Category Archives: Recent Findings

Published ≤ 6 months ago

‘The Emotional Eye: Red Sclera as a Uniquely Human Cue of Emotion’ – Commentary

When I came across this paper by Provine et al. (2013), I wanted to write about the content the way I usually do, i.e., describe what was done and the main conclusions that were drawn. However, I soon found myself making notes more about the form than the content, criticising the paper. The authors investigated the effect of reddening the sclera of one or two eyes in photographs. They presented their participants with the images and asked them to rate them according six basic emotions (“anger, fear, sadness, disgust, happiness, and surprise”, p. 994).

First of all, I find the title of this article a tad misleading. It lacks a key word, in my opinion, and that is “valence”. The main finding presented is that the red sclera in humans seems to be a cue of emotional valence, rather than simply a cue of emotionality, indicating whether the emotion displayed is negative or positive (respectively, associated positively and negatively with “increased conjunctival blood flow”, p. 996).

Besides, the “uniquely human” aspect of the association between sclera colour and emotion was actually not addressed in the research; it was merely explained in the introduction. Again, I don’t think that it was incorrect to include the phrase in the title – it is partly what attracted me to download the article – but misleading.

Why these emotions and not others?

Onto the Introduction. Having a psychology background, I cannot fail to notice the lack of citations at the point where the authors list the six emotions they included in their study. They are ignoring a massive amount of research on emotions and the associated facial expressions. Even naming just one study by the famous Paul Ekman would have sufficed to show that they did not just pull these categories of emotions out of nowhere, and that they are giving credit where credit is due.

There is also no mention of either actual or possible gender differences in the perception of facial expressions of emotions. I think it is problematic as gender is later bluntly presented as an intergroup factor in the data analysis, yet the reason for its inclusion is not explained.

According to the Methods, the researchers used a pen and paper survey to collect data. I wonder whether they had trouble. In my experience, participants can be somewhat annoyed and tell you about errything that is wrong with the choices you made.

Alright, now for the Discussion. For the most part, I enjoyed it. Except maybe for what some might consider nit-picking; I say it is proper spelling.

A classic.

In this word, u is a consonant, not a vowel.

And finally…

...bootlicking much?

…bootlicking much?

Of course, it is not to say that Provine et al. (2013) is not a good article. I just enjoy pointing out shortcomings in other people’s work because it makes me feel better about myself ;^).

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Baby barn owls count

Being an animal, human or not, is not easy peasy. In order to survive and make lots of babies, one must get enough resources, such as food, territory, and mates (the sexual kind, of course). More often than not, this implies competing for those resources with others, especially conspecifics (members of the same species). So, to be successful and thrive, one needs to have certain strategies to deal with the competition. What have animals evolved for that?

In nature, resources are often limited; therefore, being able to correctly estimate the number of rivals you have can allow you to optimise your behaviour in a way that increases your chances of winning. For instance, you may choose to give up fighting if there are too many opponents.

In birds, the young depend, for their survival, entirely on the food provided by their parents. Yet, this food has to be shared with their siblings. This leads to competition between members of the same brood, explaining why nestlings beg to get the attention of their parents – they might get more food.

Because begging behaviours often come at a cost (e.g., predation; see Leech & Leonard, 1997), nestlings won’t do them if they are not too hungry. Ornithologists have discovered that the effort invested by nestlings in sib-sib competition (i.e., between siblings) can depend on their level of need, their ability to compete, or even the location of siblings in the nest. However, it is not known whether they modify their behaviour in response to the number of siblings present.

At the University of Lausanne, in Switzerland, researchers have investigated the numerical ability of nestling barn owls Tyto alba (Ruppli, Dreiss & Roulin, 2013). In these birds, parents bring to the nest small indivisible prey (often mammals) to feed their offspring. They do so at irregular time intervals so that their arrivals are unpredictable. In their absence, nestlings communicate vocally with each other – they negotiate – to determine who gets the food next time (Johnstone & Roulin, 2003).

