Eye and Head Movement Characteristics in Free Visual Search of Flight-Simulator Imagery
Abstract
Free visual search (FVS) as defined here is performed while target objects are not visible, and when their possible spatial locations are not well defined. This situation is typical of real-world tasks such as air-to-ground target acquisition and search and rescue missions, but it involves gaze (i.e., combined eye and head) movements that are different from those used to perform laboratory visual search, which typically involves either clearly visible stimuli or well-defined spatial locations. In order to quantify those differences, responses were measured as observers searched for targets of both low and high conspicuity using instantaneous fields-of-view (IFOVs) of either 10 deg, 20 deg, or 40 deg. Gaze-saccade direction, amplitude, and duration, as well as fixation duration were obtained for the resulting gaze responses. Gaze-saccade amplitude increased from about 4 deg to about 7 deg as IFOV was increased, suggesting that no more than about 7 deg; of the visual periphery was effectively used in the visual search. Gaze-saccade amplitude and gaze duration increased, and fixation duration decreased, with increases in target conspicuity. However, only gaze amplitude varied significantly with IFOV. A two-parameter (scale and exponent) power function was fitted to the main-sequence amplitude-duration data. Both parameters varied significantly with target conspicuity, but in opposite directions. Neither parameter varied significantly with IFOV. Quantitative differences were found between the main sequence data associated with the present FVS and those previously reported for either simple step displacements of a target or for search among known target locations. As targets were not visible during the present FVS, the data may be taken to represent the degree to which higher-level processes modify more typical gaze-saccades made to targets present in the retinal image.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2010
- Accession Number
- ADA524435
Entities
People
- George A. Geri