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Films trick our senses in many ways. Most fundamentally, there’s the illusion of motion as “moving pictures” don’t really move at all. Static images shown at a rate of 24 frames per second can give the semblance of motion. Slower frame rates tend to make movements appear choppy or jittery. But film advancing at about 24 frames per second gives us a sufficient impression of fluid motion.
However, birds–such as pigeons–have a much higher threshold for detecting movement. A bird’s visual system is keenly sensitive to moving stimuli as this is essential to their survival. Whether swooping down to snatch live prey, fleeing from a predator, or zeroing in on a nest for a precise landing, birds must rely on their fine-tuned ability to hone in on moving targets. So the frame rate at which most of our films are shown is far too slow for birds to perceive continuous motion. Their threshold of visual processing exceeds the standard frame rate, allowing them to see component frames … and the illusion of motion pictures would be broken.
If a pigeon had been roosting in the theater where 19th century crowds first gaped at the Lumière Brothers’ steam train looming towards them, it may have been less than impressed — especially as early silent films were often played at only 16 frames per second.
Even a film shown at today’s industry standard of 24 frames per second would most likely look like a series of flashing slides to a pigeon. We’re mesmerized by Marilyn Monroe’s white skirts billowing over the subway grate in The Seven-Year Itch, but a pigeon may see something more like a slide show of the skirt in frozen increments.
Further, most humans cannot distinguish individual lights flashed at 60 cycles per second, perceiving instead a single continuous beam of light. This gives an impression of constant light while watching a film (despite the shutter actually shutting out light several times per frame). But birds have much higher critical flicker-fusion frequency, such as 90-100 cycles per second or higher (e.g., Lisney et al., 2011). So while humans do not perceive the flicker in a movie, a pigeon may see flashes like strobelights along with the jumpy frames of Marilyn’s airborne skirt.
One of the creepiest scenes in Hitchcock’s The Birds shows Melanie (Tippi Hedren) smoking on a bench in a school playground while birds are flocking on a jungle gym behind her. She finally spots a lone bird flying overhead and turns around to discover every rung of the jungle gym crowded with large black birds. Actually, Hitchcock used cardboard cut-outs for most of the “birds” on the jungle gym, figuring that most people would not notice these stationary objects if interspersed with live birds.
Birds in a school playground in Hitchcock’s (1964) The Birds
Indeed, the illusion works on most of us. We are also often tricked by illusory “crowds” in films–made of real people and dummies, or multiple images of the same people patched together to make a “crowd”. However birds are especially observant of the movement of other birds–and combined with the much faster ‘refresh rate’ of the avian visual system (as their visual information is “updated” more frequently than humans)–the jungle gym scene would not likely fool any birds.
Studies suggest that birds do perceive some information via video images (using video at 30 frames per second). For instance, a video of wild chickens feeding elicits feeding in birds of the same species (McQuoid & Galef, 1993); videos showing a hawk or raccoon elicit aerial and ground alarm calls respectively in roosters (Evans, Evans, and Marler, 1993); and video images of female pigeons elicit courtship displays in male pigeons (Shimizu, 1998).
So birds seem to pick up some information from video images, at a somewhat higher frame rate and screen-refresh rate than film–though color may be distorted (Wright & Cumming, 1971), and gaps in movement and flicker are likely perceived (Lea & Dittrich, 1999). These discrepancies would be much more pronounced for moving images on cinematic film.
A fine-tuned visual system gives birds of prey an advantage when pursuing a fast-moving target. And it allows pigeons those few extra seconds to peck at grubs and seeds–and flap away at the last moment possible when your car approaches.
Feral Rock Dove. Photograph by Andrew D. Wilson. CC BY-SA 2.5 via Wikimedia Commons.
Nut their super-efficient processing of moving stimuli would make the cinematic experience as we know it less than spellbinding for the birds.
In conclusion: it’s interesting to note that film relies on certain limitations or imperfections of the human perceptual system for its magic to work!
Siu-Lan Tan is Associate Professor of Psychology at Kalamazoo College in Michigan, USA. She is primary editor of The Psychology of Music in Multimedia (Oxford University Press 2013), the first book consolidating the research on the role of music in film, television, video games, and computers. A version of this article also appears on Psychology Today. Siu-Lan Tan also has her own blog, What Shapes Film? Read her previous blog posts.
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Visual illusions, such as the rabbit-duck (shown below) and café wall are fascinating because they remind us of the discrepancy between perception and reality. But our knowledge of such illusions has been largely limited to studying humans.
That is now changing. There is mounting evidence that other animals can fall prey to the same illusions. Understanding whether these illusions arise in different brains could help us understand how evolution shapes visual perception.
For neuroscientists and psychologists, illusions not only reveal how visual scenes are interpreted and mentally reconstructed, they also highlight constraints in our perception. They can take hundreds of different forms and can affect our perception of size, motion, colour, brightness, 3D form and much more.
Artists, architects and designers have used illusions for centuries to distort our perception. Some of the most common types of illusory percepts are those that affect the impression of size, length, or distance. For example, Ancient Greek architects designed columns for buildings so that they tapered and narrowed towards the top, creating the impression of a taller building when viewed from the ground. This type of illusion is called forced perspective, commonly used in ornamental gardens and stage design to make scenes appear larger or smaller.
As visual processing needs to be both rapid and generally accurate, the brain constantly uses shortcuts and makes assumptions about the world that can, in some cases, be misleading. For example, the brain uses assumptions and the visual information surrounding an object (such as light level and presence of shadows) to adjust the perception of colour accordingly.
Known as colour constancy, this perceptual process can be illustrated by the illusion of the coloured tiles. Both squares with asterisks are of the same colour, but the square on top of the cube in direct light appears brown whereas the square on the side in shadow appears orange, because the brain adjusts colour perception based on light conditions.
