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acquisition modules, a DT2805 Multifunction Board, and a
Zenith Data Systems AT clone computer.
Heartbeat was monitored by a Colbourn Instruments EKG
Coupler recorded from standard lead II. Colbourn
Instruments Bipolar comparator was used to detect the R-peak
of the EKG. Sampling occurred at 200 Hz. The output of the
Schmitt trigger was sampled at the digital input port of a
DT2805 Multifunction Board installed in a Zenith Data
Systems AT clone computer.
Skin conductance was measured by attaching 4-mm Ag/AgCl
electrodes to the thenar and hypothenar eminences of the
palm ipsilateral to the lesion. To control for possible
hand effects NHD subjects were divided into left hemisphere
normal control (LH NC) and right hemisphere normal control
(RH NC) groups. The LH NC group had electrodes placed on
their left hand and the RH NCs had electrodes placed on
their right hand. One LHD subject had skin conductance
measured on his right hand because his left arm had been
amputated. Since recent evidence (Tranel & Damasio, 1994)
suggests that brain damage subjects do not display
differential skin conductance between their right and left
hands, it was decided to include this subject in the SCR
analyses. A 0.05 m NaCl electrolyte (Johnson & Johnson K Y
Jelly) was used. Colbourn Instruments Skin Conductance
module S71-22 was used to condition the SC signal. This is
a constant voltage system which passes 0.5v across the palm