A lecture on Psychophysiological (Biometric) methods given to Hanze University students in 2011. If you want to see more on this topic please check out these slide shows: http://www.slideshare.net/acagamic/next-generation-testing-biometric-analysis-of-player-experience and http://www.slideshare.net/keylimeinteractive/exploring-eye-tracking-for-games-user-research-a-case-study-of-lessons-learned

1. Psychophysiology & Games
Ben Lewis-Evans

2. >Introduction
 Kia Ora
 What and why?
 Biology
 Emotion &
Feelings
 The Measures
 Use in Games
 Limitations
 Demonstration

3. http://www.gamasutra.com/view/feature/6341/game_testing_and_research_the_.php

4. >What is Psychophysiology?
 Examining the signals the body provides in
an attempt to gain insight into what
psychological processes are occurring
 aka Whatcya Thinking?
- Emotion
- Mental Workload
- Stress/Tension

5. >Why use it?
 Questionnaires, focus
groups, interviews, talk
out loud, heuristic
analysis, psychometric
categories (“player types”)
- All Qualitative, All
Subjective
 Gameplay data &
Behavioural Observation
- Objective, but lacking in
the why

6. >Physiological Methods
 Pros:
- Objective, covert(ish), continuous,
quantifiable, reliable(ish), replicable(ish), with
good empirical power(sometimes) and can be
collected automatically
 Cons:
- Expensive, intrusive, difficult to analyse, and
time consuming (setup and analysis)
http://www.slideshare.net/acagamic/next-
generation-testing-biometric-analysis-of-player-
experience

7. >Biology
 Psychology = Mind?
 Embodied Cognition
- Psychology = Body
 Communication,
control, monitoring
and maintenance:
- The Nervous
System

8. >The Central Nervous System
 CNS for short
 Skull and top of the Spine
- Hidden away
- Hard to access
(for non-ninjas)
 Measures:
- fMRI
- PET scans
- EEG

9. >Peripheral nervous system (PNS)
 Controls internal organs (involuntary
muscles) and voluntary muscles
 Two parts
- Parasympathetic
- Rest, sleep - Maintaining body state
- Sympathetic
- Action, excitement - Emergency reactions
 Easier to access (no ninjas required)
 Measures:
- EMG, EDA, Cardiovascular

10. Berntson et al., 1994

12. >Emotion and Feelings
 Arousal and Valence
High Activation
Scared - x x – Excited
Unpleasant Pleasant
Bored - x x – Relaxed
Low Activation

17. >Emotions vs Feelings
 Somatic Marker Hypothesis
(Damasio, 1994)
- Emotions
- Body states (PNS and CNS)
- Can be unnoticed and
unconscious
- Feelings
- Subjective (conscious)
impressions of Emotions

18. Psychophysiological
Measures

19. >Electroencephalography (EEG)

20. >EEG
 Brain activity (CNS)
 Collects frequency information:
- Alpha 8-14 Hz (calm, mental
work)
- Beta 14-30 Hz (focused,
engaged mental work)
- Delta 1-4 Hz (trance, sleep,
fatigue)
- Theta 4-8 Hz (emotions,
sensations)
- Gamma 30-50 Hz
(Information processing –
not often measured)

21. >EEG Game Research
 Nacke 2010 – Wiimote vs Controller –
General increase in brain activity (EEG) when
using the Wiimote – In the delta band &
mainly for hardcore players (Delta is
relaxation/sleep/fatigue)

22. >EEG
 Advantages
- Access to the CNS
 Disadvantages
- Expensive
- Time consuming
- Invasive
- Artefacts
- Hard to interpret

23. >Electromyography (EMG)

24. >EMG
 Measures movement/activation in muscles
through the use of electrodes (PNS)
 Primarily interested in facial muscles for
Emotion (Valence) – other muscles for
tension?

25. >Facial EMG
 Three muscles of
interest:
- Corrugator supercilii
(brow) – negative
emotion
- Zygomaticus major
(cheeks) – positive
emotion
- Orbicularis oculi
(eyes)– expression of
enjoyment and
“genuine pleasure”

26. >EMG Game Research
 Nacke & Lindley
2008 – Flow and
Immersion in a FPS
- Effects of “boring”
vs “flowing”
gameplay in Half-
Life 2 on EMG.
- More positive
affect (Valence)
on the flow levels.

27. >Facial EMG
 Advantages
- More sensitive than
image processing
- Valence
 Disadvantages
- Intrusive
- Unnatural reactions
(monitoring effect)
- Expensive
- Artefacts
- e.g. No talking

28. >Electrodermal activity (EDA or GSR or SC or
SCR)

29. >EDA
 Changes in Skin
Conductance (PNS) As long as
1-5 seconds
- Sweat gland
activation
 Emotion (Arousal)
 Workload
 Tonic & Phasic
- Average vs Event

30. >EDA Game Research
 Nacke & Lindley 2008
– Flow and
Immersion in a FPS
- Effects of “boring”
vs “flowing”
gameplay in Half-
Life 2 on EDA.
- More arousal effect
on the flow levels.

