Before revision:  Unfortunately, datasets have only limited cross-modal associations: images are not paired with others , captions are only paired with others that describe the same image, there are no negative associations and there are missing positive cross-modal associations.
After revision:  Unfortunately, datasets have only limited cross-modal associations: images are not paired with others , captions are only paired with other captions of the same image, there are no negative associations and there are missing positive cross-modal associations.