Martin Riedl

Brandon Dang, Martin J. Riedl, Matthew Lease

Though detection systems have been developed to identify obscene content such as pornography and violence, artificial intelligence is simply not good enough to fully automate this task yet. Due to the need for manual verification, social media companies may hire internal reviewers, contract specialized workers from third parties, or outsource to online labor markets for the purpose of commercial content moderation. These content moderators are often fully exposed to extreme content and may suffer lasting psychological and emotional damage. In this work, we aim to alleviate this problem by investigating the following question: How can we reveal the minimum amount of information to a human reviewer such that an objectionable image can still be correctly identified? We design and conduct experiments in which blurred graphic and non-graphic images are filtered by human moderators on Amazon Mechanical Turk (AMT). We observe how obfuscation affects the moderation experience with respect to image classification accuracy, interface usability, and worker emotional well-being.

Sunny Mitra, Ritwik Mitra, Martin Riedl et al.

In this paper, we propose an unsupervised method to identify noun sense changes based on rigorous analysis of time-varying text data available in the form of millions of digitized books. We construct distributional thesauri based networks from data at different time points and cluster each of them separately to obtain word-centric sense clusters corresponding to the different time points. Subsequently, we compare these sense clusters of two different time points to find if (i) there is birth of a new sense or (ii) if an older sense has got split into more than one sense or (iii) if a newer sense has been formed from the joining of older senses or (iv) if a particular sense has died. We conduct a thorough evaluation of the proposed methodology both manually as well as through comparison with WordNet. Manual evaluation indicates that the algorithm could correctly identify 60.4% birth cases from a set of 48 randomly picked samples and 57% split/join cases from a set of 21 randomly picked samples. Remarkably, in 44% cases the birth of a novel sense is attested by WordNet, while in 46% cases and 43% cases split and join are respectively confirmed by WordNet. Our approach can be applied for lexicography, as well as for applications like word sense disambiguation or semantic search.