Detecting Sarcasm in Multimodal Social Platforms

Sarcasm is a peculiar form of sentiment expression, where the surface sentiment differs from the implied sentiment. The detection of sarcasm in social media platforms has been applied in the past mainly to textual utterances where lexical indicators (such as interjections and intensifiers), linguistic markers, and contextual information (such as user profiles, or past conversations) were used to detect the sarcastic tone. However, modern social media platforms allow to create multimodal messages where audiovisual content is integrated with the text, making the analysis of a mode in isolation partial. In our work, we first study the relationship between the textual and visual aspects in multimodal posts from three major social media platforms, i.e., Instagram, Tumblr and Twitter, and we run a crowdsourcing task to quantify the extent to which images are perceived as necessary by human annotators. Moreover, we propose two different computational frameworks to detect sarcasm that integrate the textual and visual modalities. The first approach exploits visual semantics trained on an external dataset, and concatenates the semantics features with state-of-the-art textual features. The second method adapts a visual neural network initialized with parameters trained on ImageNet to multimodal sarcastic posts. Results show the positive effect of combining modalities for the detection of sarcasm across platforms and methods.Comment: 10 pages, 3 figures, final version published in the Proceedings of ACM Multimedia 201

Preliminary study of dune deposits of the northern Lanzarote Islets. Palaeoenviromental implications

The dune deposits in the northern Lanzarote islets (Islotes) show the climatic changes (by sea level oscillations) en the last 40.000 years BP. Stratigraphic and faunistic analysis, as well as radiometric data, suggest that there are at last five sedimentary stages, ocurred during sea level regressions. The last episode has been dated at the end of the isotopic stage 2 and could be related with the last negative sea level oscillation (Younger Dryas episode). The fossil terrestrial gastropoda species are the same as the present ones in Islotes, Lanzarote and Fuerteventura, with few examples of exclusive taxon