity when compared to interfaces that used only one mode of

representation (text only or symbol only). Further analysis of the data, taking into consideration age, education,

technology predisposition and lifestyle, is expected to give much more clarity in interpreting the data.

It was also observed that, when compared with younger people, the older people took more time to recover from

mistakes and also tended to get more anxious when task got difficult. Both of these issues will be further

investigated in next set of experiments.

7. Acknowledgements This research project is a subset of a larger investigation on intuitive interaction in older adults, funded by the

Australian Research Council (DP087764, RM2007000613).

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