Knowing that, the researchers devised a protocol to evaluate nestlings’ ability to count. They began by recording nestling calls emitted in nature from several broods. Then, they assembled those calls to create different combinations (playbacks) of both number of individuals and number of calls. They broadcasted these playbacks to singleton nestlings and measured, in particular, the number of calls that those “participants” emitted in response.

Ruppli et al 2013

Number of calls emitted by singleton nestlings (mean and standard error of mean) in response to varying number of playback individuals and varying playback call frequencies. The lines accompanied by one or more asterisks depict statistically significant differences, i.e., big enough that they’re probably not due to chance only (copied from Ruppli et al. 2013).

The results of this study show that nestlings called more or less depending not only on call frequency in the playback (number of stimuli), but also on the number of calling individuals. By the way, nestling barn owls seem to possess individual recognition abilities (pers. comm.), which is further supported by these results. According to the authors, it indicates that barn owl nestlings are capable of discriminating the number of competing individuals in the nest and using this information to adjust their own behaviour.

In short, this means that these birds possess a certain numerical ability, at least for small quantities in the context of sib-sib competition. It is not yet known whether this ability is maintained throughout life as the birds’ ecology changes.

This finding is important because it provides clues for understanding the function of numerical abilities and the factors which may have contributed to their evolution. In a way, it could lead to some insight into the emergence of mathematics in humans. Who knows, maybe they do not exist only as an instrument of torture for pupils/students…

Reference

Johnstone, R. A., & Roulin, Al. (2003). Sibling negotiation. Behavioral Ecology, 14(6), 780-786. doi: 10.1093/beheco/arg024

Leech, S. M. & Leonard, M. L. (1997). Begging and the risk of predation in nestling birds. Behavioral Ecology, 8(6), 644-646.

Ruppli, C. A., Dreiss, A. N., & Roulin, A. (2013). Nestling barn owls assess short-term variation in the amount of vocally competing siblings. Animal Cognition, 16(6), 1-8. doi: 10.1007/s10071-013-0634-y

PS: Many thanks to fellow grad student Tania Studer for her help in editing this post.

Follow-up on “Can you identify dogs’ emotions from their facial expressions?”

Last April, I published a post about dog’s facial expressions and how humans tend to be able to correctly classify the emotions they convey.

I included 2 photographs of my own dog, Charlie, each of them portraying him in a different condition. I used procedures to induce emotional states that were either positive or negative. Then I asked readers to rate the pictures in terms of the emotions they perceived were expressed.

Here are the method I used and the results of the ratings.

charlie1charlie2Charlie was asked to sit and stay put. He was then presented with an object – a treat (dog biscuit) to induce positive emotions, like happiness and interest, or a pair of tweezers (that I use to pull hair out from between his teeth and gum) to induce negative ones, like fear or sadness.

The photos were taken almost immediately after object presentation. The first on the left corresponds to the positive condition, whereas the second on the right corresponds to the negative condition.

Now, what did the respondents think?

First of all, I’d like to say that I’m amazed at how many responses I got: 94 in total!

Figure 1. Number of responses per emotion rating scale point

Figure 1. Number of responses per emotion rating scale point

Figure 1 demonstrates an overall floor effect – most responses were situated at the lower extreme of the rating scales. I seems like people found it easier to declare that a given emotion was absent rather than say they perceived one. This makes sense since I was not looking to elicit strong emotions. Had I done that, the responses might have been more equally distributed.

Figure 2. Basic emotion ratings in each of the conditions.

Figure 2. Basic emotion ratings in each of the conditions (sorry for the missing error bars – I could not add them without not messing up the graph).

The results show that, in both cases, people perceived Charlie to feel happy, sad, surprised, and fearful (Figure 2). This is interesting because it suggests that his face displays a mix of those emotions regardless of how he feels, as if his idiosyncratic facial features are always evocative of them like a human’s can be. Of course, a simplest explanation would be that the mildness of his affective state made it difficult to identify the emotion.

The major difference between the 2 conditions seems to lie in the 5th basic emotion – no one in the positive condition thought that Charlie felt angry.

Perhaps an element of his facial expression differed distinctly between the photos. If so, I’d say it was his ears. They either face forward or pulled back depending on the valence of the presented stimulus, i.e., positive or negative.

