The ability to reliably perceive the emotions of other people is vital for normal social functioning, and the human face is perhaps the strongest non-verbal cue that can be utilized when judging the emotional state of others (Ekman, 1965). The advantages of possessing this ability to recognise emotions, i.e., having emotional intelligence, include being able to respond to other people in an informed and appropriate manor, assisting in the accurate prediction of another individual’s future actions and additionally to facilitate efficient interpersonal behavior (Ekman, 1982; Izard, 1972; McArthur & Baron, 1983). In the current experiment the consistency with which emotions display by a human female face and a Pokémon character are investigated.
The current study employed 30 hand drawings of Pikachu, a first generation electric-type Pokémon character, depicting a range of emotions (images used with permission from the illustrator, bluekomadori [https://www.deviantart.com/bluekomadori]; based on the video game characters belonging to The Pokémon Company); see Fig. 1a for examples. Also, 30 photo-quality stimuli displaying a range of emotions, expressed by the same female model, were taken from the McGill Face Database (Schmidtmann et al., 2016); see Fig. 1b for examples. Ratings of arousal (i.e., the excitement level, ranging from high to low) and valence (i.e., pleasantness or unpleasantness) were obtained for each image using a similar method to Jennings et al. (2017). This method involved the participants viewing each image in turn in a random order (60 in total: 30 Pikachu and 30 of the human female from the McGill database). After each image was viewed (presentation time 500 ms) the participants’ task was to classify the emotion being displayed (i.e., not their internal emotional response elicited by the stimuli, but the emotion they perceived the figure to be displaying).
The classification was achieved via “pointing-and-clicking” the corresponding location, with a computer mouse, within the subsequently displayed 2-dimensional Arousal-Valence emotion space (Russell, 1980). The emotion space is depicted in Fig. 1c; note that the red words are for illustration only and were not visible during testing, they are supplied here for the reader to obtain the gist of the types of emotion different areas of the space represent. Data for 20 observers (14 females) was collected, aged 23±5 years (Mean±SD), using a MacBook Pro (Apple Inc.). The stimuli presentation and participant responses were obtained via the use of the PsychToolbox software (Brainard, 1997).
Figure 1. Panels (a) and (b) illustrate 3 exemplars of the Pokémon and human stimuli, respectively. Panel (b) shows the response grid displayed on each trial for classifications to be made within (note: the red wording was not visible during testing). Panels (d) and (e) show locations of perceived emotion in the human and Pokémon stimuli, respectively. Error bars present one standard error.
The calculated standard errors (SEs) serve as a measure of the classification agreement between observers for a given stimuli and were determined in both the arousal (vertical) and valence (horizontal) directions for both the Pokémon and human stimuli. These are presented as the error bars in Fig. 1d and 1e. The SEs were compared between the two stimulus types using independent t-tests for both the arousal and valence directions; no significant differences were revealed (Arousal: t(58)=-0.97, p=.34; and Valence: t(58)= 1.46, p=.15).
Effect sizes, i.e., Cohen’s d, were also determined; Arousal: d=0.06, and Valence: d=0.32, i.e., effect sizes were within the very small to small, and small to medium ranges, respectively (Cohen, 1988; Sawilowsky, 2009), again indicating a high degree of similarity in precision between the two stimuli classes. It is important to note that the analysis relied on comparing the variation (SEs) for each classified image (reflecting the agreement between participants) and not the absolute (x, y) coordinates within the space.
What could observers be utilizing in the images that produce such a high degree of agreement on each emotion expressed by each stimulus class? Is all the emotional information contained within the eyes? Levy et al. (2012) demonstrated that when observers make an eye movement to either a human with eyes located, as expected, within the face or non-human (i.e., a ‘monster’) that has eyes located somewhere other than the face (for example, the mythical Japanese Tenome that has its eyes located on the palms of his hands; Sekien, 1776) the observers’ eye movements are nevertheless made in both cases towards the eyes, i.e., there is something special about the eyes that capture attention wherever they are positioned. Schmidtmann et al. (2016) additionally showed that accuracy for identifying an emotion was equal when either an entire face or a restricted stimulus showing just the eyes was employed. The eyes of the Pikachu stimuli are simply black circles with a white “pupil”, however they can convey emotional information, for example, based on the positions of the pupil, the orientation of the eye lid, and by how much the eye is closed. It is hence plausible that arousal-valence ratings are made on the information extracted from only the eyes.
