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
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
12. >Emotion and Feelings
Arousal and Valence
High Activation
Scared - x x – Excited
Unpleasant Pleasant
Bored - x x – Relaxed
Low Activation
13.
14.
15.
16.
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
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
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
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
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)
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
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)
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
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
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
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