These illusions are the result of visual processes shaped by evolution. Using that process may have been once beneficial (or still is), but it also allows our brains to be tricked. If it happens to humans, then it might happen to other animals too. And, if animals are tricked by the same illusions, then perhaps revealing why a different evolutionary path leads to the same visual process might help us understand why evolution favours this development.
The idea that animal colouration might appear illusory was raised more than 100 years ago by American artist and naturalist Abbott Thayer and his son Gerald. Thayer was aware of the “optical tricks” used by artists and he argued that animal colouration could similarly create special effects, allowing animals with gaudy colouration to apparently become invisible.
In a recent review of animal illusions (and other sensory forms of manipulation), we found evidence in support of Thayer’s original ideas. Although the evidence is only recently emerging, it seems, like humans, animals can perceive and create a range of visual illusions.
Animals use visual signals (such as their colour patterns) for many purposes, including finding a mate and avoiding being eaten. Illusions can play a role in many of these scenarios.
Great bowerbirds could be the ultimate illusory artists. For example, their males construct forced perspective illusions to make them more attractive to mates. Similar to Greek architects, this illusion may affect the female’s perception of size.
Animals may also change their perceived size by changing their social surroundings. Female fiddler crabs prefer to mate with large-clawed males. When a male has two smaller clawed males on either side of him he is more attractive to a female (because he looks relatively larger) than if he was surrounded by two larger clawed males.
This effect is known as the Ebbinghaus illusion, and suggests that males may easily manipulate their perceived attractiveness by surrounding themselves with less attractive rivals. However, there is not yet any evidence that male fiddler crabs actively move to court near smaller males.
We still know very little about how non-human animals process visual information so the perceptual effects of many illusions remains untested. There is variation among species in terms of how illusions are perceived, highlighting that every species occupies its own unique perceptual world with different sets of rules and constraints. But the 19th Century physiologist Johannes Purkinje was onto something when he said: “Deceptions of the senses are the truths of perception.”
In the past 50 years, scientists have become aware that the sensory abilities of animals can be radically different from our own. Visual illusions (and those in the non-visual senses) are a crucial tool for determining what perceptual assumptions animals make about the world around them.
Bringing together significant work on all aspects of the subject, Behavioral Ecology is broad-based and covers both empirical and theoretical approaches. Studies on the whole range of behaving organisms, including plants, invertebrates, vertebrates, and humans, are welcomed.
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Image credit: Duck-Rabbit illusion, by Jastrow, J. (1899). Public domain via Wikimedia Commons.<
Wonderful! Superb animation, brilliantly spoof old style British narration. If you’ve got the full 6 minutes to spare this is great for a really good giggle. It’s from the minds of Aardman Animation of Wallace and Gromit and many others fame. You know it’s going to be quality animation and you know it’s going to have a corking script.
Awesome Water Slide and Jump
I don’t care if this is faked or not, it’s still great to watch, and I’ll bet my aunties prize begonias that you’ll hit that play button again for another look. If this is genuine, then that’s one brave, brave man there. I’d have liked to have seen the preparation work for this, I bet there’s some good out takes there somewhere. Come on guys, let’s see how you worked it out. Crash test dummies?
Sheep LED art
I found this one just really, really fascinating, as well as being quite funny. Hope you enjoy it too. Having become an honorary Welshman after marrying my lovely, lovely wife, I enjoyed passing this round to my English brethren. This must have taken an absolute age to get right, and all for a couple of minutes of fame on YouTube. There’s nowt so queer as folk…….
Happy New Year
A cracking take on the three little pigs story, with a superb twist. I love it. My kids love it too. Great little catchy tune and a real sense of urgency from the pigs. I’m not sure where it originated from, but it certainly bears some resemblance to The Dark Side, and it definitely has that kind of humour running through its theme. Enjoy.
Moving Dragon Illusion
These are great. There are a few more like this dotted around YouTube, if you search under optical illusions you’ll find them. The ones with people’s faces can be quite odd, but so very realistic. They are amazing. I don’t know who thought of it or came across it first, but they are brilliant.
Wonderful! Superb animation, brilliantly spoof old style British narration. If you’ve got the full 6 minutes to spare this is great for a really good giggle. It’s from the minds of Aardman Animation of Wallace and Gromit and many others fame. You know it’s going to be quality animation and you know it’s going to have a corking script.
Awesome Water Slide and Jump
I don’t care if this is faked or not, it’s still great to watch, and I’ll bet my aunties prize begonias that you’ll hit that play button again for another look. If this is genuine, then that’s one brave, brave man there. I’d have liked to have seen the preparation work for this, I bet there’s some good out takes there somewhere. Come on guys, let’s see how you worked it out. Crash test dummies?
Sheep LED art
I found this one just really, really fascinating, as well as being quite funny. Hope you enjoy it too. Having become an honorary Welshman after marrying my lovely, lovely wife, I enjoyed passing this round to my English brethren. This must have taken an absolute age to get right, and all for a couple of minutes of fame on YouTube. There’s nowt so queer as folk…….
Happy New Year
A cracking take on the three little pigs story, with a superb twist. I love it. My kids love it too. Great little catchy tune and a real sense of urgency from the pigs. I’m not sure where it originated from, but it certainly bears some resemblance to The Dark Side, and it definitely has that kind of humour running through its theme. Enjoy.
Moving Dragon Illusion
These are great. There are a few more like this dotted around YouTube, if you search under optical illusions you’ll find them. The ones with people’s faces can be quite odd, but so very realistic. They are amazing. I don’t know who thought of it or came across it first, but they are brilliant.
