AAWSAP DIRD, Cognitive Limits on Simultaneous Control of Multiple Unmanned Spacecraft, December 2010

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high frequency components which have different noise contributions (for example, core
temperature changes, blood pressure or speech, and respiration, respectively) .10
Blood pressure and its variability can also be measured. For continuous monitoring, a
finger cuff filled with water match the inner-arterial pressure and can be used to
monitor variability .11
CNS Measurements
Measurement of brain activity can be unobtrusively recorded using low-count
electroencephalography (EEG),e or the minimally obtrusive techniques of EEG, near­
infrared spectrometry (NIRS), trans-cranial Doppler sonography (TCDS), or the non­
invasive laboratory techniques of functional MRI (fMRI), magnetoencephalography
(MEG), or positron emission tomography (PET). The latter three techniques are for
brain research only and do not have any current naturalistic research studies (although
see Genik12 for a prognosis on generation-after-next technologies including NIRS, PET,
fMRI, and MEG).
EEG measurements are typically divided into spectra and the relative power in the
bands 0-4 Hz(!\), 4-8 Hz (0), 8-13 Hz (a), 13-30 Hz(~), and 30-100 Hz (y). NIRS
measures the BOLD effectt and is related to localized y activity. TCDS measures CO2 as
the byproduct of localized increased metabolism and is also an indirect measure of
neural activity which has been shown to be related to vigilance. 13 For EEG experiments
in mental workload, changes are typically reported in the 0 and a bands, though more
recently ~ and y bands have shown sensitivity .14
Event-related potentials (ERP) are peaks of activity measured at the skin indicative of
several tens of thousands of neurons firing coherently for a short time. For example, a
well-studied cognitive ERP is P300, a lO's-of-msec-wide bump in the EEG signal
occurring 200-400 msec after an event. Some success in utilizing a task-irrelevant
secondary audio stimulation and NlOO has been shown,15 but little further development
to this approach has been found in the last 15 years.
Ocular Measurements
Measurements involving eye fixations, dwell time (temporal length of a fixation), and
pupillary changes are well established metrics of workload in visual searching tasks. 16
Additional measures of ocular changes include blink rate, blink duration, blink latency,
and eye movement. These are recorded using one of various types of eye-tracking (ET)
or electrodes to measure an electrooculogram (EOG). ET data will include position of a
fixation and the time of each eye movement (or saccade), whereas an EOG only
identifies the time that the muscle controlling eye blinks or eye position activated.
• Low-count EEG is generally less than 10 electrodes, and usually 3 or 5.
r The Blood Oxygen Level Dependent (BOLD) effect is a local change in the oxygen saturation ratio near neural
activity due to metabolic and vascular action . This change is detectlble in the infrared spectra.
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