Ocular Search Pattern during Line Bisection Task in Normal Subjects

Lee, Byung Hwa; Park, Jung Min; Choi, Seong Hye; Yoon, Soo Jin; Jeong, Jee Hyang; Ha, Choong Kun; Na, Duk L

Abstract

BACKGROUND: The study of ocular search pattern in normal subjects and patients with hemispatial neglect may help understand spatial cognition. However, only a few studies are available that investigated ocular search pattern even in normal controls. The present study was to investigate ocular search pattern of normal subjects during line bisection task.
METHODS
Nine normal subjects (6 men and 3 women with mean age of 21.8+/-4.2 years) were requested to fix their eyes on the midpoint of the line that was presented on the monitor. Lines for bisection were varied according to the location (center, right-sided or left-sided) and length (short or long) and each subject performed 6 trials (one trial/condition). Horizontal eye movements were recorded using an infrared video-oculography and were analyzed in terms of the range and the direction of eye movements.
RESULTS
Average range of fixation during line bisection was 20.1% of entire length that corresponded middle portion of the line. There was no directional preference in searching the line during line bisection task.
CONCLUSIONS
We expected that normal subjects overtly look at both ends of the line before they bisect the line. On the contrary, they seem to use a strategy such that they directly go to the middle part of the line and then make fine adjustment while looking at both ends of line covertly. (J Korean Neurol Assoc 19(2):96~101, 2001)