Preemptive Action
Accelerating human reaction
using electrical muscle stimulation
without compromising agency

Core question for today’s talk:can we accelerate reaction time
without compromising agency?

1. related work
the sense of agency

sense of agency: feeling of control over actions and their consequences
this is fundamental to the way we interact in the world:
1. it is linked to self-awareness [Gallagher, '02]
2. its disruption is linked to neurological disorders [Frith, C, '92]
3. It is a core value in our community [Shneiderman’s rule#7]
Frith, C. (1992). The Cognitive Neuropsychology of Schizophrenia.
Gallagher, S. (2002). Experimenting with introspection. Trends Cogn. Sci
Shneiderman, B., and Plaisant, C. (2004). Designing the User Interface: Strategies for Effective Human-Computer Interaction

userinterfaces
humanactuation[Gu et al., CHI’16]

Intention

Voluntary
actionconsequences

SystemIntention

Actuationconsequences[Tamaki et al., CHI’11][Saraiji et al., SIGGRAPH eTech’ 18]humanactionIntention

Voluntary
actionconsequences

NO sense of agency

human
actuation

SystemIntention

ActuationconsequenceshumanactionIntention

Voluntaryaction

consequences

sense of agency?

human
actuation

SystemIntention

ActuationconsequenceshumanactionIntention

Voluntaryaction

consequences

NO sense of agency

human
actuation

SystemIntention

Faster Actuation consequences

2. our approach
delay the actuation timing

too early
not me!

too late?

ups…

experiment #1

experiment #1: design
visual stimulus

user taps
EMS0 msreactionreaction
time time
EMS offset time

300 msexperiment #1: design
visual stimulus

user taps
EMS0 msreaction time
EMS offset time
-300ms ~ 400ms

300 msexperiment #1: results
too early, no agency

experiment #1: results
Undistinguishable:EMS move ≈ own move
8 out of 12 said in several trials:“I did not realize I had EMS”

7543
2

Perceived agency score

6

this is an individual participant’sown (unassisted) reaction time

1-100

0100

200

Reaction time [ms]300400own reaction time
Preemptive Gain

EMS offset

reaction time(accelerated)0.50

Perceived agency score (normalized)

1400

300

200

100

Preemptive gain [ms]0-100-200

0.50

Perceived agency score (normalized)

1400

300

200

100

Preemptive gain [ms]0-100-200

Preemptive Action : generalized model

80 msRemaining questions
PreemptiveAction : generalized model

human responsible for speeding up ?
What happens, if we don’t have intention
80 ms

EMS tingling sensation causes lose of agency?

experiment #2: design
same apparatus + added control conditions
1. preemptive EMS (80 ms)
2. Relax EMS. (80 ms)
3. user moves + EMS tingles (80ms)
4. preemptive EMS (240 ms)
Participants were not aware of fourconditions

experiment #2: results
finding#1: human intention was not responsible for speed up

preemptive EMS
80 ms

Relax EMS
80ms
no intention

experiment #2: results
finding#2: … but agency score is much better with 80 ms preemption.

preemptive EMS
80 ms

Relax EMS
80ms
no intention

experiment #2: results
finding#3: EMS tingling drops agency slightly, but time and movement is more important

preemptive EMS(80 ms)user moves + EMS
tingles (80ms)

Fasterpreemptive EMS(240 ms)

3. implications

1. human/machine must havealigned intentionsPreemptiveAction

2. relationship between agency andpreemptive gain

Voluntary
Action80ms

EMS

4. applications

application #1: pen-drop

EMS preemptive gain:application #2: high-speed photography

application #2: high-speed photography

application #2: high-speed photography

application #3: hitting moving target

application #3: hitting moving target

5. conclusions

conclusions: summary
1. human/machine must havealigned intentions
PreemptiveAction

2. relationship between agency andpreemptive gain is not linear (or binary

VoluntaryAction

80msEMSconclusions: open questions
1. alternative methods for measuring agency (intentional binding)
2. complex situation (cognitive loaded , complex motion, incongruent intention)
3. how to weigh in other factors (e.g., context, attention, priming, etc.)

… thanks, questions?

p.s.: come to our demo at SIGGRAPH’ 19 eTechOutcome bias
'the sense of agency depends on a retrospective
comparison between expected or desired action
outcomes and actual outcomes’[Wegner and Wheatley, 1999][Blakemore et al., 2002]

Wegner, D. M., and Wheatley, T. (1999). Apparent mental causation. Sources of the experience of will. Am. Psychol.
Blakemore, S. J., Wolpert, D. M., and Frith, C. D. (2002). Abnormalities in the awareness of action. Trends Cogn. Sci

Why we did not use Intentional Bindings

BEYOND tapping test ------ cognitive loaded task

Stroop Test ‒ cognitive loaded taskREDBLUEREDBLUE

Reaction time > 500ms / sometime human makes mistake