However, for the Pokémon stimuli Pikachu’s entire body is displayed on each trail, and it has been previous shown when emotional information from the face and body are simultaneously available, they can interact. This has the result of intensifying the emotion expressed by the face (de Gelder et al., 2015), as perceived facial emotions are biased towards the emotion expressed by the body (Meeren et al., 2005). It is therefore likely that holistic processing of the facial expression coupled with signals from Pikachu’s body language, i.e., posture, provide an additional input into the observers’ final arousal-valence rating.
Whatever the internal processes responsible for perceiving emotional content, the data points to a mechanism that allows the emotional states of human faces to be classified with a high precision across observers, consistent with previous emotion classification studies (e.g., Jennings et al., 2017). The data also reveals the possibility of a mechanism present in normal observers that can extract emotional information from the faces and/or bodies depicted in simple sketches, containing minimal fine detail, shading and colour variation, and use this information to facilitate the consistent classification of the emotional states expressed by characters from fantasy universes.
Brainard, D.H. (1997) The psychophysics toolbox. Spatial Vision 10: 433–436.
de Gelder, B.; de Borst, A.W.; Watson, R. (2015) The perception of emotion in body expressions. WIREs Cognitive Science 6: 149–158.
Ekman, P. (1965) Communication through nonverbal behavior: a source of information about an interpersonal relationship. In: Tomkins, S.S. & Izard, C.E. (Eds.) Affect, Cognition and Personality: Empirical Studies. Spinger, Oxford. Pp. 390–442.
Ekman, P. (1982) Emotion in the Human Face. Second Edition. Cambridge University Press, Cambridge.
Izard, C.E. (1972) Patterns of Emotion: a new analysis of anxiety and depression. Academic Press, New York.
Jennings, B.J.; Yu, Y.; Kingdom, F.A.A. (2017) The role of spatial frequency in emotional face classification. Attention, Perception & Psychophysics 79(6): 1573–1577.
Levy, J.; Foulsham, T.; Kingstone, A. (2013) Monsters are people too. Biology Letters 9(1): 20120850.
McArthur, L.Z. & Baron, R.M. (1983) Toward an ecological theory of social perception. Psychological Review 90(3): 215–238.
Meeren, H.K.; van Heijnsbergen, C.C.; de Gelder, B. (2005) Rapid perceptual integration of facial expression and emotional body language. Proceedings of the National Academy of Sciences 102: 16518–16523.
Russel, J.A. (1980) A circumplex model of affect. Journal of Personality and Social Psychology 39(6): 1161–1178.
Schmidtmann, G.; Sleiman, D.; Pollack, J.; Gold, I. (2016) Reading the mind in the blink of an eye – a novel database for facial expressions. Perception 45: 238–239.
Sekien, T. (1776) 画図百鬼夜行 [Gazu Hyakki yagyō; The Illustrated Night Parade of a Hundred Demons]. Maekawa Yahei, Japan.
About the Author
Dr. Ben Jennings is a vision scientist. His research psychophysically and electrophysiologically investigates colour and spatial vision, object recognition, emotions, and brain injury. His favourite Pokémon is Beldum.
“The system of life on this planet is so astoundingly complex that it was a long time before man even realized that it was a system at all and that it wasn’t something that was just there.” ―Douglas Adams, 1990
Douglas Noel Adams was born on 11 March 1952 in Cambridge, UK, and grew up to become one of geekdom’s most revered icons. Adams is the author of… Well, that is pretty obvious and I should not have to write this down, but I will nonetheless, just because I won’t be able to sleep well otherwise. So bear with me for a moment – here goes: Adams is the author of the trilogy The Hitchhiker’s Guide to the Galaxy, the self-proclaimed world’s largest trilogy, with five books in total.
However, unbeknownst to many of his fans, Adams was also an environmental activist. He spearheaded or participated in several conservation initiatives, such as Save the Rhino International. His history with conservation started in 1985, when the World Wide Fund for Nature (better known as WWF) and British newspaper The Observer partnered up, sending writers to visit endangered species to raise public awareness (BBC, 2014). Adams travelled to Madagascar in search of a lemur species, the aye-aye (Daubentonia madagascariensis). As he put it, “My role, and one for which I was entirely qualified, was to be an extremely ignorant non-zoologist to whom everything that happened would come as a complete surprise” (LCtS: p. 1).
