The Influence Of Stimulus Saliency On The Representation Of Statistical Properties

Extracting the statistical properties of sets of objects which are not given focused attention in a scene is a function of our visual system, which is crucial for the human beings to adapt to the environment. Most previous studies of statistical processing of visual display have been focused on computing the mean sizes of groups of elements. Those studies suggested that judging the mean size of a group can occur efficiently and accurately even without focusing attention on each object. However, the elements of groups may not only vary in size but also in other quantitative attributes. In the current research, we observed the participants'estimations of the mean size of a group of circles, and explored the impact of stimulus saliency on the statistical processing by manipulating the luminance contract of the elements of the group of circles.We conducted 4 experiments in this research. In experiment 1, participants were asked to extract a statistical summary of the average size of a group of circles, of which stimulus saliency was varied by operating the luminance contract of the elements. In experiment 2, we adopted a partial report task to examine the validity of the saliency operation in Experiment 1. In experiment 3, we adopted two different distributions of sizes of circles, to examine whether stimulus saliency would impact the mean size extracting. In experiment 4, the mode of size estimation was required in order to explore the stimulus saliency effect when it was a task-relevant variant.The main findings of this study are as follows:(1) The representation of mean size of a group of objects is not impacted by the stimulus saliency. (2) Visual system can automatically compute the mean size of a group of objects with high efficiency and accuracy. (3)The representation by statistical properties is not appealing to focus-attention strategies.