My daughter likes listening to stories, but sometimes, she prefers just to look at pictures in books. This made me think about which form of content is more valuable for people: verbal or visual. Obviously, neither form can completely substitute the other one, but each has unique features.
Written stories (books) are best at stimulating imagination. Reading a book implies a collaborating between the author and the reader: it is impossible to provide all details of the story in words, so the reader has to use his/her imagination or project prior experience to fill in the gaps. So the impression of the given book is necessarily different for everyone, who reads it.
I think what makes visual images (paintings, photos, etc.) unique is that they have direct access to the viewer’s emotions. Generally, text is not enough to generate sensory perception of the scene. That is why war documentaries are important for indicting compassion towards the people involved in the wars, for example.
So, illustrated stories, which is a common format of children’s books is a perfect format for engaging the audience. This is a strong argument for taking time to write extended captions for photos that we post on social media (Flickr, Instagram, etc.) Alternatively, a good photoblog can be a series of photos accompanied by stories, rather than a simple gallery of images (social networks like 500px or Instagram can fill that nice more effectively).