"I saw it with my own eyes" is something people often say. The implication is that since we saw something, it must have happened.
A strange new experiment shows how easy it is for our own expectations and assumptions to affect our perception.
Scientists discovered a novel perceptual illusion that reorders the perceived temporal order of events.
Is our perception of time and temporal order a faithful reflection of what happens in the world or can seemingly higher-level expectations, such as causality, affect the order in which we experience events occurring?
In a series of experiments, the researchers showed over 600 participants an animation in which an A square collides with a B square, which in turn collides with a C square.
The animation showed the C square beginning to move before the B square began to move.
Researchers found that when the ACB animation is shown, many people remember the chain of events as ABC, with their perception of temporal order seemingly being influenced by their expectations of causality.
We became interested in backwards causality and whether people can perceive causes after their effects.
After running a few experiments, we realized that the expectation of a temporal direction is so strong that even if we reverse the order, people will insist to have seen the causes happening first.
One explanation for the phenomenon is that people may be misremembering what occurred when they later retrieve the memory after seeing the chain of events.
Indication of flash timing based on perception of the sequence. (Bechlivanidis et al., Psychological Science, 2022)
In the new experiments, the team recorded the participants responses in real-time, asking them to indicate the moments when B and C begin to move, by timing their timing with a brief flash.
The participants would indicate the timing accurately if the memory hypothesis were correct. Despite repeated viewings, the experiment showed that people actually perceive B moving earlier than C does.
The researchers explain in their paper that when watching the reordered ACB sequence, participants actually perceive B happening earlier and C happening later, in total approach, the temporal displacement necessary to turn the ACB sequence into the ABC one.
Displacements of such magnitude were not observed when one of the objects was hidden. The online reversal of temporal order is caused by the illusory causality.
The researchers say our ability to objectively perceive the timing of a signal is superseded by our ability to infer the timing of its transmission, regardless of the nature of the signals.
The domino-like physics of an assumed ABC chain of events makes it difficult for us to see what is really happening.
As for how deep the illusion goes remains to be seen, but it's just the latest evidence of the surprising ways our perception is affected, as the brain tries to juggle the non-stop flood of visual information we're bombarded with.
The findings are reported in a journal.
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