Semantic Gap between People: An Experimental Investigation Based on Image Annotation

Image annotation still remains the method of preference in multimedia search despite the development of many content-based multimedia retrieval platforms. Manual annotation is an extremely labour-intensive and time consuming task while the annotation expresses the view of a particular annotator at a specific context and time. Although the semantic gap has attracted large amount of research interest, the age and gender gaps in manual annotation have not been examined in detail. The aim of this study was to explore the gender and age differences in (1) the way of annotating images and, (2) the inter-annotator agreement. Our questionnaire based survey was conducted using 40 Cypriot citizens divided into two age groups who were asked to annotate an image dataset using a vocabulary of 52 keywords. Our results indicate that there are age differences in the way people annotate images, while the gender differences are smaller than our assumptions. Furthermore, there is an adequate agreement among participants for both age and gender groups.