Size matters: saccades during scene perception.
We investigated the effect of image size on saccade amplitudes. First, in a meta-analysis, relevant results from previous scene perception studies are summarised, suggesting the possibility of a linear relationship between mean saccade amplitude and image size. Forty-eight observers viewed 96 colour scene images scaled to four different sizes, while their eye movements were recorded. Mean and median saccade amplitudes were found to be directly proportional to image size, while the mode of the distribution lay in the range of very short saccades. However, saccade amplitudes expressed as percentages of image size were not constant over the different image sizes; on smaller stimulus images, the relative saccades were found to be larger, and vice versa. In sum, and as far as mean and median saccade amplitudes are concerned, the size of stimulus images is the dominant factor. Other factors, such as image properties, viewing task, or measurement equipment, are only of subordinate importance. Thus, the role of stimulus size has to be reconsidered, in theoretical as well as methodological terms.
von Wartburg
Roman
R
Perception and Eye Movement Laboratory, Department of Neurology and Department of Clinical Research, University of Bern, Inselspital, CH 3010 Bern, Switzerland.
Wurtz
Pascal
P
Pflugshaupt
Tobias
T
Nyffeler
Thomas
T
Lüthi
Mathias
M
Müri
René M
RM
D000328:Adult; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D012438:Saccades / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D012858:Size Perception; D014796:Visual Perception / Q000502:physiology*