The ravens also demonstrated self-control skills: They were willing to forgo a reward in lieu of a better reward they had been trained to know would come 15 minutes later. Researchers presented the birds with a range of objects that included distractor objects, the useful tool or token, and a food treat. The treat was “less valuable” ― it’s not specified what this means, but presumably it was smaller and/or a food that ravens like less ― than the treat that ravens could later obtain by using the tool or token. (In control versions where no tool or token was available, the birds picked the immediate treat 100 percent of the time.)