Word employees to Google
Recently, users on Twitter have asked John Mueller of Google if the use of stock images affect on SEO and search results. Mueller replied:
"not impact directly search the web"
Despite the answer a little vague and indirect (typical of Google SEO experts) can be drawn from the useful considerations.
We see more often that the best positioned websites use stock images. This disproves the idea a bit 'backward that non-original content adversely affect the rankings. But you always have to see what kind of content.
stock photos are not original content. However, Google would not dream of penalizing them, or more than half of existing sites would have big problems.
"For image search would be ideal not always have the same between the results (There is also the potential impact on users: could the whether they are only stock pictures affect conversions?) "
Use them the best means to do it with a strategy in mind. Sometimes a metaphorical use may not be the right choice. Example: the image of a professional climber in an article headline "The climb to success."
The images out of context are not the best in terms of involvement and consistency.
If the climb would agree to use something more concrete, like a student who graduates or someone who is hired by a major company. This will surely give the idea of success keeping in theme with the article.
Other test for judging how an image is relevant to the topic is studying snippets out. By analyzing what is put in the foreground and most clicked will be able to draw up generic guidelines for choosing the next cover images. Usually images closely related subject and be able to communicate an answer tend to produce excellent results.
short, use stock pictures has no direct effect on SEO. It mainly depends on the use made of it. Be more relevant and choose the right ones in relation to the subject treated may push users to click, but behind it all there must still respect for the traditional rules of indexing.