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Camilli HFES-EC 2009
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Transcript of Camilli HFES-EC 2009
A short segment approach to cardiovascular
and ocular responses to task events and
mental workload changes
Marco Camilli, Arjan Stuiver, Willem Takens,
Francesco Di Nocera & Ben Mulder
Department of Psychology University of Rome "La Sapienza”, Italy
Department of Experimental Psychology, University of Groningen, The Netherlands
Background: Cardiovascular response [HR]
HRV (beat-to beat variations in interbeat interval)
decreases as mental effort increases. (e.g. Boucsein & Backs, 2000; De Rivecourt, et al., 2008)
Heart rate (HR) increases with an increase in mental effort.
(e.g. Roscoe ,1992; Wilson, 2001)
Background: Cardiovascular response [HRV]
HR spectrum - heart rate variability (HRV): low-frequency band (0.02–0.06 Hz) mid-frequency band (0.07–0.14 Hz) high-frequency band (0.15–0.40 Hz)
Mid-frequency band is most consistently related to
mental effort. (Mulder, 1985)
Background: Ocular response
Spatial distribution of eye fixations (by Nearest Neighbor Index: NNI)
Visual exploration pattern (fixations dispersion) is sensitive to mental workload changes.
(Di Nocera et al., 2006; Fidopiastis et al., 2009)
Fluctuating values by time series analysis. (Di Nocera et al., 2007)
Sensitivity to different types of task demand: visuo-spatial [éWLêNNI] vs. temporal [éWLéNNI].
(Camilli et al., 2008)
Camilli, M., Nacchia, R., Terenzi, M., & Di Nocera, F. (2008). ASTEF: A Simple Tool for Examining Fixations. Behavior Research Methods, 40(2), 373-382.
A Simple Tool for Examining Fixations
(ASTEF)
Objectives
Can HR(V) and NNI detect momentary
changes in mental effort, related to
specific task events in demanding and
less demanding conditions?
Ambulance dispatcher’s task [A1 call]
Ambulance dispatcher’s task [A1 activation]
Ambulance dispatcher’s task [A1 activation]
Ambulance dispatcher’s task [A1 ride]
Ambulance dispatcher’s task [A3 call]
Ambulance dispatcher’s task [A3 scheduling]
Ambulance dispatcher’s task [A3 scheduling]
Ambulance dispatcher’s task [A3 ride]
Method: task load conditions
Easy task load Hard task load A1 call + activation
A3 call
A3 activation
A1 call + activation
A3 call A3 activation
3 2 5 6 4 5
5 calls & 8 activations 10 calls & 11 activations
emergency ride
ordered transport ride
Ambulance dispatcher’s task
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Training Task & interface knowledge
Places on the map
Time distances between places
Trial condition
Condition Easy Hard
Duration 2 x 15 min 2 x 15 min
Measures
HR(V) and respiration frequency Eye movements NASA-TLX
Procedure & experimental design
N = 15
Remote testing lab
Operator’s workstation
Results: NASA - Task Load Index
F(1, 14)=7.19, p<0.05
Easy Hard
NA
SA
-TLX
[raw
sco
re]
HR(V) methodology
Time window (i.e. HR(V) mean values within 30 seconds)
“Spectral profiles” (indicators of spectral power as a function of time)
Har
te ra
te v
aria
bilit
y
Time line
Shifted forward each second
HR(V) methodology [cont’d] “Event analysis”
(effect of task events on mental effort)
Ride scheduling (40 sec)
No ride scheduling (40 sec)
No ride activation (40 sec)
Ride activation (40 sec)
Call Activation
emergency ride ordered transport ride
HR(V) methodology [cont’d] “Event analysis”
(effect of task events on mental effort)
Ride scheduling (40 sec)
No ride scheduling (40 sec)
No ride activation (40 sec)
Ride activation (40 sec)
Call Activation
emergency ride ordered transport ride
No scheduling work
F(1, 10)=31.47, p<0.001
During ride scheduling
Results: HRV around event [ordered transports] H
RV
[res
pira
tion
frequ
ency
ban
d]
HR(V) methodology [cont’d] “Event analysis”
(effect of task events on mental effort)
Ride scheduling (40 sec)
No ride scheduling (40 sec)
No ride activation (40 sec)
Ride activation (40 sec)
Call Activation
emergency ride ordered transport ride
Results: HRV around event [emergency rides]
p=0.06
F(1, 12)=10.13, p<0.01
No activation work
During ride activation
Easy Hard
HR
V [r
espi
ratio
n fre
quen
cy b
and]
Spatial distribution of eye fixations [NNI]
NNI methodology
Time window (i.e. NNI by using fixations recorded in 1 minute)
Shifted forward each second
“Time series” (indicators of scanning pattern as a function of time)
Nea
rest
Nei
ghbo
r Ind
ex
Time line
NNI methodology [cont’d] “Event analysis”
(effect of task events on mental workload)
Ride scheduling (40 sec)
No ride scheduling (40 sec)
No ride activation (40 sec)
Ride activation (40 sec)
Call Activation
emergency ride ordered transport ride
Hypothesis
During emergency rides activation
and during ordered rides scheduling
visual scanning pattern should be
more spread (i.e. more random)
respect to the segments where these
activities were not required.
Conclusions
HRV -in respiration frequency band-
showed to be sensitive to momentary
increases and decreases in invested effort
during different task events.
NNI should indicate a dispersed visual
exploration strategy in the short task
phases where addit ional cognit ive
resources may be requested.
Discussion
Most human operations are characterised by
unexpected situations.
Critical events could lead to instantaneous
peaks in invested effort.
“Event-based” methodologies might detect
these peaks and provide psychophysiological
indexes to use as trigger of adaptive supports.
Thank you for your attention…
HFES – Europe Chapter Annual Meeting October 14-16, 2009. Linköping: Sweden.