The ‘Continuity Illusion’- Is it Real or an Illusion?
Reality vs. Illusion series…[Part 2]
Next time we watch a YouTube video, a movie, or a flipbook animation, unknowingly, we might be under a brain phenomenon known as the ‘continuity illusion.’ The moving images we see on the screen are a series of static frames being played rapidly. Let’s call it the rapid static frame (RSF) movement. If asked, we would deny being so deluded at face value. That’s because the continuity illusion would have already invaded our brain system. Our brain perceives the RSF movement as a continuous, smooth motion instead of a flickering type above a certain rate/speed called the Flicker Fusion Frequency (FFF) threshold. This threshold varies amongst species [1].
Recent research shows that when the brain is subjected to RSF movement below the FFF threshold, it shows interest in tracking the moving frames as it can detect the change. But when subjected above the FFF threshold, there is a suppression in neural or brain activity, indicating the person’s brain is no longer concerned with keeping track of the frame movement. This is due to a neural structure called ‘Superior Colliculus’ (SC), which decides not to process the visual stimulus (information) above that threshold, considering it as not new or noteworthy, resulting in just a continuous motion [1].
Remember watching the blades of the ceiling fan overhead picking up speed? As the speed increases, our brain stops keeping track of the exact movement of the blades. We just get a blurred vision of the fast-moving blades. That’s again the ‘continuity illusion’ at work.
It’s not just the story of our brain. Our senses equally have a specific detection range. Any information falling only in that range gets detected, and the rest is simply filtered out. That’s the reason, unlike bees, we don’t usually see ultraviolent light; we are deaf to noises beyond a specific range, and we don’t sense Earth’s magnetic field, unlike turtles and wolves [2].
Wondering why this happens? Well, Scientists inform us that if our senses and the brain were to take every detail of the objective information, we would be overwhelmed- information overload. The brain simply edits them out. Data compression is going on, simplifying the information content to function effectively [2].
So, whether it’s a movie or the blades of the fan we watch, our brain presents us with only a snapshot of information [2]. Is the perception that results from this info (snapshot) an illusion, or is there some reality in it? Let’s dive a bit deep to find out…
Interpretation:
All our five senses (visual-sight, auditory-sound, tactile-touch, olfactory-smell, and gustation-taste) are well equipped within a limited range to detect variations or changes happening in the environment corresponding to these five fields. Let’s call these variations the change phenomenon. After these sensory modalities detect the change, the information is further passed to the brain, where it is processed, and a perception is felt [3][4].
Any normal human can detect at least two types of changes in an obvious way that falls within its detection range:
- ‘Change phenomenon’ occurring in the spatiotemporal field (spacetime or geometrical/physical domain)
- The rate or speed at which the phenomenon is occurring.
For example, when the fan at rest starts rotating as we switch it on, we can easily detect the blades start changing their position in a circular motion. We also get a feel of speed, so we can say whether the fan is moving slowly or fast.
We all must have been through the experience of playing some part of the same movie or video at slow and fast speeds. Whether it’s the moving fan or the playing video, our brain perceives a continuous motion above the FFF threshold. But what is the information content of that continuous event?
After a bit of introspection, we can easily conclude that we are well aware of
- spatiotemporal changes of the event and
- the rate/speed at which it is occurring
We may not be able to give precise mathematical figures to our observation, but that’s not strictly needed in the ordinary course for our biological survival. What we know for sure is that the blades and the movie characters are moving at a certain speed. The brain captures both of the information. That’s the information content. It exactly corresponds with the objective physical occurrence of the event- the physical reality.
Yes, there may be many details that we might be missing, like we would fail to gaze at a spot on the fan blade as it picks up speed. Nevertheless, the snapshot of information that is picked up has real-time value. The info (snapshot) that the brain/mind can encode, process, and represent as a perception carries real information about the ‘change phenomenon’ of the objective world.
Therefore, I think perceiving reality based on the ‘information snapshot’ can’t be termed an illusion as long as its corresponding physical occurrence is a reality. Missing out on many details from a real physical occurrence does not make a perception an illusion. Instead, the snapshot can be termed as useful information aptly needed for biological and social survival.
We miss out for a reason!!
The fan’s movement at a particular speed can give us useful information on how dangerous it could be to poke our hand into that blurred vision.
Conclusion:
A real illusion is detected when a mismatch exists between perception and physical reality [5]. In my previous publication [6], I discussed this based on usability. The more we can detect the mismatch (otherwise known as illusoriness), the more our adaptive fitness is enhanced [5]. Putting it another way, research shows that:
“…it is not biologically useful to perceive everything as being illusory” [5].
To survive, the organism needs to differentiate reality from illusion effectively. The illusoriness can be naturally offered by nature or devised by another organism through predator-prey interactions.
“…if a prey perceives the illusoriness then it survives; conversely, if a predator perceives the illusoriness, its hunting can succeed” [5].
As per the interpretation, we found no mismatch in the information content between the perceptual and physical domains in the case of ‘continuity illusion’. Thus, I suggest not seeing it as an illusion but as a perceptual reality that has its usefulness.
Perceiving reality as ‘reality’ and illusion as ‘illusion’ can be equally useful for survival.
Finally, adding another layer to my reality vs illusion series, I hope some realness still holds its ground in us in a useful way if that can be a marker for ‘reality’…
Please feel free to reflect and comment on it. Looking forward to your feedback.
References:
- Gil, R. et al., (2024). “Rat superior colliculus encodes the transition between static and dynamic vision modes” by Rita Gil, Mafalda Valente and Noam Shemesh, 12 February 2024, Nature Communications.
DOI: 10.1038/s41467–024–44934–8; URL = https://scitechdaily.com/cinema-in-the-mind-the-neuroscience-behind-the-continuity-illusion/ - Lu, D. et al., (2020). URL = https://www.newscientist.com/article/mg24532670-800-what-you-experience-may-not-exist-inside-the-strange-truth-of-reality/
- Hanson-Baiden, J. (2022). How is Reality Constructed in the Brain?. News-Medical. Retrieved on February 12, 2024 from https://www.news-medical.net/health/How-is-Reality-Constructed-in-the-Brain.aspx.
- Privitera, A. J. (2024). Sensation and perception. In R. Biswas-Diener & E. Diener (Eds), Noba textbook series: Psychology. Champaign, IL: DEF publishers. URL = https://nobaproject.com/modules/sensation-and-perception#apa
- Pinna, B. et al., (2018). Illusion and Illusoriness of Color and Coloration. J. Imaging 2018, 4, 30. https://doi.org/10.3390/jimaging4020030
- Patnaik, A. (2024). URL = https://medium.com/@anilpatnaik.re/subjective-and-objective-modelling-of-life-80744b451d05
