2.3 Adaptation
As shown in (Karyotis, 2015) for the AT hypothesis
every person uses the basic elements in a
personalized way in order for them to select the
appropriate emotion label. For this to be accounted
in our model we implement a modified version of
the Adaptive Online Fuzzy Inference System
(AOFIS) (Doctor, 2005) as proposed in (Karyotis,
2015). With this method the user can provide new
emotion values if they aren’t satisfied with the
output of the system, also resulting in changes to the
fuzzy rule base. This will allow the system to adjust
its general rule base to a specific user, making it
more accurate and user-friendly. To achieve this,
when the user provides new values, a new training
sample is formed, and fed into the system. This new
data sample is used by the system to identify the
rules that fired and alter the consequent of the rule
with the highest activation value. This is
accomplished by calculating the optimal position of
the output fuzzy set's center of the highest activation
value rule, given the contribution of all the other
fired rules, and by mapping this value to the
corresponding output fuzzy set. Finally we propose
that the data samples collected offline from the
responses of a specific user at the online survey
described before to be presented one by one to the
system. This way the system will make all the
necessary changes to the fuzzy rule base, thus
creating a more personalised system before the user
starts using it in a real time setting.
2.4 Results
Since data collection is still ongoing, we used the
data collected for (Karyotis, 2015) in order to
demonstrate the stability of the system and
interpretability of the rules obtained from the fuzzy
method discussed above. The results acquired are
promising and can be improved and extended upon
completion of the data collection and processing
phase of the new user study described in the
previous section. In (Karyotis, 2015) the data were
collected following the method described in section
2.1. However this data do not account for the values
of arousal since the survey was aimed at modelling
the AT theory. We have inferred some arousal
values from the provided emotional values by using
the Affective Norms for English Words (ANEW)
(Bradley, 2010) database. The values we used for
valence correspond to the values of "current state" as
used in (Karyotis, 2015), since this variable was
used to describe how positive or negative valenced
the user was. To follow the aforementioned
methodology arousal, valence and prediction values
are considered as inputs for the first stage
classification systems. While for the second stage
classification systems, the inputs are: arousal,
valence and outcome values. For both stages the
outputs are values of the educational context specific
emotions: flow, excitement, calm, boredom, stress,
confusion, frustration and the neutral state. For a
chosen number of five fuzzy sets for both input and
output space we have computed the Normalized
Root Mean Square Error (NRMSE) using ten-fold
cross validation for stage 1 and stage 2 classifiers of
our proposed model (AV-AT) and of the model
proposed in (Karyotis, 2015) (AT) . For the adaptive
versions (Adaptive AT and Adaptive AV-AT) we
considered the values given from a specific
participant as changes they have provided during
their interaction with the system. The results are
shown in table 1.
To demonstrate the ability of the proposed fuzzy
approach to produce easily interpretable fuzzy rules,
we quote some examples of the rules extracted using
this method on the data from (Karyotis, 2015) for
excitement and flow.
Table 1: NRMSE of AT and AV-AT models using the proposed fuzzy method.
Emotions
NRMSE
Stage1 Stage2
AT AV-AT Adaptive AT Adaptive AV-AT AT AV-AT Adaptive AT Adaptive AV-AT
Flow 0,2559 0,2478 0,1823 0,2098 0.2359 0,2379 0,1724 0,1813
Excitement 0,2432 0,2292 0,1766 0,1770 0.2081 0,2094 0,1654 0,1712
Calm 0,2763 0,2502 0,2175 0,1810 0.2857 0,2573 0,1882 0,1820
Boredom 0,2386 0,2180 0,2057 0,1658 0.2199 0,2102 0,1413 0,1274
Stress 0,2689 0,2284 0,2134 0,2120 0.2473 0,2522 0,1652 0,1591
Confusion 0,2145 0,2063 0,1512 0,1376 0.2331 0,2311 0,1366 0,1375
Frustration 0,2174 0,2175 0,1428 0,1512 0.2001 0,1910 0,1455 0,1862
Neutral 0,2209 0,2215 0,1682 0,1442 0.2064 0,2057 0,1278 0,1186
Overall 0,2420 0,2273 0,1822 0,1723 0.2296 0,2243 0,1554 0,1579