I__. - International Military Testing Association

Sub jects---Twen ty medical research volunteers from Fort Detrick,
MD, and Natick. MA, were subjects for study 1. Thirty two Ml-Al
a&Or personnei fr&n Ft. Knox, KY, participated in study 2. Al I
soldlers participated in these studies after they were given
physicals and were fully informed about the conditions and procedures
of the study. Investigators adhered to AR 70-25 and
USAMRDC Regulation 70-25 on Use of Volunteers in Research.
Assessment Instruments---The Number Compar i son Task involves
evaluating pairs of numbers to determine if the two numbers in
each problem are the same or different. In the first study,
automated and paper-and-pencil versions of the NC task ,wtre .
studied. The paper-and-pencil task (P-NC) was generated by
computer and printed on a laser copier. The automated Number
Compar i son (C-NC) task was administered on a GRiD Compass
portable computer. A subject’s response could not be changed
after it was entered on the keyboard of the automated task.
These assessment measures and experimental data are described
elsewhere (Shukitt et al., 1988).
METHOD
In the second study, two formats of the automated NC task
were studied. During testing, a display on a subject’s computer
showed either 1 or 33 problems to be evaluated. The later format
Was similar to the format used in study 1 on both versions of NC.
Procedures ---Both studies reported in this paper were repeatedmeasures
L designs and were incorporated into larger investigatlOnS
with other objectives. The first was to determine if an
amino acid, tyrosine, prevents some of the adverse behavioral
effects i nduced by environmental stressors. Specifically, 20
subjects were exposed to 4700 m of simulated high altitude and
17OC for 7 h; two other occasions they were exposed to 550 m and
22OC (baseline). The automated and paper-and-pencil versions of
the NC task were administered 300-320 minutes after ascent with
10 min separating their respective administrations.. Initially,
subjects practiced the NC task 15 times and learned to perform
quickly with