1. A method for determining a pupillary response to a multimedia data element (MMDE) viewed through a user computing device, comprising: receiving a first image of a viewer's pupil captured prior to display of the MMDE over the user computing device; receiving a second image of a viewer's pupil captured after the display of the MMDE over the user computing device; determining, using the first image and the second image, if the viewer's pupil has been dilated; when identifying of a pupil dilation, querying a deep-content-classification (DCC) system to find a match between at least one concept structure and the at least second image of the user's pupil; upon identification of at least one matching concept, receiving a first set of metadata related to the at least one matching concept structure; determining the viewer's attention to the displayed MMDE respective of the first set of metadata; and associating the at least one MMDE with the determined user attention.