Researchers have known for a long time that what’s going on psychologically can affect how people perceive the world. For example, underprivileged kids rate coins as bigger than they actually are, and people who are hungry rate food as being more vividly colored than it is.

But it’s been unclear where this “bias” occurs in the system: Is it in the earliest phase, when the brain is simply taking in the information, or is it in the final phases, when the “highest,” executive level processing occurs?

To answer this, a team had 42 normal-weight college students come in to the lab after three to four hours of not eating. Half of the students were told there was a delay in the experiment, and they should go get lunch and return in an hour. The other half was told the delay would only be about ten minutes, so they were still hungry when the experiment began.

These results suggest that the “bias” is occurring at the very earliest stages in perception – before the brain has even processed what it’s seeing.

During the experiment, the students watched a computer screen, on which cue words flashed: Cues were either food-related (like “cake”) or non-food-related (like “boat”). The words appeared for only 33 milliseconds, which is just at or below the level of perception, so people are not generally able to perceive the words that they’re seeing in this amount of time. The students were all asked to rate how bright the words were.

The participants who were hungry rated the food-related cues as brighter. They were also better at identifying the food-related cues than the neutral cues, even though they were technically below the level of perception. For the non-hungry students, it did not make a difference in the type of word they were seeing. These results suggest that the “bias” mentioned earlier is occurring at the very earliest stages in perception – before the brain has even processed what it’s seeing.

“This is something great to me, that humans can really perceive what they need or what they strive for, to know that our brain can really be at the disposal of our motives and needs,” said lead author Rémi Radel said in a news release. “There is something inside us that selects information in the world to make life easier.”

In other words, we see what we want to see, the authors explain. The results of the study also help explain why we may buy more (and perhaps make not-so-healthy choices) when we shop when we’re hungry and why dieting can be so difficult. That our internal states can affect what we see, even at a subliminal level can have important consequences for the choices we make is areas of life not related to food as well.

The study was carried out by a team at the University of Nice Sophia-Antipolis, and published in Psychological Science.