Strange Illusion Demonstrates How the Human Brain Mess With Time to Maintain Our Expectations


People frequently declare, "I saw it with my own eyes." 

The assumption is that something must have happened because we perceived it.

However, what we see may be impacted by a variety of factors, including our own expectations and preconceptions, as demonstrated by a peculiar new experiment.

Researchers have uncovered a "novel perceptual illusion" that successfully reorders the apparent temporal order of events in a series, according to a recent research.

"Can seemingly higher-level expectations, such as [presumed] causality, affect the order in which we experience events occurring?" "Is our perception of time and temporal order a faithful reflection of what happens in the world (or at least what arrives at our retina) or can seemingly higher-level expectations, such as [presumed] causality, affect the order in which we experience events occurring?" Writes  team of researchers leads by author and experimental psychologist Christos Bechlivanidis from University College London.

The researchers presented over 600 people an animation in which a fairly simple 'ABC' sequence of events appears to occur: an A square collides with a B square, which then collides with a C square.

The animation, in fact, showed the C square beginning to move before the B square impacted with it (known as 'ACB'), and even somewhat – 150 milliseconds – before the B square began to move after colliding with A.

Researchers discovered that when the ACB animation is exhibited, many people remember the chain of events as ABC, with their sense of temporal order being impacted by their expectations of causality, according to a prior study co-authored by Bechlivanidis.

"We were initially interested in reverse causation, and if people may perceive causes occurring after their consequences in particular cases," Bechlivanidis told PsyPost.

"After a few studies, we rapidly found that the expectation of a temporal orientation (that causes come before consequences) is so powerful that individuals insist on seeing the causes first even if the order is reversed."

One theory for the occurrence is that people may misremember what happened when they subsequently recover the memory after observing the sequence of events - dubbed the'memory hypothesis' by researchers.



Indication of flash timing based on perception of the sequence. (Bechlivanidis et al., Psychological Science, 2022)

Bechlivanidis and his colleagues presented participants the ACB animation again, but this time they recorded their replies in real time, asking them to indicate the times when B and C start moving by matching their timing with a short flash on the screen.

Participants would properly report the timing in real-time if the memory theory was valid, as seen in the image above. Despite multiple viewings, the experiment revealed that respondents thought B moved faster than it actually did, whereas C appeared to move slower.

"When seeing the reordered ACB series, participants genuinely experience B happening sooner and C happening later, at timings that approach the entire temporal displacement required to change the ACB sequence into the causal ABC sequence," the researchers write in their report.

"When one of the items was concealed, such large displacements were not detected. The online reversal of temporal order is consequently caused by the erroneous causal environment."

While much underlying this perceptual illusion remains unknown, the researchers claim that our capacity to objectively detect the time of a signal is overtaken by assumptions we make about the timing of its transmission, regardless of the source of the signals.

Strong causal expectations overcome incoming information from a visual signal in this example, as the domino-like physics of an expected ABC chain of events overrides our capacity to see what's really going on.

It's unclear how deep the illusion extends, but it's just the latest example of how our vision is influenced in unexpected ways as the brain struggles to cope with the constant barrage of visual information we're assaulted with.

The findings are reported in Psychological Science.