FACIAL EXPRESSIONS AND BODY GESTURES AS

METAPHORS FOR B2C INTERFACES

An Empirical Study

Dimitrios Rigas and Nikolaos Gazepidis

Department of Computing, School of Informatics, University of Bradford, Bradford, UK

Keywords: E-Business systems, Multi-Modal stimuli, Usability, Facial Expressions, Body Language, User Interfaces.

Abstract: This paper describes an initial survey and an experiment that investigate the use of facial expressions and

body language in e-Business applications. Our aim in this research is to investigate the usability aspects of

B2C interfaces that utilise speech, non-speech, avatars with facial expressions and gestures in addition to the

typical visual graphical metaphors that are currently used. The initial survey was performed with 25 users

and the main experiment with 42 users. Results were encouraging and enabled us to understand some of the

research issues involved in the use of multimodal metaphors in e-Business. The results indicated that avatars

with facial expressions were most preferred by users for e-transactions and the full animated body was the

second most preferred option by the users. The text was the least preferred option. These findings enabled

us to understand several design issues of multimodal systems for e-Business applications. For example there

were issues of multimodal presentation and combination of the different modalities, e.g. speech, avatars,

facial expressions, graphics, and text.

1 INTRODUCTION

User interfaces for e-Commerce (EC) applications

typically use text and graphics with the occasional or

limited use of multimodal features. Interfaces for

Business-to-Consumer (B2C) e-Commerce

applications are used widely for online shopping.

Many of these interfaces often use text and graphics

to communicate information with the occasional use

of auditory stimuli such as speech or earcons. On

overall, the use of multimodal metaphors in these

type of interfaces is limited. Multimodal metaphors

may include the use of speech (synthesised or

recorded), earcons (short musical stimuli), auditory

icons (environmental stimuli) or even human-based

avatars with facial expressions and body gestures.

Many of these different types of modalities were

found to be particularly useful in other applications.

Examples include the use of earcons to communicate

program executions (Rigas, 1998) and to improve

the usability of interfaces (Brewster, 1998a).

It is therefore believed that the use of different

modalities in interfaces for B2C will provide

additional benefits to the usability aspects to those

interfaces. The paper describes the initial part of an

empirical study that investigated facial expressions

and body gestures in e-Business applications.

2 RELEVANT WORK

Electronic Commerce (e-Commerce) is a general

term that incorporates any process relating to

buying, selling, or exchanging information

electronically among buyers and sellers, goods or

service providers and other third-party companies

(Barnes – Vieyra, 2001, Turban, 2003). A broader

definition of e-Commerce is e-Business which refers

to all the strategic moves, managerial decisions and

techniques of a business collaborating with other

business partners in internet or in private networks.

Interfaces for e-Commerce applications are often

very important for the successful utilisation of e-

Commerce transactions. The benefits for electronic

commerce include (Wendler, 2001):

Global impact: A good e-commerce site can reach

and appeal to any use of the World Wide Web.

Borderless customer base: Customers can be of a

variety of cultural or ethnical background.

275

Rigas D. and Gazepidis N. (2006).

FACIAL EXPRESSIONS AND BODY GESTURES AS METAPHORS FOR B2C INTERFACES - An Empirical Study.

In Proceedings of the International Conference on e-Business, pages 275-282

DOI: 10.5220/0001425102750282

 SciTePress

Staff reduction and cost savings (Tassabehji, 2003):

All the expenses for dealing and signing documents

from staff are lessen. Transactions are all based

online and a well designed e-commerce solution,

customers can resolve instantly any problem that

appears.

Presence in established or emerging virtual markets

(Mahadevan, 2002): New opportunities present in

B2B and B2C virtual markets. Businesses in order to

stay competitive they do a step further from a

traditional market to an electronic commerce.

Paperless transactions: The traditional way of the

use of paper is gradually becoming obsolete.

2.1 Multimodality

As e-commerce websites continues to expand the

need for interaction and multimodal contents

becomes noticeable (Böszörményi, 2001, Jalali-

Sohi, 2001). The use of speech, earcons and auditory

icons enhance user activities such as browsing and

may well improve the capabilities of an application.

