Geography Reference
In-Depth Information
Apparatus and Set-Up
The user study was conducted in the Eye Tracking Laboratory of the Department of
Geography, Ghent University. This laboratory is equipped with an SMI RED
system, which registers the users
eye movements at 120 Hz. This remote eye
tracker was not used in its standard set-up, attached below a 22 in. screen, because
the stimuli with much larger dimensions had to be depicted. In order allow
objective comparison between digital and paper maps, the digital maps had to be
displayed at exactly the same scale, size and position as the paper maps. Conse-
quently, the eye tracker was used in a stand-alone mode and placed in front of a
large television screen. The TV is a JVC LT-50HW45U with a diagonal of 50 in.
and a resolution of 1,920
'
1,080 pixels (or 44 ppi). During the experiment, the
moderator could follow the participants viewing behaviour on a separate laptop.
This set-up is displayed in Fig.
1c
.
The paper maps were attached to the screen with tape. A black rectangle was
depicted on the screen, which indicated the correct position for the paper map.
Furthermore, the black colour avoided that too much light would be transmitted
through the paper map. In the set-up in Fig.
1c
, a paper map is displayed.
Using this stand-alone mode, a number of parameters had to be specified in the
eye tracking software (SMI Experiment Center), such as the viewing distance,
dimensions of the screen, position of the eye tracker relative to the screen, etc.
Dependent on the height of the participant, the inclination angle of the eye tracker
had to be adapted. Consequently, this parameter is different for each participant.
These settings are displayed in Fig.
1d
.
Methodology
To set-up the user study and subsequently analyse the data, a combination of
different software packages was used. This consists of software related to the eye
tracker (SMI), existing open source software (such as OGAMA), specialised
software (such as SPSS) and tools we have written ourselves, for example, to be
able to convert the data between the different programmes.
The study is
s Experiment Builder: specifying the stimuli,
their order, the parameters for the calibration, the parameters for the stand-alone
set-up, the questionnaire, etc. These settings were then used in combination with
SMI
'
s iViewX software, which drives the eye tracker during the tests. The recorded
data can be loaded into BeGaze (SMI). This software contains tools to do (mainly
visual) analyses with the data and export the raw or processed (fixations and
saccades) data in ASCII format.
In this experiment, it was decided to use the open source software OGAMA
(Open Gaze and Mouse Analyzer). This is an open source software, that can
visualise and analyse mouse and eye movement data, developed at the Freie
'
programmed
'
in SMI
'