In Madagascar Adams met not only weird lemurs, but also British zoologist Mark Carwardine. They enjoyed the experience and decided to travel the world to see other endangered animals. I mean, Adams and Carwardine travelled the world, not the lemurs; the lemurs stayed in Madagascar as far as anyone can tell. According to Carwardine, “We put a big map of the world on a wall, Douglas stuck a pin in everywhere he fancied going, I stuck a pin in where all the endangered animals were, and we made a journey out of every place that had two pins” (BBC, 2014).
Their travels resulted in Last Chance to See, a BBC radio documentary series that aired in the end of 1989. The companion book (by Adams & Carwardine, 1990, henceforth abbreviated as “LCtS”) was published in the following year (Fig. 1). As a matter of fact, Adams considered this book as his favorite work (Adams, 2005).
Despite Adams’s calling himself an “ignorant non-zoologist”, world-renowned evolutionary biologist Richard Dawkins politely disagreed, writing: “Douglas was not just knowledgeable about science. He didn’t just make jokes about science. He had the mind of a scientist, he mined science deeply and brought to the surface… humour, and a style of wit that was simultaneously literary and scientific, and uniquely his own” (Dawkins, 2009: p. xiii).
Last Chance to See describes Adam’s and Carwardine’s travels around the globe to see nearly-extinct species, such as the Amazonian manatee (Trichechus inunguis) and the northern white rhinoceros (Ceratotherium simum cottoni). As one could expect, nearly all the species are mammals, since most of the public are primarily concerned with cuddly and relatable species. I, however, will focus here on the only bird on their list that got an entire chapter for itself. And I’ll do that for various reasons: (1) I am not very normal, so I am not that fond of smelly mammals; (2) it is a success story and people like success stories; and (3) this is a very funny-looking bird, I promise you.
This bird is called kakapo.
Mark Carwardine first described the kakapo to Douglas Adams as “the world’s largest, fattest and least-able-to-fly parrot” (LCtS: p. 7). His description might seem a little disparaging at first, but it was meant in an affectionate way – you cannot help but smile when you see a kakapo. Besides, Carwardine’s description is actually spot-on (Fig. 2).
According to Adams, “[the] kakapo is a bird out of time. If you look one in its large, round, greeny-brown face, it has a look of serenely innocent incomprehension that makes you want to hug it and tell it that everything will be all right” (LCtS: p. 108).
The kakapo (or kākāpō, in Māori or Te Reo spelling) is a nocturnal flightless bird and its face resemble that of an owl, with the eyes positioned more to the front. For this reason, it is also known as owl-parrot or night parrot. Kakapos have green feathers, speckled with black and yellow (Fig. 3).
Furthermore, kakapos are solitary birds, have a polygynous lek mating system (don’t panic, I’ll explain that later), lack male parental care, and breed in irregular intervals (with gaps of 2 to 7 years; Powlesland et al., 2006). Kakapos are so unique that ornithologists classified the species in its own family: Strigopidae. They are the very first lineage to have branched out of the parrot group (the Order Psittaciformes). Even their closest “relatives”, the kaka and the kea (also from New Zealand), are already considered to be very distinct from kakapos.
Being such an ancient lineage of parrots, researchers consider that it could have split off the rest of the parrot groups when New Zealand got separated from the what is now Australia and Antarctica around 80 million years ago (Gibbs, 2016). All the southern landmasses had been previously joined in the supercontinent Gondwana, which was made up of South America, Africa, India, Antarctica, Australia and Zealandia (Fig. 4) and was by that time finishing its separation.
This break up left Zealandia with no mammals and a bird “paradise” island started to take shape. It is considered that the kakapo followed the trend of oceanic island bird lineages (where nasty mammals are not present) to evolve larger and flightless forms (Powlesland et al., 2006). For instance, that happened with the lineages of the dodo, moa, and elephant bird.
I cannot overstate how weird kakapos are for a parrot – or for a bird, actually. Adams considered the kakapo the strangest and most intriguing of all the creatures he saw during his travels with Carwardine (LCtS: p. 105). So I’ll illustrate that by highlighting some aspects of its biology that are of broader interest or peculiar weirdness. If you, however, are looking for a complete guide to the species’ biology, do take a look at the work of Powlesland et al. (2006).
