Visual illusions in geology
Examples of visual illusions in the laboratory are well documented, but what about illusions that occur during field observation of geological structures? In this article I discuss a study involving geologists and non-geologists and define some of the problems that may arise during geological field and laboratory work.
A psychological analysis of observation in geology
ANALYTICAL methods of experimental psychology applied to observations of geological data reveal that what geologists perceive in, and remember of, rocks is not necessarily the same as what is actually there. For example, when observing folds, professionals give more attention to antiforms than synforms and tend to remember cleavage fans as they ought to be rather than as they are.
Pattern recognition and eye-movement parameters
Pattern perception was studied by recording eye movements while Ss visually scanned nine simultaneously presented patterns of asterisks for target patterns. Pattern parameters studied were: similarity of target patterns to non-target patterns (absolute difference in the number of elements), number of target elements, and frequency of targets. Systematic correlation between the first two pattern parameters and eyemovement parameters were found. Mean duration and mean number of fixations on targets and also on non-targets increased with increased similarity. Mean duration and mean number of fixations increased on targets with an increase in the number of target elements. Non-target patterns were perceived more auicfely than targets. Fixations of longer duration were required to perceive the original target than to identify the other target patterns subsequently. The eye-movement results provide the basis for developing inferences about higher order processing of visual stimuli.