For a methodologically flawed little questionnaire, I think it yielded pretty interesting results. Thank you to all who rated!

Can you identify dogs’ emotions from their facial expressions?

Have you ever wondered what our canine friends think, or rather, feel? Being capable to recognise dogs’ emotions would surely be a useful ability, whether you are an owner concerned with you pet’s well-being or have an interest in avoiding being bitten by dogs in general. Do you believe to possess such an ability?

Source: MemeCenter

Researchers in the Unites States (Bloom & Friedman, 2013) found that humans can, in fact, classify rather accurately “the emotions conveyed by photographs of facial expressions of a dog”.

Even people with little to no experience with dogs could do that. The fact that learning was found to influence results only a little suggests that we might have somewhat of an inherent ability to recognise emotions in dogs. It is indeed possible that, during the domestication process, humans selected dogs whose affective states were more easily recognisable.

Bloom and Friedman partly drew from psychology and the affective sciences to develop their experiment, namely the work of the famous Paul Ekman (on whom the TV show ‘Lie to Me’ was based) and his colleagues. They created seven “behaviorally defined” scenarios to induce seven emotional states in the participating dog – happiness, sadness, surprise, disgust, anger, fear, and neutral, which served as a control condition for comparisons.

Inspired by their methods, I attempted to replicate two of those conditions. Below are the photographs thus obtained, accompanied by emotionality rating scales for each of the six basic emotions.

What I want YOU to do (yes, you, the person reading this post right now) is to rate the photographs. Each of them may contain one emotion or mixed emotions. Report what emotions, if any, you perceive as present, and to what degree. There is no right or wrong answer. You should choose only one option out of the five available for each emotion.

charlie1

charlie2

I am very curious to see how you guys interpret the facial expressions of my dog Charlie! In a future post, I will make sure to reveal the scenarios I used as well as the emotion I hoped to thus induce.

Ciao!

Reference:

Bloom, T., & Friedman, H. (2013). Classifying dogs’ (Canis familiaris) facial expressions from photographs. Behavioural Processes. doi: 10.1016/j.beproc.2013.02.010

Cognition in the wild, brought to you by the Rufous Hummingbird

Today’s date is 03/14 (that is, in the foolish countries that put the month number first), so it has become ‘Pi day‘. Few realise that it’s also Albert Einstein‘s birth date… and mine!

To celebrate, I’ve decided to write about my preferred animal behaviour topic (thus far): the study of cognition in the wild!

( ̄¬ ̄) Close enough

( ̄¬ ̄) Close enough

Why is it relevant? Because to understand the evolution of cognition in vertebrates, we need to examine animals’ abilities under natural conditions, where they face having to find food and mates, all the while evading all sorts of dangers. That way we can hope to identify some of the factors affecting the selection pressures at work. It is true that for some species, especially “smaller” ones, the line between the laboratory and the natural environment can get very blurry, if not inexistent. For “bigger” ones, though (like birds, mammals, and reptiles), the border is quite real. And those are the animals I’m interested in (again, thus far).

With doing something as messy as studying invisible processes in a rather uncontrollable environment comes great responsibility an assortiment of challenges. Let me list some of them as mentioned by Healy and Hurley (2013) in their review on ‘What hummingbirds can tell us about cognition in the wild’:

  • The participants may use different cues than in the lab, or use them differently, during tests;
  • Their ‘answers’ may not reflect the psychological dimension you’re trying to measure (an issue shared with all kinds of tests, I’m afraid);
  • How to make sure they’re motivated to actually participate?
  • What task to use?!?!! Meaning: what dimension are we going to choose to extrapolate their cognitive abilities??

Quite alarming, isn’t it? Well, it can be less so if you’re thoroughly prepared.

First, you need to find a “logistically amenable to testing” species which, in Healy and Hurley’s case, were rufous hummingbirds Selasphorus rufus. They focused on the males because those guys are territorial, so they fight off conspecifics from their patch, and feed frequently enough that nice amounts of data can be collected each day.