We already covered that kakapos are nocturnal and flightless, and thus have good hearing and sense of smell, alongside massive legs and feet to walk around and climb trees. Yes, they do not fly, but do climb trees to feed. Evolution works in mysterious ways, it seems. Elliot (2017) wrote: “They often leap from trees and flap their wings, but at best manage a controlled plummet.” I prefer, however, the way Douglas Adams put it: “it seems that not only has the kakapo forgotten how to fly, but it has forgotten that it has forgotten how to fly. Apparently a seriously worried kakapo will sometimes run up a tree and jump out of it, whereupon it flies like a brick and lands in a graceless heap on the ground” (LCtS: p. 109).
It seems kakapos are not able to follow the suggestion of the Hitchhiker’s Guide: “There is an art, it says, or rather, a knack to flying. The knack lies in learning how to throw yourself at the ground and miss. (…) Clearly, it is this second part, the missing, which presents the difficulties” (Adams, 1982). Kakapos just constantly fail to miss the ground.
Overall, kakapos are quite large birds, weighing around 2 kg, but males may weigh up to 4 kg and be 40% larger than females (Eason et al., 2006; Elliot, 2017). Their life span is unknown, but is estimated at 60 to 90 years (Department of Conservation, 2018a, 2018b).
Kakapos are vegetarian and eat almost every possible parts of plants. In fact, they only breed in years with a good abundance of fruit (Cockrem, 2006; Elliot, 2017). In their current habitat, kakapo reproduction is tied with that of the rimu (Dacrydium cupressinum), an evergreen coniferous tree of the podocarp family (Fig. 5). These plants bloom together every 2 to 4 years (sometimes it takes more); the kakapos must wait for the rimu because they depend on its “fruits” (Fig. 6) to feed the chicks (Cockrem, 2006; Ballance, 2010).
Unlike any other parrot, kakapos are lek breeders. This behavior is common for other groups of birds and even other animals, though. It consists in males gathering relatively close to each other and starting a competition to show off to females. Birds can do this mainly by song or dance (or both), but might also include somersaults and flying maneuvers. Each female will chose the best performer (in their opinion at least) and successful males typically mate with more than one female during a single season.
Male kakapos sing to attract females. Or rather, they do something akin to “Pink Floyd studio out-takes” (LCtS: p. 111). The most common type of call produced by kakapos is called booming. This is a low-frequency (<100 Hz) resonant call, which can be heard up to 5 km away (Merton et al., 1984; Higgins, 1999). To produce this sound, male kakapos fill up internal air sacs; they can inflate until they look like a fluffy watermelon (Figs. 7, 8). Adams described the sound as a heartbeat, a powerful throb you felt before actually hearing it; and this gave the title to the kakapo’s own chapter in LCtS: “Heartbeats in the Night”.
Booming also serves to indicate the male’s overall location to the female. Once they are close by, males can produce a sharp metallic “ching” call to enable females to pinpoint their exact location (Powlesland et al., 2006). A good place to hear kakapo booming and chinging is New Zealand Birds Online (http://nzbirdsonline. org.nz/).
The female nests on the ground, either on a spot covered by dense vegetation or in natural cavities (Elliot, 2017). Kakapos usually lay 2 to 4 eggs and the female raise the chicks alone (Fig. 9; Cockrem, 2006; Powlesland et al., 2006). Young birds leave the nest within 2 to 3 months, but remain close to their mother’s home range until they are 6.5 to 8.5 months old (Farrimond et al, 2006; Powlesland et al., 2006).
So how do we summarize kakapos? Adams gives us a nice idea: “The kakapo (…) pursues its own eccentricities rather industriously and modestly. If you ask anybody who has worked with kakapos to describe them, they tend to use words like ‘innocent’ and ‘solemn’, even when it’s leaping helplessly out of a tree. This I find immensely appealing” (LCtS: p. 121).
Presently, the most famous kakapo is Sirocco, who became a YouTube star after he tried to mate with Carwardine’s head during the filming of the Last Chance to See TV series (Carwardine, 2010). Today, Sirocco is 21 years old and is the official “spokesbird” for conservation in New Zealand (Department of Conservation, 2018b), a title given to him by then Prime Minister John Key.
Kakapos were present in New Zealand long before humans arrived there: some subfossil bones have been dated from 2500 years ago (Wood, 2006). They were very common and lived throughout both the North and South Islands (Tipa, 2006), with few natural enemies. They were successful in their pre-human environment, but that was soon to change.
