Geography Reference
In-Depth Information
Table 2 Deviation (in x and y) and tracking ratio per test person
Part.
code
Deviation
X( )
Deviation
Y( )
Tracking
ratio (%)
Part.
code
Deviation
X( )
Deviation
Y( )
Tracking
ratio (%)
P01
0.5
0.9
93.8
P19
1.2
0.9
91.4
P02
1.1
1.9
91.0
P20
0.6
0.6
94.7
P04
0.2
1.3
91.4
P21
0.5
1.1
93.6
P05
0.4
0.6
95.1
P22
0.8
0.8
80.1
P06
0.6
2.4
66.7
P23
0.6
1.4
92.2
P07
1.2
1.1
96.4
P24
0.5
0.8
94.9
P08
0.8
1.3
96.4
P25
0.8
0.1
93.8
P09
0.7
0.5
96.3
P27
0.6
0.6
73.0
P10
0.8
0.6
88.8
P28
1.0
1.5
96.0
P11
0.4
0.5
95.1
P29
0.5
0.8
95.9
P13
0.8
0.7
96.7
P30
0.6
0.5
93.9
P14
0.7
0.9
92.3
P31
0.3
0.8
93.7
P15
0.9
0.8
96.2
P32
1.0
0.3
90.9
P16
0.7
1.6
95.6
P33
0.3
0.4
96.6
P17
0.3
0.6
93.6
P34
0.7
0.6
94.1
P18
0.6
0.2
95.5
P36
0.6
0.4
95.6
above 1 deviation are therefore deemed unacceptable. An overview of the partic-
ipants
deviations in X and Y is presented in Table 2 .
For several reasons (such as interference of other light sources, participants
'
'
movements, the range of the eye tracker, etc.) the eye tracker can lose the position
of the eye (pupil and/or registered reflection). No measurements are recorded in
these cases. Since the eye tracker was not used in its standard setting, it was of
utmost importance to check this ratio (% in time that the eye tracker could track the
position of the eye and thus record the participant
s POR). The result is listed in
Table 2 (last column) and shows that overall the tracking ratio is rather high. Only
three participants show a tracking ratio below 85 %, which is considered unaccept-
able for this study.
'
Visual Verification and Shift Correction
The parameters discussed previously do not give insights in the acceptability of the
recordings during the individual trials. Therefore, the eye movement data for every
trial (and participant) is inspected in OGAMA. The fixation module in OGAMA
allows visualising the fixations as dots on top of the corresponding stimuli. During
this visual inspection, it was noticed that the location of the fixations could be
shifted in the X or Y direction. The fixation module in OGAMA has a tool with
which the fixations can be translated over a certain distance in case of a shift. As a
consequence, the shifted measurements can be corrected and still be used in the
analyses. Other recordings could not be corrected.
Search WWH ::




Custom Search