2003 IMTA Proceedings - International Military Testing Association

direction, and stick movement produced cursor movement in the opposite direction. The cursor
movement algorithm introduced a constant rate of drift to the upper right. The 3 minute test was
preceded by 3 minutes of practice.
Rudder. The rudder task required subjects to operate a set of rudder pedals with their feet
to keep a crosshair cursor centered along a horizontal axis of dots. This axis and cursor appeared
on the screen simultaneously with the stick cursor and dot axes beneath the latter. Depressing the
left pedal caused the cursor to move to the right, and depressing the right caused cursor motion to
the left. This test was also preceded by a 3 minute practice session.
Throttle. The throttle task added a second joystick, operated with the left hand, to the
controls used to operate the stick and rudder tasks. Goal of the throttle task was to keep a third
cursor centered along a vertical axis of dots, left of the stick cursor and dot axes. The throttle
joystick moved in two directions only, toward the examinee and toward the screen. Movement
of the throttle produced movement of a vertical cursor in the opposite direction. This task also
was preceded by a 3 minute practice session.
Figure 1 from Biggerstaff et al. (1998) displays the apparatus used for all three
psychomotor tasks. Each task was scored as the total number of pixels a respective cursor is offcenter
at random intervals throughout the test. The stick task was administered alone over 3
minutes and in conjunction with rudder twice for 3 minutes each trial. Throttle was administered
only in conjunction with stick and rudder once for 4 minutes. The stick and rudder tasks were
also administered in conjunction with the dichotic listening task over 4 minutes.
Dichotic listening task. This task required subjects to focus on one string of audio
information in the presence of competing audio stimuli. Over 12 trials in 4 minutes, subjects
were presented simultaneous but different strings of alphanumeric characters to each ear. A cue
indicated which ear participants were to attend to during a given trial. Subjects were instructed
to key in the numbers they heard in the designated ear using a numeric keypad, but ignore the
letters. The task was preceded by 4 practice sessions over 3 minutes.
Horizontal tracking. This task required subjects to keep a square cursor centered on a
horizontal axis using a joystick, depicted in Figure 2 from Biggerstaff et al. (1998). The cursor
algorithm made the cursor accelerate as its distance from center increased, forcing participants to
attempt to ‘balance’ the cursor over the center point through small corrective adjustments. The
direction of joystick input matched the direction of cursor movement for this task. The
horizontal tracking task was administered in 7 sessions over 15 minutes.
Digit cancellation task. This task required subjects to enter randomly generated numbers
ranging from 1-4 on a keypad using their left hands as the numbers appeared on the screen. It
was administered alone for 2 minutes and in conjunction with the horizontal tracking task for 8
minutes.
Manikin task. This test assessed ability to perform mental rotations and reversals. It
consisted of drawings of a human figure holding a square in one hand and a circle in the other.
The figure was oriented in four ways over 48 trials: facing forward or backward and upsidedown
or upright. The task was to determine whether the square was held in the right or left hand
in a given trial. This task was not timed, and was not administered in conjunction with any other
tasks.
Score components
Due to relatively small sample size, a priori unit-weighted combinations of task scores
from various subtests were used to generate 4 broad component scores: psychomotor ability,
multitasking calculation, multitasking psychomotor, and visuospatial ability. Specific details of
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45 th Annual Conference of the International Military Testing Association
Pensacola, Florida, 3-6 November 2003