Rufous Hummingbird Selasphorus rufus. Credit: jessi.bryan on Flickr

Then, the species’ ecology should be such that you can formulate predictions about the abilities that might have been ‘encouraged’ by evolution, the same abilities that you’ll want to investigate. This requires, in particular, knowledge of their sensory ecology, of how they apprehend the world and might apprehend your experimental task.

I won’t go into too much detail here about the methods used by the authors and their colleagues in their experiments. They describe them rather well in their paper (see below for a direct link to it). But I will tell you this: it involves artificial flowers, arranged differently depending on the ability studied. As an example, in studying 3D spatial cognition:

… when flowers were presented on a vertical pole …, birds found it difficult to learn which one of five flowers was rewarded but when the flowers were presented along a diagonal pole, the birds were relatively quick to learn which was the rewarded flower (Flores Abreu, Hurley & Healy, 2013). Here it appears that the addition of a horizontal component to the flower’s location may have facilitated the learning of its vertical component.

Another set of findings they discuss are related to the use of colour, or lack thereof, in learning flowers’ refill rates – rufous hummingbirds use this cue “only when space is not relevant”. They also seem to possess a somewhat episodic-like memory, meaning they can simultaneously retain information on the what, the where and the when of an occurrence.

YES

YES

They conclude by stating that more data from comparative research is needed to continue figuring out the interaction between cognition and natural selection, especially the benefits of cognitive abilities as they pertain to particular animals and to their ecological demands.

This ‘required research’ business is very cool! Because an increased number of people understanding the necessity of it means that, maybe, just maybe, my own interests in the topic could one day neatly align with a supervisor’s and, who knows, some grants committees’…

Reference:

Healy, S. D., & Hurley, T. A. (2013). What hummingbirds can tell us about cognition in the wild. Comparative Cognition and Behavior Reviews, 8, 13-28. doi: 10.3819/ccbr.2013.80002 <– THAT’S THE DIRECT LINK

Salmon ACTUALLY use Earth’s magnetic field to find their way home

Five years ago, it was hypothesized that marine migrants, such as salmon and turtles, travelling long distances to reach their natal waters to spawn (a process known as natal homing) use geomagnetic cues to navigate to the correct area (Lohmann, Putman & Lohmann, 2008). Now, for the first time, there is empirical evidence to support this hypothesis.

Sockeye salmon Oncorhynchus nerka. Credit: Wikipedia.

Sockeye salmon Oncorhynchus nerka. Credit: Wikipedia

Adapted from Putman et al. 2013

Putman et al. (2013) analysed fisheries data spanning 56 years, from 1953 to 2008, that described the proportion of sockeye salmon Oncorhynchus nerka that took either the northern or the southern route to reach the mouth of the Fraser River, near Vancouver Island, Canada (see the above illustration). They examined whether these proportions were correlated with changes in magnetic field intensity and other environmental factors.

They found that, the more the magnetic field of a strait resembled the one of the Fraser River mouth, the higher the proportion of salmon that used it. It is as if they had previously imprinted on the magnetic field of the river, much like geese imprint on a parent some 13 to 16 hours after hatching, and were able to use this information years later during spawning migration.

The other significant factor affecting their itinerary was Sea Surface Temperature (SST). Years with higher SST were characterized by an increased propotion of salmon choosing the northern route, possibly because fish preferred colder waters.

Changes in magnetic field intensity, SST and the interaction between the two explain up to 66% of the variance in migratory route use.

This study employed a retrospective non-experimental design, which does have its shortcomings, including a multitude of possible confounding variables. Notwithstanding, these findings are crucial to understanding natal homing mechanisms and, as Putman et al. put it, “call for experiments on the navigation abilities of adult salmon as well as further investigation into the magnetic imprinting hypothesis”.

PS: I would like to thank my brother for drawing my attention to this study.

