Over time, as they experience the world, the toddlers refine their abilities and focus on what's really relevant, say, human faces rather than monkey or dog mugs.

If you find an image you like, but it's not quite what you are looking for, hover over the image and select Show similar images to refine your search to images that share a similar characteristic.

So it's better to start off with a simple story and refine it slowly over time.