Polynesian settlers arrived in Aotearoa between 1200 and 1300 CE (Wilmshurst et al., 2010) and became known as the Māori. As typical of all humans, they brought domestic/pest species with them: dogs and rats.
As many island species, kakapos were only concerned with their known immediate predators; these mostly harmless birds were thus unprepared for a wave of invaders. Kakapos have the strategy of staying perfectly still when facing danger, which works fine against predators that rely on sight. However, this had little effect against dogs, which hunt by scent. The parrots were hunted for food and ornamentation (for instance, the Māori used the feathers in cloaks; Tipa, 2006) and the population declined. Polynesian rats also played a major role, preying upon defenseless kakapo eggs and chicks.
European settlers arrived on the 19th century and, as one might expect, colonization (and new mammalian predators, such as cats and mustelids) accelerated the species’ decline. The Europeans also brought naturalists, who collected specimens for study at museums (Fig. 10). British zoologist George Robert Gray officially named the kakapo Strigops habroptilus in 1845. Later naturalists (some already born in New Zealand) went further, observing live parrots in the wild and studying their natural history.
Already in the 1890’s, naturalists became aware that the species was heading towards extinction, so the first efforts in conservation (transferring animals to islands in Fiordland; Fig. 11) were undertaken (Hill & Hill, 1987). They failed and eventually the species fade out from the thoughts of New Zealanders, being considered extinct or nearly so (Ballance, 2010).
BUT DON’T PANIC
That lasted until the work of Williams (1956), which summarized all knowledge about the kakapo and brought it back to the spotlight. With this renewed interest, expeditions were formed to find the species in the southernmost reaches of New Zealand.
A serious take on conservation efforts started again in the 1970’s, when a population of around 200 kakapos was found on Stewart Island (Fig. 11; Powlesland et al., 2006). A new process of translocation and monitoring then began. During the 1980s and 1990s, the animals were all moved to predator-free islands: Codfish, Maud and Little Barrier (Fig. 11; Elliot, 2017). When Adams and Carwardine visited Codfish Island in 1992, there were only around 40 kakapos left (Ballance, 2010; Carwardine, 2010).
However, things started to look brighter after a review in the management of the species (Elliot et al., 2001). A strong and focused policy and full support of the government were essential during the decades since (Jansen, 2006). The kakapo population started to recover and can now be considered one of the greatest successes among global conservation programs – and a good example of how our species can, in fact, clean up after its own mess.
The last report, from June 2017, counted a total of 154 birds (Elliot, 2017), a number exceeding previous population simulations (Elliot, 2005). Recovering the kakapo from the brink of extinction was a feat, but more challenges remain. Presently, the species is considered as “critically endangered” according to the IUCN’s Red List (BirdLife International, 2016). Although this seems better, it is good to remember that this is just one step away from the “extinct in the wild” status in this classification scheme (which the kakapo held during two issues of the Red List in the mid-1990s). Presently, kakapos only survives on offshore islands and there is still lot of work to be done until we have a viable, and self-sustaining population that does not need human management.
Maybe just panic a little bit…
The kakapo is not the only endangered species in the New Zealand – everyone has heard about kiwis, at least. So what about all the other threatened species, birds and otherwise, in the country? Jansen (2006: 190) ominously wrote: “While extinction of kakapo is now less likely than 10 years ago, the future of the 600+ New Zealand species listed as acutely and chronically threatened (…) and that presently do not receive any management is by no means secure.” So yes, there is still a lot of work to be done.
But why should we care if some species go extinct? Why should we strive so much to save them? Carwardine (LCtS: p. 205) gave what Dawkins (2009) considered to be the typical explanations for business-minded humans: (1) we mess with the environment, everything go haywire, and that ultimately affects our survival, and (2) living beings have their uses as food, drugs, etc. However, Carwardine then presented his preferred explanation, one more typical of scientists and that we say to each other over coffee: we try to save them because they are cool. Or, as Carwardine put it: “There is one last reason for caring, and I believe no other is necessary. It is certainly the reason why so many people have devoted their lives to protecting the likes of rhinos, parakeets, kakapos and dolphins. And it is simply this: the world would be a poorer, darker, lonelier place without them” (LCtS: p. 206).