Some different multimodal metaphors are briefly

reviewed below.

Auditory icons are non-speech sounds that simulate

physical sounds representing an event or an action

that took place (Bjur, 1998). Users are familiar to

these sounds and they know what they represent

since they derive from the natural environment. In

Gaver’s research (Gaver, 1993) is stated that

“Auditory icons add valuable functionality to

computer interfaces, particularly when they are

parameterized to convey dimensional information”.

Gaver’s SonicFinder is a well known auditory

interface he developed for Apple Computers (Gaver,

1989). He used natural sounds to map specific

operations for files such as copying, or deleting. The

benefits of sound effects were major and added

flexibility for the users in receiving information for

the interface (Gaver, 1989).

Earcons are non-speech sounds that use abstract or

synthetic sounds derived from instruments or

synthesisers. Earcons (as well as other auditory

stimuli) can attract the attention of the user or

announce to users an action or a result of an action

(Brewster, 1996). They do not appear visually on the

screen and they can vary on their level of sound

intensity (Brewster, 1998b). Brewster states that

users are overloaded with visual information when

they interact with computers (Brewster, 1997). His

experiments showed that interfaces could be

improved in terms of usability by integrating non-

speech sounds to the user interface widgets such as

menus, buttons, windows or scrollbars (Brewster,

1998c). Brewster, Wright and Edwards evaluated

and verified the benefits of auditory experiments

(Brewster, 1993, Borden, 2002). They derived some

guidelines on how a graphical interface can be

improved by the use of sounds. Users can work

more effectively when earcons are used in a

graphical interface. An additional auditory modality

can be used in the absence of users’ attention.

Speech metaphor is often used in multimodal user

interfaces so as to provide users with feedback along

with the graphical environment about system’s

current state (Preece, 1994) and it is a very useful

tool especially for visually impaired users (Lines,

2002). We distinguish two types of speech; natural

and synthesised. Natural speech output is a digitally

recorded message of a male or female spoken word.

It is often useful for applications that require short

sentences to be spoken but a dynamic use of

recorded speech by incorporating short recorded

messages (as building blocks) is a complex process

given the need for grammatical structure, context,

tone changes and phonemes. Large storage capacity

is also required due to the vast vocabulary (Lines,

2002, Preece, 1994). Synthetic speech output is

produced using a speech synthesizer. It can be

generated mainly by two methods: Concatenation or

Synthesis by Rule (also referred to as formant

synthesis) (Lines, 2002, Preece, 1994). Using the

concatenation method, digital recordings conducted

by real human speech are stored and later on

controlled as single words or sentences in a

computer (Preece, 1994). An example based on

concatenation is when someone uses a phone card

and a recorded voice informs the user how many

minutes left in the card. The audio message is

digitally recordings of each digit separately,

controlled by the computer system generating the

spoken message. Synthesis by rule, involves the

combination of synthesised words generated by rules

of phoneme. It is useful for large vocabularies and as

a result the quality of speech produced is poorer

compared to the concatenation method (Lines,

2002). Janse (Janse, 2002) had studied the

perception of natural speech compared to a synthetic

speech and derived that although synthetic speech is

becoming more and more intelligent, natural speech

still more comprehensible for listeners. A numerous

of studies on synthesised speech have shown that

natural speech still more intelligible and

comprehensible than the synthetic. Voltrax, Echo,

DECTalk, Voder, are some good examples of speech

synthesizers developed in the past but with poor

quality (Reynolds, 2002, Lemmetty, 1999).

Computer-based systems offer a speech

technology, known as Text-to-Speech (TTS)

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276

synthesis technology (Dutoit, 1999). TTS systems

have the ability to read any arbitrary text, they

analyze it and after converting it, they output it as a

synthesised spoken message comprehensible by the

user (Schroeter, 2000, Wouters, 1999). TTS

technology is widely used in software applications,

and many corporations are taking into account the

benefits of involving this technology in EC websites

(Kouroupetroglou, 2000). TTS brings out new issues

for the development of EC systems (Xydas, 2001)

and provides the scope for new innovative

applications.