31. >EDA Game Research
 Dying is fun?
 Ravaja et al (2008)
- EDA increased for
- Opponent Killed
- Player Killed
- EMG (Zygomatic
and Orbicularis)
- Increased for
longer when
player killed

32. >EDA
 Advantages
- Easier to collect
- Just 2 electrodes
- Non-intrusive
- Inexpensive
 Disadvantages
- Noisy signal
- Large individual differences
- Slow decay and response lag
- Specificity and artefacts

33. >Cardiovascular (HR, HRV, IBI, BP)

34. >Cardiovascular
 Measurement of heart
activity (PNS)
- Heart Rate (HR)
- Heart Rate Variability
(HRV)
- Inter Beat Interval (IBI)
- Blood Pressure (BP)
 Rhythms
 Useful as workload and
Emotion (Arousal) measures

35. >HR, IBI, HRV, BP
 HR
- Number of beats per unit of time
- with Effort/Arousal (initial)
 Inter Beat Interval
- Time between beats
- with Effort/Arousal (initial)
 HRV
- Variability in the IBI
- with Effort/Arousal (initial)
 BP
- Pressure of the blood
- with Effort/Arousal (initial)

36. >IBI/HR changes visible with the naked eye
REST TASK

37. >HR, IBI, HRV, BP
 Changes over time (~20 minutes) move
away from reactive “fight or flight” and
towards protective homeostasis
- Meaning that HR decreases and HRV
increases
 HR(IBI) vs HRV
- HR more sensitive to Emotion (Arousal)
- HRV more sensitive to Mental Workload
- 10 hz frequency band
- Use both

38. >HR

39. >HRV

40. http://gamasutra.com/blogs/BenLewisEva
ns/20110124/6676/My_Heart_on_Halo.php

41. >Cardiovascular Game Research
 Ravaja et al 2006 – Increase in self-reported
arousal, cardiac interbeat activity, and
zygomatic and orbicularis oculi EMG when
moving from playing vs computer to vs a co-
located stranger to vs a co-located friend

42. >Cardiovascular (HR, HRV, BP)
 Advantages
- Cheap and easy
measurement (HR)
- Captures emotion (arousal)
and Workload (HRV)
 Disadvantages
- Intrusive (BP, HRV)
- Specificity problems (affected by
many things)
- Complex analysis (HRV)

43. >Respiration

44. >Respiration
 Part of the Cardiovascular system (PNS)
 Sensitive to workload/effort
 Rhythms again
 Respiration impacts on other cardiovascular
measures and on EDA

45. >Respiration
 Advantages
- Relatively cheap and easy to
measure
 Disadvantages
- Not as sensitive as some
other measures
- Artefacts (No Talking)
Often overlooked, but in general it should always
be measured if you are measuring other
Cardiovascular variables or EDA

46. >Eye tracking

47. >Eye Tracking
 Measurement of Eye
Movement
- Can be done with EMG
- Electrooculogram (EOG)
- More commonly via an
infrared light camera
system
- Measures
- Where you are looking
and for how long

48. Heat Map

49. Fixations

50. >Eye Tracking
 Advantages
- Captures gaze and duration
- Relatively non-invasive
- Good for User Interface
 Disadvantages
- Gaze does not equal
attention
- Moving scenes with Depth
- Calibration!
- Glasses

51. Biometric Games

53. “[adding biometric readings for
players to see while playing was]
the most enjoyable thing we have
done" - Valve

54. Summary

55. >Limitations - Psychophysiology
 Fairclough (2009):
- Inference
- One-to-Many
- Many-to-One
- Specificity and generality
- Different tasks, people
and situations
- Validity
- Objective, yes, but to
what?

56. >Some comment from the industry
“We don’t use it...because the costs (both in equipment and time) has
always seemed to outweigh the benefits. Often we are better served
doing "standard" usability/playtests as we can do them quicker, faster,
and cheaper. ”
“Overall, I would say we find using biometrics to be incredibly useful,
but it depends on the genre of the game and what our clients are
interested in knowing. ”
“…we also don't use many of the biometrics due to the potentially
invasive nature of some of the measuring instruments. We strive to
provide a neutral, low stress environment for our tests”
“…we can imagine the benefits of using biometrics an such in some
cases, the imperatives of production usually mean that we wouldn't
have time to use them in an efficient manner”

57. >So?
 Not a silver bullet
 Do not use in isolation
- Combine with other
measures (not
talking)
 Try to look at Tonic
and Phasic reactions
 Use Baselines!
 Beware of artefacts!!
(not the BoP kind..)

58. >So?
 Great at arousal/workload and therefore
engagement.
- Not so good at valence (Pleasant vs
Unpleasant)
 Better at detecting things (emotions?) that
players may not be aware of themselves
- If players are not aware of it though, does
it actually affect their
enjoyment/behaviour?
- Will it influence their purchasing?

59. >Want more?
 Check out these presentations:
- Nacke, Next Generation Testing –
Biometric Analysis of Player Experience:
http://www.slideshare.net/acagamic/next-
generation-testing-biometric-analysis-of-
player-experience
- Rodriquez & Steiner, Exploring Eye
Tracking for Games User Research:
http://www.slideshare.net/keylimeinteracti
ve/exploring-eye-tracking-for-games-user-
research-a-case-study-of-lessons-learned

60. All images used in this
presentation belong to their
respective copyright
holders.
If an image belongs to you
and you wish it removed
please notify me at
b.lewis.evans@rug.nl