For the caption-caption objective, we follow<cite> Kádár et al. (2018)</cite> and generate a sentence pair data set by taking all pairs of sentences that belong to the same image and are written in different languages: 5 English and 5 German captions result in 25 English-German pairs. The sentences are encoded and we perform an update of the model parameters using the same loss. When training with both the image-caption and caption-caption (c2c) ranking tasks, we randomly select the task to perform with probability p=0.5.