In this recent article in Higher Perspectives, a study is highlighted that suggests that people who talk to themselves can perform better at a certain manual task, in this case, looking for a given product in a supermarket. The study is based on an experiment of 20 participants. Sometimes participants were asked to find a grocery item but had to remain silent, and other times, they were able to speak to themselves as they searched for the product.
The original research is based on a very small sample, and I don't see anything in the research that justifies the claim made in the graphic above that accompanied the Higher Perspectives article. Its also not clear from the HP article how the objects were chosen, and what controls were in place to prevent any other factors from contaminating the results.