What Your Brain Sees May Not Be What You See

National Geographic:

According to research published in the journal Psychological Science, our brains pick up on images that we never consciously perceive.

Volunteers were shown a series of black-and-white images while hooked up to an EEG device that recorded their brain activity. Each image was shown for just under two-tenths of a second. Then the subject pressed a button to indicate if the object was something familiar (like a turtle or telephone) or novel (a random shape that they didn’t recognize).

The task was simple enough, but there was one more layer that the subjects didn’t know about: On the outside of some of the random shapes, a recognizable image was hidden in the background—like the seahorse silhouette in the picture above.

The team wanted to know what the brain does with images that are right in front our eyes but that we don’t consciously see, like this seahorse. That’s where the EEG testing comes in. About 400 milliseconds after subjects looked at the silhouette, a wave called a N400 was recorded by the EEG device, said lead researcher Jay Sanguinetti, a doctoral candidate at the University of Arizona. The appearance of that brainwave suggests that the brain is processing something meaningful.

So even though the majority of the subjects said they didn’t notice the background images at all (some didn’t believe they were there even when shown them after the study, notes Sanguinetti), their brains still produced the N400 wave.

Read the whole story: National Geographic