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Biomedical subjects

M Indra

Publications and source records attributed to M Indra.

At least 19 recordsLinked to original sources
PubMed1996

Manual tracing efficiency contingent upon stimulus shape and performance practice.

Tracing movements (hand-following the stationary contours of three two-dimensional figures: square, triangle and circle by means of a computer mouse-operated lightspot) were analyzed during five consecutive days. All three figures consisting of four (square, circle) or three (triangle) segments had the same circumference. Three parameters were chosen to express the tracing efficiency: average error, average time and performance quotient (average error per time unit) either for individual segments or the whole figures. The performance quotient was the best for the square and the worst for the circle, yielding better values for horizontal (than for others) segment orientation for the square and triangle. On the contrary, vertical segment orientation was found to be the best for the circle. The performance quotient and average error yielded better values in triangle segments when the right hand was used (all subjects were right-handed). However, considering the whole figures all three parameters displayed better values for the right hand. No differences were found with respect to the direction of tracing movements (clockwise or counter-clockwise). During the first three days both average error and time decreased, the change in later performance is caused by shortening of the average time only.

Adult↗
PubMed1995

Changing difficulty level in a one-dimensional tracking task and corresponding heart rate changes.

Subjects were required to track a target consisting of two vertical bars moving with either a constant or a sinusoidally modulated speed across an oscilloscope screen with a joystick-controlled light-spot. Either target size (distance between bars-size guided tasks) or velocity of the target movement (velocity guided tasks), varied throughout different tasks determined by subject's performance. The target's initial movement period was either 2 or 3 seconds. The following parameters were studied: time on-target intervals, time off-target intervals, number of tracking errors, heart rate and tracking error incidence over the cardiac cycle. Time on-target intervals were longer for the velocity guided tasks than for the size guided ones. The same was true for time off-target intervals. Values for both types of intervals decreased gradually over the fixed sequence of tasks for velocity but not for size guided tasks. Heart rate was higher in the size guided task. Tracking error incidence did not depend on the phase of cardiac cycle.

Adult↗
PubMed1994

A computerized modification of Sternberg memory test with additional perceptual distraction.

We describe a package of programs in Turbo Pascal which enables us to present six different versions of the modified Sternberg memory test and to evaluate the subject's performance. The program starts presenting a brief series of randomly generated visual stimuli (digits/colors) which are to be memorized, followed by the target stimulus. The series could either include the target or not. Noise in the form of colors or digits could be added to the stimuli. The reaction times of 'yes' or 'no' responses are evaluated separately and presented in numerical and graphic forms.

Algorithms↗
PubMed1993

EEG changes related to one-dimensional hand-tracking.

Central and occipital EEGs were recorded during one-dimensional eye-hand tracking in humans. A negative slow potential shift followed the commitment of tracking errors at electrode O1 and their correction both at O1 and C3. Error commitments were also followed by a relative decrease in alpha and beta-band power at O1, whereas their corrections followed a decrease in beta-band power at O2 and C3.

Adult↗
PubMed1992

A Turbo Pascal program for testing eye-hand coordination by means of tracing.

A Turbo Pascal program for eye-hand coordination testing using standard PC XT/AT mouse is presented. The contour segments of three simple figures (square, circle and triangle) are chosen as tracing trajectories. Tracing performance expressed in root mean squared (RMS) and modulus mean error (MME) measures are calculated and used, together with tracing time for evaluation of eye hand coordination ability.

Art↗
PubMed1991

Cardiac frequency, phase and errors in one-dimensional sensorimotor tracking.

One dimensional manual tracking was investigated in relation to actual heart rate and phase of cardiac cycle. Higher heart rate was combined with increased tracking error incidence and decreased successful tracking time (light spot inside target). Error incidence was time-locked with respect to the phase of cardiac cycle.

Electrocardiography↗
PubMed1988

Tracking irregular acoustic patterns by finger tapping.

Acoustical sequences were divided by time intervals of various durations, and the performance of finger tappings following the stimuli were recorded. The results proved that it is difficult to synchronize finger tapping with irregular acoustical patterns. The subjects tended to transform the irregular stimulus patterns into more regular response patterns shifted toward interval proportions close to 1:1 or 2:1.

Adult↗
PubMed1987

Tracking errors related to cardiac cycle: a new approach.

One-dimensional manual tracking was investigated in relation to cardiac activity. The task of the subjects was, by means of a joy-stick, to maintain a spotlight between two vertical lines moving horizontally across an oscilloscope screen. Error incidence was time-locked with respect to the cardiac cycle. Error rate was higher for faster (2-s trial periods) than for slower (3-s trial periods) target movement. Using linear-ramp and sinusoidal movements, it was demonstrated that error incidence is associated with positive and negative cardiac acceleration.

Adult↗
PubMed1987

Following complex rhythmical acoustical patterns by tapping.

Rhythmic acoustical sequences consisting of patterns of various complexity (number of intervals in pattern) were generated and subjects were asked to synchronize with them by finger tapping. Deviations between onset of stimuli and onset of response were measured. It has been confirmed that tapping precedes the onset of stimuli by about 20-30 ms. The duration of this anticipatory period increased with an increase in stimulus complexity to the limit of three intervals in pattern. This finding points to a systematic error in timing of rhythmic motor reactions during acoustical following. Its degree depends to a certain limit on the nature of the stimuli. Subjects are subjectively aware of this error.

Acoustic Stimulation↗