We especially focus on the facial expressions

and body gestures that give a more realistic

interaction in human computer interfaces. The face

is a mean of expressing emotions, feelings, and

linguistic information and due to the improvement of

computer hardware (high performance graphics and

speed) instances of cartoon-like and human-like

synthesized faces are under development and

researched in depth for use in computer applications

(Beskow, 1996a). Animated or realistic characters

are used in spoken dialogue interfaces, conveying

information for verbal and non-verbal

communication by several means of facial

modalities e.g. lip-synchronization, eyes gazing and

blinking, turn taking and further advanced modeling

capabilities such as the use of gestures and motion

(Beskow, 1996b).

On the other hand, the use of gestures such as the

movement of the body, of hands and head, play a

major role in everyday communication. These are

often used either to give emphasis to our speech, to

point at an object or to illustrate the size or shape of

it. Gestures are also known as ‘body language”

communication (Benyon, 2005). In e-Commerce,

anthropomorphic agents introduce the use of speech

and gestures scoping to interact with the user. They

illustrate a mean of natural communication between

the human and the machine. For instance, an

animated character reading a text would differ from

a character which uses gestures as well, since

gestures themselves are movements conveying

information. It makes the character more dynamic,

more personal and believable motivating and it

affects users’ decisions since it combines

synchronised speech and gesture modalities

(Heckman, 2000).

Avatars are visual representations of an

interactive character in a virtual space displayed in

real time virtual environments (VEs) (Dix, 2004,

Benyon, 2005, Bartneck, 2004). These VEs have

been used for many web-based applications, and

they have been evolved in Collaborative Virtual

Environments (CVEs) (Fabri, 1999), where users

from any physical location they can interact,

communicate and cooperate with each other

(Burford, 1999, Prasolova-Førland, 2002, Krenn,

2004). Fabri and Moore (Fabri, 2005) argue that

when CVEs incorporates with facial expressive

avatars, can be beneficial for people with special

needs (e.g. autism), regarding their achievements

and their performance (Prasolova-Førland, 2002).

More particularly, avatars can be programmed

adopting artificial intelligence from the developer.

These animated characters interact with the user and

basically represents the presence of a mean of facial

communication in an application or in a website.

Avatars can be categorised and characterised in

abstract, realistic or naturalistic (Qiu, 2005, Salem,

2000):

Abstract avatars are non-humanoid avatars. They

are mainly embodied by cartoon or animated

characters, they have predefined actions and their

role is interactive between a computer application

and the user. Examples of abstract avatars are the

animated characters in Microsoft office suites by

giving tips and suggestions to the user during his

work process (Qiu, 2005, Hoorn, 2003).

Realistic avatars are highly accurate representation

of users. They are used in computer graphics and

animation, multimodal applications, console games

or even teleconferencing environments so as to give

a new high level of realism (Maria-Cruz Villa-Uriol,

1994). They take a set of static images or real time

video images in order to be used for the avatar. The

costs however of the technology and the hardware

that should be used are high (Qiu, 2005).

Naturalistic avatars are a humanoid approach, but

with low-level details. They are used in CVEs and

they ‘mimic’ some basic humans’ actions like

smiling, walking, or waving hands. These virtual

environments are three-dimensional and users are

entering the world represented by the form of an

avatar and a unique ID which interacts with other

users-avatars (Dickey, 2003). The most popular 3D

virtual worlds are Active Worlds (Active Worlds)

and blaxxum (Blaxxum).

3 RESEARCH PROGRAMME

User interfaces for B2C applications typically use

visual metaphors with the occasional or limited use

of multimodal features. This experimental

programme aims to investigate usability aspects of

B2C interfaces that utilise speech, non-speech,

avatars with facial expressions and gestures in

addition to the typical visual graphical metaphors

that are currently used. More specifically, some of

the research questions include:

FACIAL EXPRESSIONS AND BODY GESTURES AS METAPHORS FOR B2C INTERFACES - An Empirical Study

277

Figure 1: The experimental platform used for the experiments. A front view, B side view, C texture preview, D face

sculpting, E multimodal approach.