“Up until that point it hadn’t really clicked with man that an animal could just cease to exist. It was as if we hadn’t realised that if we kill something, it simply won’t be there anymore. Ever. As a result of the extinction of the dodo we are sadder and wiser.” ―Douglas Adams, 1990
Adams, D. (1982) Life, the Universe and Everything. Pan Books, London.
Adams, D. (2005) The Salmon of Doubt: Hitchhiking the Galaxy One Last Time. William Heinemann, London.
Adams, D. & Carwardine, M. (1990) Last Chance to See. William Heinemann, London. [Edition used here: 2009, by Arrow Books, London.]
Ballance, A. (2010) Kakapo: Rescued from the Brink of Extinction. Craig Potton, Nelson.
Elliott, G.P.; Jansen, P.W.; Merton, D.M. (2001) Intensive management of a critically endangered species: the kakapo. Biological Conservation 99: 121–133.
Farrimond, M.; Elliott, G.P.; Clout, M.N. (2006) Growth and fledging of kakapo. Notornis 53: 112–115.
Gibbs, G. (2016) Ghosts of Gondwana: The History of Life in New Zealand. Fully Revised Edition. Potton & Burton, Nelson.
Jansen, P.W. (2006) Kakapo recovery: the basis of decision-making. Notornis 53: 184–190.
Higgins, P.J. (1999) Handbook of Australian, New Zealand and Antarctic Birds. Vol. 4: Parrots to Dollarbird. Oxford University Press, Melbourne.
Hill, S. & Hill, J. (1987) Richard Henry of Resolution Island: a Biography. John McIndoe, Dunedin.
Merton, D.V.; Morris, R.D.; Atkinson, I.A.E. (1984) Lek behaviour in a parrot: the Kakapo Strigops habroptilus of New Zealand. Ibis 126: 277–283.
Powlesland, R.G.; Cockrem, J.F.; Merton, D.V. (2006) A parrot apart: the natural history of the kakapo (Strigops habroptilus) and the context of its conservation management. Notornis 53: 3–26.
Tipa, R. (2006) Kakapo in Maori lore. Notornis 53: 193–194.
Williams, G.R. (1956) The kakapo (Strigops habroptilus, Gray): a review and re-appraisal of a near-extinct species. Notornis 7: 29–56.
Wilmshurst, J.M.; Hunt, T.L.; Lipo, C.P.; Anderson, A.J. (2011) High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia. PNAS 108(5): 1815–1820.
Wood, J.R. (2006) Subfossil kakapo (Strigops habroptilus) remains from near Gibraltar Rock, Cromwell Gorge, Central Otago, New Zealand. Notornis 53: 191–193.
I am very grateful to Colin Miskelly, Dylan van Winkel, the Department of Conservation, and the Museum of New Zealand Te Papa Tongarewa for allowing the usage of their photographs herein.
ABOUT THE AUTHOR
Dr. Rodrigo Salvador is a biologist specializing in the classification and evolution of land snails. Yes, you might say, that has nothing to do with kakapos. But it so happens that the universe conspires to keep him entangled with bird work. As a scientist, he learned with Douglas Adams that knowing the right question is sometimes more important than knowing the answer.
 Or six, if you count And Another Thing… by Eoin Colfer (2009).
 Later, in 1992, a CD-ROM set was published, with photos and audio of Douglas Adams reading the book. In 2009, BBC released a TV series of Last Chance to See, in which British comedian Stephen Fry took the place of the late Adams.
 However, he soon changed the tone to blame flying birds instead: “There is something gripping about the idea that this creature has actually given up doing something that virtually every human being has yearned to do since the very first of us looked upwards. I think I find other birds rather irritating for the cocky ease with which they flit through the air as if it was nothing” (LCtS: p. 120).
As a mild-mannered reporter, Clark Kent is able to blend into human society without drawing much attention to himself. Although he utilises several methods of disguise (clothing, posture, hair style), perhaps his most famous is a simple pair of glasses (see Figure 1). We know that wearing glasses can make you look more educated and intelligent (e.g., Hellström & Tekle, 1994), but for Superman, the goal is primarily to hide his true identity. Of course, one of the cornerstones of enjoying superhero fiction is that we suspend our disbelief and try to ignore the obvious questions (for example, how useful or plausible is it that Squirrel Girl can communicate with and understand squirrels?!). However, the scientist inside us sometimes breaks through and we are given the opportunity to investigate. Here, we tackle the question that comic book fans have been asking for decades – could Superman really hide his identity using a pair of glasses?
