Much of 20th Century philosophy is marked by a belief in the fundamental, ontological primacy of language and words. Figures like Ludwig Wittgenstein and Jacques Derrida submit that thinking is lingual, and that without language there can be no thought at all, much less a world to perceive.

New research from Yale University and the University of Wisconsin-Madison suggests that the dominance of language may be more than a philosophical concept. In a new study, they show that verbal stimuli can effectively alter the way we perceive the world, making us see things that aren’t there, LiveScience reports.

“Some people want to argue that vision is in some sense objective, an objective view of reality,” said study author Gary Lupyan, an assistant professor of psychology at the University of Wisconsin-Madison. However, “language alters some pretty fundamental visual processes.”

For the study, Lupyan and co-author Emily Ward of Yale University enrolled 20 students in an experiment with continuous flash suppression – a visual phenomenon in which modulating stimuli visible to one eye overrides and suppresses a weak, static stimulus visible to the other. Special 3D glasses determine what either eye sees or doesn’t see.  

With their left eyes, students saw meaningless disturbance patterns.

With their right eyes, they regularly “saw” brief, flashing images, which were immediately suppressed by the stimuli perceived by the left.

Half of the time, the image flashing before the right eye was paired with a relevant verbal cue – a “label.”

"Some of the cues they heard were correct, sometimes incorrect," Lupyan explains.

The subjects were then asked to describe the suppressed images.

“If the label was correct, they were more likely to see it if was actually there,” he continued. “If you heard the word ‘kangaroo,’ you were more likely to see a kangaroo.”

Read More: Why 83% Of Radiologists Couldn't See The Gorilla

Even though their minds kept them from seeing consciously the flashing images, the verbal cue allowed students to register and visualize the otherwise suppressed stimuli.

“We hypothesize that when information associated with verbal labels matches stimulus-driven activity, language can provide a boost to perception, propelling an otherwise invisible image into awareness,” Lupyan and Ward wrote in the study.

The findings suggest that perception may be more subjective and erratic than most of us would like to think.

Source: Gary Lupyan and Emily J. Ward. “Language can boost otherwise unseen objects into visual awareness.” PNAS 2013 ; published ahead of print August 12, 2013, doi:10.1073/pnas.1303312110