1. Does the use of natural or synthesised

speech have an effect upon the usability of an

interface? If so, which of the two increases the

usability of the interface?

2. Does the use of auditory icons and earcons

have an effect upon the interface?

3. Does the use of avatars with human like

facial expressions and different types of voice tones

have an effect upon the usability of an interface?

4. Does the use of avatars with human-like

gestures have an effect upon an interface?

5. Does multimodal overall provide less or

more efficient options for a candidate buyer through

the WEB upon his final decision?

Taking into account the recent experimental work

(as described in section 2) on multimodal metaphors,

including facial expressions and gestures, the

following hypothesis can be made:

“A multimodal e-Commerce website using

avatars with facial expressions and body gestures

would be more usable and desirable for the users’

decisions in terms of accomplishing e-transactions

when compared with text and graphics based e-

Commerce application”.

The initial survey and experiment described in the

sections below is the starting point to investigate the

above hypothesis.

4 AN INITIAL SURVEY

First, an initial survey was performed with 25 users

(20 males and 5 females) were used (most of them

were students from the University of Bradford, from

different departments). Each user answered

questions related to some personal details, education

level, and internet experience prior to the

demonstration of two websites for which their views

were elicited. A textual-based and a multimodal

website were demonstrated to the users individually.

The text-based version incorporated graphics and the

multimodal version incorporated multimodal

features such as speech output, face and body

animation. The aim of this survey was to explore the

usability, believability and likeability aspects of a

website that utilises multimodal features, whether is

preferable and more interesting or not. After the

demonstration of both versions (i.e., multimodal and

textual) of the website, users were required to

answer a short questionnaire relating to those two

demonstrations.

Figure 1 shows the face model and its various

stages of development that were used as a basis for

the animated face and body. A front view and side

view required in digital pictures format so as to

create a texture preview that will be attached on the

animation model and initiate the face sculpting. The

interface design consisted of two versions, i.e. the

multimodal and the textual. The multimodal

application was using of speech and animation and

the textual application was using text and simple

graphics.

The data gathered was checked and ensured for

its integrity and totality prior to further analysis.

Among the users a 60% had an average age of 22-30

years old, another 36% was between 18 and 21 and

only a 4% was over 30 years old. 80% of users were

males and 20% were females. 64% of the users

werein an undergraduate degree level, 20% were in a

doctorate degree and the percentage is lower for

people with a master degree and college education

that is 12% and 4% respectively. On the question

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278

Figure 2: Results in percentages of textual vs. multimodal website, multimodal metaphors and multimodal users’

preferences for EC websites.

“How many hours do you spend on the WEB?” most

of users answered more than 5 hours a

corresponding number of 44%. The rest of the

percentages are equally distributed to the rest of the

choices. These results can be seen in Figure 2. Users

were also asked if they had ever purchased items

from the WEB and 72% answered positive whilst

28% negative. The statistical analysis of the survey

showed that 76% of them preferred the multimodal

version than the textual where almost all of them

were very excited with the use of the multimodal

features referred above. In the question if they

would have been happier with a substitute of a face-

to-face contact when shopping online, 44%

answered ‘yes’, 32% answered ‘no’ and the

remaining 24% of the users did not consider it

important.

The results of the initial survey encouraged the

development of an experiment in which facial

expressions and body gestures were examined

further in a B2C application.

5 EXPERIMENT

The experiment evaluated three different interface

metaphors for a B2C application. These metaphors

involved the use of speech, animation, facial

expressions and body gestures for the presentation of

three products using three different ways (textual,

face, and full body animation). The experiment

measured aspects of usability, interactivity and

likeliness of the animating application. The

experiment was conducted with 42 users (34 males

and 8 females).