Figure 1. Clark Kent’s transformation into Superman. [Image downloaded from Flickr; labelled CC BY 2.0.]
Photos of faces appear on almost all official forms of identification, from passports and driving licences to university staff and student cards. We have this intuition that our face is a good way to identify us, but a growing body of evidence suggests otherwise. Of course, if we consider the people we know personally (friends, family, partners), it’s almost impossible to find a picture of them that you wouldn’t recognise. Even in their passport photos, which could be up to ten years old in the UK, you would probably recognise them straight away. Studies have shown that we can even recognise people we know from very degraded images, such as CCTV footage (Burton et al., 1999). Therefore, it’s no surprise that the presence or absence of a pair of glasses wouldn’t stop you from being able to recognise your sister or husband. This amazing tolerance for the way a familiar person’s face can vary across different photos leads us to think we are good at recognising all faces. In fact, we are significantly worse when asked to consider unfamiliar people’s faces (e.g., Clutterbuck & Johnston, 2002, 2004), even when the photos are taken from real university ID cards (Bindemann & Sandford, 2011).
A common task used in psychology studies to examine photo-ID-style face identification is a face matching task. Typically, participants are shown two images side-by-side and asked whether the photos show the same person or not. Usually, only half of the image pairs show the same person in both photos, although depicted in different poses, lighting, expressions, etc. In the remaining image pairs, the two photos show two different but similar-looking people (e.g., two young, brunette women).
Participants do very well (often perfectly) at the task when they are familiar with the person (or one of the people) pictured, but are much worse when they are unfamiliar with the people (see Figure 2). When we see two photos of someone we know, we even seem to be blind to how difficult the task would be for people who don’t know that person, over-estimating other people’s performance with faces we recognise (Ritchie et al., 2015).
So why are we so bad at this task for people we are unfamiliar with? To answer this, we need to start with why we are so good at it for people we are familiar with.
Figure 2. Example face matching task images. Top: Two photos of the same familiar person. Despite changes in pose, lighting, and expression, it is seems easy to tell that the two photos show the same person. [Images downloaded from Wikimedia Commons; labelled CC BY-SA 3.0 (left) and CC BY 2.0 (right).] Bottom: Two photos of the same unfamiliar person. It is more difficult to tell that the two images show the same person when we are not familiar with them. [The person pictured has given consent for her images to appear here.]
While we are getting to know someone’s face, we experience a lot of variation in their appearance. We see them from different angles, in different lighting, wearing their hair in different ways, etc. This variability seems to be important for learning new people (Murphy et al., 2015; Ritchie & Burton, 2016). But this same variability gets in the way when we are presented with two images of an unfamiliar person – the photographs can look very different and this might lead us to think they show two different people.
Why is any of this actually important? Coming back to the example of photo-ID, try to consider the task given to Jenny, a fictional passport controller. Jenny’s job is to decide whether the person standing in front of her is the same person as the one pictured in the passport they hand over. The passport photo may be up to ten years old, and more importantly, Jenny has never seen this person before. We know already that this unfamiliar face matching task is a hard one for regular people who do not do this as a routine part of their job, but researchers have also shown that even passport controllers do not outperform students on this sort of task (White et al., 2014b).
Now let’s get back to Superman and his glasses. In our new study (Kramer & Ritchie, 2016), we showed participants pairs of images where both wore glasses, pairs where neither face wore glasses, and ‘mixed’ pairs where one wore glasses and one did not. Half of the pairs in each of these image conditions showed the same person, and half depicted two different (but similar-looking) people. Participants were simply asked to indicate whether they thought the images were of the same person or two different people. Importantly, we only used images of people who were unfamiliar to our participants (and we confirmed this at the end of the study). In addition, all our images were collected from Google Image searches and showed natural variation in pose, lighting, etc. (see Figure 3 for an example of face images that naturally vary).
Figure 3. Images of Brandon J. Routh with and without glasses. The image on the left shows him as Clark Kent, in the film Superman Returns (2006); the image on the right is more recent and familiar to fans of the TV series Arrow (2012–present) and DC’sLegends of Tomorrow (2016–present). Of course, in our study, we only used images of unfamiliar people. [Left image downloaded from Flickr; labelled CC BY-NC-SA 2.0. Right image downloaded from Wikimedia Commons; labelled CC BY 2.0.]
