Cardiac
Control During Dual-Task Performance of Visual or Auditory Monitoring
With Visual-Manual Tracking
R. W. Backs, J. Rohdy & J. Barnard |
Thirty
university students (15 females) performed tasks from the NASA Multi-attribute
Task Battery, which was used to manipulate the attentional processing
resource demands of the tasks. Separate groups performed visual or
auditory monitoring tasks singly and in combination with visual-manual
tracking while heart period, respiratory sinus arrhythmia (RSA),
and pre-ejection period (PEP) were recorded to determine the modes
of cardiac control during task performance. The tracking single-task
suppressed RSA and was interpreted as eliciting an uncoupled parasympathetic
inhibition mode of cardiac control because of its demand upon perceptual
and manual processing resources. The monitoring task both suppressed
RSA and shortened PEP and was interpreted as eliciting a reciprocally-coupled
sympathetic activation and parasympathetic inhibition mode of cardiac
control because of its demand for perceptual/central processing resources.
Dividing attention elicited uncoupled parasympathetic inhibition
that was greater for the visual monitoring and tracking dual-task
than for the auditory monitoring and tracking dual-task, which we
interpreted as indicating a greater sharing of perceptual/spatial
and manual processing resources for these tasks. Practice lengthened
PEP in the dual-tasks and was interpreted as eliciting uncoupled
sympathetic inhibition that was indicative of improved central processing
resource efficiency. The results are evaluated in terms of how knowledge
of cardiac control modes may be used to assess mental workload in
applications such as adaptive automation. Key words: divided attention, heart period, respiratory sinus arrhythmia, pre-ejection period |