The B2C application developed involved three

products. The brand names of the products were

removed in order to avoid brand name influencing

user choice. Each product had a textual description

which was either presented visually for the textual

version or spoken for the face and full body

animated versions. In the spoken version, parts of

the textual description were emphasised.

FACIAL EXPRESSIONS AND BODY GESTURES AS METAPHORS FOR B2C INTERFACES - An Empirical Study

279

Figure 3: Results in percentages of the way users selected the presentation according to product and regardless of it.

Table 1: Key parameters for product description.

Key parameters Notation

Speech emphasis italics

Speech pause !

Head turning right } }

Head turning left { {

Head movement [ ]

Eye blinking ( )

Hands clenching # #

Open right palm > >

Open left palm < <

OK gesture √

Hands on waist * *

Finger gestures right / /

Finger gestures left \ \

Table 1 shows the notation for the speech

emphasis, gestures and body postures of the avatars

at particular places in the example of the text given

below.

“*The [(first)] and smallest handheld with

integrated 3-way (wireless) }capabilities} for your

data and voice communication that can be used }

worldwide*. > Itfeatures}> *Microsoft (Windows)

for a familiar [(environment)] to the user*. >It

[{provides]> (wireless) connectivity giving

/>access{ to the Internet, email and [wireless]

[(phone calls)]>/ at [very high-speeds].

\<[(Bluetooth)] technology is also available for easy

(data) synchronisation, file [(sharing)], [printing]

and [lastly]! it connects to GPRS (networks)<\.”

5.1 Results

Almost 50% of the users described the textual

presentations of the products as poor. However, only

33% of the users described the textual presentation

as good and 12% described it as very good. During

the post experimental interviews, users commented

upon the interactivity, attraction, eye-catching,

interesting and impressive aspects of the multimodal

approach. Some users also commented that it was

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280

easier to interact with a multimodal application

compared to the one that is dominated with text and

graphics only. The presence of the avatar gave a

positive impression to users. Therefore the face-to-

face approach was perceived by users that went

someway to simulate a real face-to-face shopping

experience.

As far as the multimodal metaphors are

concerned, users stated that speech output was

considered very important. Speech output was

selected by 87% of the users. All 42 users regarded

graphics as essential and that played an important

role in the interaction of the e-Business transactions.

Animated face was preferred by 80% of the users,

and animated body was preferred by 67% of the

users.

6 DISCUSSION & CONCLUDING

REMARKS

Many users expressed an interest to the use of

avatars with facial expressions and body language.

They thought that it would be helpful if such a

technique could be used in B2C applications. Users

preferred products that were presented using avatars

with facial expressions and body gestures than the

products presented using text and graphics.

Therefore the approach of using avatars with facial

expressions and body gestures has provided

sufficient scope for further experiments.

The experimental results so far have

demonstrated that there is some evidence to support

that this simulated face-to-face communication

between an online shopper and human like avatar

with human expressions and body gestures might

help on the usability of the online system.

It is believed that the ability of the users to

remember the information communicated by avatars

using the facial expressions and body gestures, could

be better from when the information was

communicated textually. Additional experiments are

needed in order to establish further the above point.

The anticipated benefits of continuing this

research will be to produce a series of empirically

derived guidelines for the designing of B2C

interfaces that incorporate avatars with facial

expressions and full body gestures in a multimodal

interaction. The use of the various facial expressions

and gestures would depend upon the different

interface instances and it is expected that guidelines

will be produced to address at least some of the

issues discussed above.

This research work described a survey and an

experiment to mainly investigate the use of facial

expressions and gestures in avatars that

communicate information about products in a typical

B2C application. The results demonstrated that the

multimodal approach taken was valid and that

human-like avatars with facial expressions and body

gestures have the potential to benefit the interaction

process in applications for e-Business transactions.

The avatars with the facial expressions was the most

preferred modality by the users (followed by full

body gestures). The lessons learned during these

epxeriments enabled us to identify issues of

multimodal presentation and combination of the

different modalities. A number of experiments are

currently designed to investigate these identified

issues.

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ICE-B 2006 - INTERNATIONAL CONFERENCE ON E-BUSINESS

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