2. Recommending systems
■ help video-on-demand services consumers to
identify attractive movies or video content
■ personalized and non-personalized
■ non-personalized - without consumer profiles
analysis
■ Personalized – based on consumer profiles
3. 2 State of the art
■ Four classes of RS:
a) Collaborative - aggregate ratings or recommendations of objects,
recognize commonalities between users on the basis of their
ratings, and generate new recommendations based on inter-user
comparisons
b) Content-based - categorize the user based on personal attributes
and make recommendations based on demographic classes
c) Demographic - the objects of interest are defined by their
associated features
d) Knowledge-based - suggest objects based on inferences about a
user’s needs and preferences [Burke, 2002]
4. 2.2 Electrodermal activity
■ Old idea, 19th century
■ Skin conductance varies because of skin sweating that
is controlled by a sympathetic nervous system
■ Sweat gland activity increases if the sympathetic
nervous system is highly aroused
■ Used by many authors for stress detecting
■ decreasing in galvanic skin response when the game
difficulty has increased
■ horror, action and science fiction movies significant elicit
electrodermal response unlike comedy and drama
5. 2.3. Heart rate
■ essential indicator of the consumer’s
emotional state
■ average time between peaks of measured
waves
■ low arousal is associated with no heart rate
acceleration or deceleration, but high
arousal is associated with heart rate
acceleration and deceleration and generally
high heart rate
■ galvanic skin response and heart rate data
can be used for stress detection with 99%
accuracy
6. 3. Research – sample and methodology 1/3
■ 21 students ( between 20 and 33 years old) have watched
movie trailers, and differences between the female and male
group in electrodermal activity and heart rate have been
analyzed
■ 4 trailers, 2 action movies (“No time to die” and “Underwater”)
+ 2 romance movies (“I still believe” and “Little women”)
■ the movies that were not available in the theatres have been
chosen intentionally
■ Video clip – 618 seconds
7. 3. Research – sample and methodology 2/3
■ Students had headphones and Empatica E4 wrist band for
neurophysiological data recording
■ after every trailer student rated the trailer in the questioner
with a score between 1 and 10
■ beside the digit 1 on the questioner there is the text “I do
not want to watch!” and beside the digit 10 is the text “I
want to watch!”
8. 3. Research – sample and methodology 3/3
■ Empatica E4 wrist band is equipped with sensors for skin
temperature, blood volume pulse, motion and fluctuation
changes in electrical properties of the skin
■ Empatica E4 wrist band have to be connected with a
smartphone with Bluetooth connection while data is
recording
9. 3. Research - data processing and results
■ from the Empatica cloud, we could download
six files with some kind of data for every
student
■ all files were in CSV format, but for this
research, only HR.csv and EDA.csv are used
■ HR.csv contains average heart rate
frequency in a minute, and it is based on ten
seconds intervals. Frequency of sampling is
one sample per second
■ EDA.csv contains skin conductance values
sampled four times per second
10. 3. Research - data processing and results
■ a weak negative correlation between trailers scores and
standard deviation of heart rate has been found in the
female group data (R=-0,30; p=0,050).
■ a weak positive correlation between trailers/movie scores
and standard deviation of heart rate has been found in the
male group data (R=0,32; p=0,047)
0
1
2
3
4
5
6
7
8
9
0 2 4 6 8 10 12
St.dev.
Score
FEMALE GROUP
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
St.dev.
Score
MALE GROUP
11. 3. Research - data processing and results
■ raw data from EDA.csv file could
not be statistically analysed
without previous preprocessing
■ Matlab based software/plugin
called Ledalab has been used
0
2
4
6
8
10
12
1
90
179
268
357
446
535
624
713
802
891
980
1069
1158
1247
1336
1425
1514
1603
1692
1781
1870
1959
2048
2137
2226
2315
2404
uS
seconds x 4
12. 3. Research - data processing and results
■ Ledalab has been used for
decomposition of skin conductance
into tonic and phasic component
■ Ledalab provides discrete
decomposition analysis, and it has
been used
■ list of detected skin conductance
response have been available
13. 3. Research - data processing and results
■ difference between female and male students has been
analyzed with t-test and it is statistically significant but only
in skin conductance response number between genders,
regardless of the trailer genre
FEMALE
MALE
0
5
10
15
20
25
30
0-10 11-20 21-30 31-40 41-50 51-60
Numberofstudents-trailerstreams
Number of SCR per student-trailer stream
Female/male difference
FEMALE MALE
14. 5 Conclusion
■ Video-on-demand market is expected to grow from forty billion dollars in
2019 to almost ninety billion dollars by 2024
■ neurophysiological responses to movies and movie trailers can be recorded
in real-time and sent to Video-on-demand services, and it can be used to
improve service recommendation systems
■ for the begining, Video-on-demand service can reduce the cost of a
subscription if consumers use bracelets that record neurophysiological
responses, because lots of data are needed to build model
■ Our findings can be used to improve a recommendation system model,
because some corrections have to be made based on consumer gender
