In addition to seeing objects that are directly in view, we also represent objects that are merely implied (e.g., by occlusion, motion, and other cues). What can imply the presence of an object? Here, we explored (in three preregistered experiments; N = 360 adults) the role of physical interaction in creating impressions of objects that are not actually present. After seeing an actor collide with an invisible wall or step onto an invisible box, participants gave facilitated responses to actual, visible surfaces that appeared where the implied wall or box had been—a Stroop-like pattern of facilitation and interference that suggested automatic inferences about the relevant implied surfaces. Follow-up experiments ruled out confounding geometric cues and anticipatory responses. We suggest that physical interactions can trigger representations of the participating surfaces such that we automatically infer the presence of objects implied only by their physical consequences.
The "Stroop-like pattern" the authors mention refers to the Stroop effect, wherein a test subject is given an image where there are the names of various colors represented in different colors of ink, but they don't match -- e.g. the word "green" is written in red ink. The subject is then asked to state, as quickly as possible, the colors of each word, ignoring the word that's actually written and focusing only on the ink color.
It's quite difficult to do. You are attempting to force your brain to ignore the textual information (the words themselves) and focus only on the colors, but the two interfere with each other so much -- and we're so geared to getting information by reading text -- that to do it accurately, most people have to concentrate and slow down, and still they make mistakes.
Here, the implied surfaces the mime is creating generate such a strong illusion that if they don't correspond with a visual indicator of where the surfaces are, we tend to believe the mime rather than the indicator. For example, in one test, volunteers were asked to state whether a line superimposed on a video clip of a mime was horizontal or vertical. In some of the clips the line was oriented the same way, and in the same position, as the "surface" the mime was creating; in other cases, they didn't agree. In the latter case, test subjects were routinely tripped up -- they tended to answer based on the (invisible) surface the mime's actions indicated rather than the (visible) marker they were supposed to be focusing on."Very quickly people realize that the mime is misleading them, and that there is no actual connection between what the person does and the type of line that appears," said study co-author Patrick Little, in an interview with Science Daily. "They think, 'I should ignore this thing because it's getting in my way', but they can't. That's the key. It seems like our minds can't help but represent the surface that the mime is interacting with -- even when we don't want to."