Words: Deepanjana Biswas (she/her)
There is no pure truth and impure lie, only multifaceted matter beckoning the mind’s curious perception.
I recall being 11 and seeing the capricious conjuring that is the duck-rabbit illusion in our school’s psychology exhibition. It was unfathomable to me that an image could shapeshift in a wisp of a moment – almost magical. Once a rabbit, and then a duck: a slip of vision falters in the wake of wonder. Over the years, this magic slipped from the crevices of a fanciful imagination to the technical realm of optical illusions (psychology textbooks tend to axe the whimsy within you), but nevertheless it remains a fascinating topic to bring up at inappropriate times.
Illusions, in the Oxford English Dictionary, vary in meanings to convey a common sense of deception – an experience of unreality, if you will. The word’s etymological roots can be traced to the French word ‘illude’, which roughly means to trick, cheat, or evade, before narrowing into the scope of sensory experience once borrowed into Middle English. One of the earliest uses of this word dates back to 1340, in Rolle’s Prose Treat, where he warns that angels’ songs can often be an ‘illusion’ of the Devil. Both the literary canon and the cultural eye treat illusions as an opposition to the objective truth. There is the real, and there is the illusory: a dichotomous existence confined within clipped fences.
Optical illusions, however, oppose this. There is no unreality, as whatever is seen within them truly exists in that given point of time – a superposition of perception. Whether it be a duck or a rabbit, a face or a vase (like in the Rubin’s vase illusion), both images are real; there is no moral precedence of one over the other, making optical illusions a perceptual experience rather than that of consciousness. Yet, these two states can only ever coexist in parallel, never to be seen (at least to the untrained eye) simultaneously. This occurs due to something called “bistable perception”: a phenomenon in which an ambiguous stimulus offers two different interpretations, with only one interpretation being visually perceived at a given time, and the other being suppressed by our brains.
A stimulus can be anything in the immediate environment which elicits a sensory response from us, and with ambiguous stimuli, these responses are often uncertain. This causes us to deploy our attention again, switching focus to form a new mental image or “percept”, thus allowing us to view two different images. Above is one computational account for “bistable perception”, with another being that of Bayesian inference. Bayesian inference is a theorem of statistical probability which auto-updates itself with new evidence, and the brain is believed to use this process to change its perceptual predictions. Upon seeing a “bistable” image, the following happens:
A sensory input is briefly suppressed during eye movements (scientifically called saccades) → Using this Bayesian model of probability, the brain reweighs which sensory input is more trustworthy → The interpretation of the image switches.
Though not as whimsical as the illusory deception which dissipates like dreamlike smoke, it’s a worthy contender to consider!
While it is said that art imitates life, life also seems to imitate science. Our culture is filled with instances of “bistable perception” beyond the stuffy interiors of psychology exhibitions. Say, for example, that the ambiguous stimulus of a national flag in a bedroom holds multiple states of meaning within its existence. Yet, upon observation, it can only exist in one state depending on the mind of the viewer, perhaps representing a:
- patriot
- far-right nationalist
- strange fellow with a penchant for collecting flags
Other states of meaning are temporarily suppressed as our brain uses predictive probability to assign meaning based on past input. A multivariate object is thus changed upon observation.
You might also remember me using the word ‘superposition’ a while back. You may wonder what this word, locked within the mystifying realms of quantum mechanics, has to do with our humble optical illusion? Well, firstly, what is superposition? It’s a principle which proposes that quantum systems can exist simultaneously in multiple states until observation. Observation (such as taking measurements of quantum properties) causes these systems to fall into a singular state. Sounds familiar, right? It’s reminiscent of “bistable images”, which can only exist as one visual upon observation, despite holding two visual states.
Thus, the dualistic nature of optical illusions, through the lens of quanta, shows that dualism does not equal negation. There is no pure truth and impure lie, only multifaceted matter beckoning the mind’s curious perception. Whether it be the meaning we make of objects or the images we see, matter is quite literally changed by the mind’s perception of it. Perhaps, even now, the magic of optical illusions is not all lost. Begetting an end with some words from the Lord’s Prayer of WhiteFerrari by Frank Ocean, ‘Mind over matter is magic!’
