Factors underlying inter-observer agreement in gaze patterns: predictive modelling and analysis

In viewing an image or real-world scene, different observers may exhibit different viewing patterns. This is evidently due to a variety of different factors, involving both bottom-up and top-down processing. In the literature addressing prediction of visual saliency, agreement in gaze patterns across observers is often quantified according to a measure of inter-observer congruency (IOC). Intuitively, common viewership patterns may be expected to diagnose certain image qualities including the capacity for an image to draw attention, or perceptual qualities of an image relevant to applications in human computer interaction, visual design and other domains. Moreover, there is value in determining the extent to which different factors contribute to inter-observer variability, and corresponding dependence on the type of content being viewed. In this paper, we assess the extent to which different types of features contribute to variability in viewing patterns across observers. This is accomplished in considering correlation between image derived features and IOC values, and based on the capacity for more complex feature sets to predict IOC based on a regression model. Experimental results demonstrate the value of different feature types for predicting IOC. These results also establish the relative importance of top-down and bottom-up information in driving gaze and provide new insight into predictive analysis for gaze behavior associated with perceptual characteristics of images.