When neither image wore glasses, accuracy (percentage correct) was 80.9%, and when both images wore glasses, accuracy was 79.6%. Statistically, performance in these two conditions did not differ, and these levels of accuracy are in line with those reported elsewhere (e.g., Burton et al., 2010). However, in the ‘mixed’ image condition, where one face wore glasses and the other did not, accuracy dropped to 74%. This drop in performance (although it sounds quite small) was statistically lower than in the ‘no glasses’ and ‘glasses’ conditions. This means that we can be confident that our ‘mixed’ condition really did make people worse at the task. For this reason, Superman may have hit upon a disguise that isn’t just easy but might actually work. By simply donning a pair of glasses, he may well make it that little bit harder for strangers to tell that he also doubles as a reporter living among them.
This effect of glasses might be hugely problematic for photo-ID in security settings. In the USA, people are allowed to wear glasses in their passport photos but may not be wearing glasses when they go through passport control. The 6% drop in accuracy found in our study, which could also be phrased as an increase in misidentifications, quickly scales up to thousands of potential mistakes when we consider the vast numbers of people going through passport control every day.
This all seems fairly bleak when it comes to photo-ID so many researchers have been working on ways that we might improve the situation. One recent suggestion has been to provide multiple images (White et al., 2014a; Menon et al., 2015). By including several photographs as reference images for comparison, instead of just the one typically found on IDs, scientists have produced significant improvements in accuracy. This is an area of ongoing investigations and other types of improvements to photo-ID will continue to be explored.
Bindemann, M. & Sandford, A. (2011) Me, myself, and I: Different recognition rates for three photo-IDs of the same person. Perception 40: 625–627.
Burton, A.M.; Wilson, S.; Cowan, M.; Bruce, V. (1999) Face recognition in poor quality video: Evidence from security surveillance. Psychological Science 10: 243–248.
Burton, A.M.; White, D.; McNeill, A. (2010) The Glasgow Face Matching Test. Behavior Research Methods 42: 286–291.
Clutterbuck, R. & Johnston, R.A. (2002) Exploring levels of face familiarity by using an indirect face-matching measure. Perception 31: 985–994.
Clutterbuck, R. & Johnston, R.A. (2004) Matching as an index of face familiarity. Visual Cognition 11(7): 857–869.
Hellström, A. & Tekle, J. (1994) Person perception through facial photographs: Effects of glasses, hair, and beard on judgments of occupation and personal qualities. European Journal of Social Psychology 24: 693–705.
Kramer, R.S.S. & Ritchie, K.L. (2016) Disguising Superman: How glasses affect unfamiliar face matching. Applied Cognitive Psychology: advance online publication (DOI: 10.1002/acp.3261). Available from: http://onlinelibrary.wiley.com/doi/10.1002/acp.3261/full (Date of access: 14/Sep/2016).
Menon, N.; White, D.; Kemp, R.I. (2015) Variation in photos of the same face drives improvements in identity verification. Perception 44(11): 1332-1341.
Murphy, J.; Ipser, A.; Gaigg, S.B.; Cook, R. (2015) Exemplar variance supports robust learning of facial identity. Journal of Experimental Psychology: Human Perception and Performance 41: 577–581.
Ritchie, K.L.; Smith, F.G.; Jenkins, R.; Bindemann, M.; White, D.; Burton, A.M. (2015) Viewers base estimates of face matching accuracy on their own familiarity: Explaining the photo-ID paradox. Cognition 141: 161–169.
White, D.; Burton, A.M.; Jenkins, R.; Kemp, R.I. (2014a) Redesigning photo-ID to improve unfamiliar face matching performance. Journal of Experimental Psychology: Applied 20(2): 166–173.
White, D.; Kemp, R.I.; Jenkins, R.; Matheson, M.; Burton, A.M. (2014b) Passport Officers’ errors in face matching. PLoS ONE 9(8): e103510.
ABOUT THE AUTHORS
Dr. Kay Ritchie wears glasses on a daily basis. But is adamant that she has no secret identity…
Dr. Robin Kramer frequently collaborates with Bruce Wayne in various crime-fighting adventures but states for the record that the current research is neither funded by Wayne Enterprises nor does it represent any ulterior motives of Batman.