Stimulus determinants of the phenomenon of change blindness
This article describes techniques and procedures that are used to research the changeblindness phenomenon. The role of stimulus parameters in completing a visual task (detecting changes) was investigated. The following parameters of visual stimuli varied in a chronometric experiment: the number of objects, their location in the stimulus space, and the shape of the objects (including a new object that attracts attention as well as various changes of single objects, such as appearance/disappearance, location shifts, changes of color and shape). The results of this study indicate that change blindness can have a different intensity (the time of detecting changes in flickering images) depending on the number of objects, their location in the stimulus space (structured or randomized), and the type of change (the most complicated one was a change of color):
- The number of objects has considerable influence on the intensity of change blindness and is the most powerful parameter.
- The shape of the objects within the image is not crucial for change-detection time.
- The spatial organization of the objects is important for the successful detection of changes. The changes are detected quicker in images with regular rather than random organization.
- A distraction (in this case, a word that was substituted for an object) doesn’t have any considerable influence on change detection.
- Change-detection time increases as the interstimulus interval increases from 200 to 400 ms.
- The detection of shifts and of appearance/disappearance is quicker than the detection of color change.
These results let us create stimulus patterns for change-blindness experiments that differ in complexity, and thus we could examine a wide range of hypotheses about the function of the psychological mechanisms of spatial attention that are used to explain this phenomenon.