References:

Lohmann, K. J., Putman, N. F., & Lohmann, C. M. F. (2008). Geomagnetic imprinting: A unifying hypothesis for long-distance natal homing. Proceedings of the National Academy of Sciences, 105(49), 19096-19101. doi: 10.1073/pnas.0801859105

Putman, M. F., Lohmann, K. J., Putman, E. M., Quinn, T. P., Klimley, A. P., & Noakes, D. L. G. (2013). Evidence for geomagnetic imprinting as a homing mechanism in Pacific Salmon. Current Biology, 23, 1-5. doi: 10.1016/j.cub.2012.12.041

Giraff…also become conscious while selecting friends

The Bio Infos

giraff

giraff

giraff

Female giraffes choose their ‘friends’ carefully. Researchers found that female giraffes prefer to be in groups with particular peers and avoided others—their network, however, wasn’t based on home range overlap or kinship. This information, which also tells scientist how diseases spread and how individuals learn from one another, will help them develop better conservation programs

Reference: http://bit.ly/10SFAMD

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Reptilian Societies

Have you ever read (or watched) Dinotopia? It is a book (and TV) series about a land where dinosaurs never went extinct. Not only that, but they also managed to create a civilization where humans and “saurians” live together in relative harmony. What always fascinated me in Gurney‘s work was the idea of reptiles, in this case dinosaurs, manifesting social behaviour paralleling humans’. Unfortunately, reptiles have, in comparison to mammals and birds, been disregarded in vertebrate social behaviour research.

Another ctenosaura lizard (Costa Rica)

A Ctenosaura lizard (Costa Rica)

In their review, Doody, Burghardt and Dinets (2013) discuss the reasons behind this neglect. They describe how reptiles have traditionally been placed in the ‘non-social’ category of the ‘social–non-social’ dichotomy. According to them, this dichotomy is too simplistic and therefore deceptive as it fails to represent the variety of social systems in the animal kingdom. In fact, studying reptile social behaviour should help understand the mechanisms and evolution of complex social behaviour. The bias in research towards mammals and birds can be explained by the fact that it is easier to study “vertebrate groups whose communication systems are more salient to human sensory perception” (Doody et al. 2013, p. 96).

Besides, the inconspicuousness of reptiles and their nests creates an apparent absence of social behaviour in these animals, especially parental care. And let us not forget other human originated obstacles, such as the difficulty to get funding for such studies.

For some species, at least, social behaviour is observable in the egg stage. For example, pig-nosed turtle Carettochelys insculpta embryos make hatching happen faster when they sense vibrations coming from their siblings. Embryos of Nile crocodiles Crocodylus niloticus can adjust the synchronization of hatching and stimulate mothers by vocalizing. Parental care is rather rare, but tuataras Sphenodon punctatus and iguanas stay with the eggs for several days. Hatchling iguanas lacking packing parental care protect themselves using group vigilance.

Crocodilian mothers stay for the whole incubation period and beyond! They excavate and break the eggs, communicate vocally with their eggs and hatchlings, carry hatchlings to water, feed and protect them. Biparental care, which is the norm in vertebrates like canids and cichlids, has actually been recently documented in crocodilians (Brueggen, 2010, and Whitaker, 2007, cited by Doody et al. 2013).

Green iguana Iguana iguana lounging around (Costa Rica)

Green iguana Iguana iguana lounging around (Costa Rica)

Another pic of the same iguana, just because it's so gorgeous.

Another pic of the same iguana, just ’cause it’s so gorgeous.

Group of american crocodiles Crocodylus acutus resting (Costa Rica)

Group of american crocodiles Crocodylus acutus resting (Costa Rica)

American crocodile Crocodylus acutus going into the water (Costa Rica)

American crocodile going into the water (Costa Rica)

Green sea turtle Chelonia mydas (Madagascar)

Green sea turtle Chelonia mydas (Madagascar)

What about social behaviour beyond parental care? For one thing, snakes, lizards, turtles and crocodilians display conspicuous territoriality visible through the signals, postures and combats of males.

In addition, it is common for some lizards to form large and stable social groups. The ones formed by lizards of the genus Egernia show “kin recognition, inbreeding avoidance mechanisms, parental care, group antipredator behaviors and long-term social and genetic monogamy of up to 20 yr” (Doody et al. 2013, p. 98). Cooperative breeding occurs in broad-snouted caimans Caiman latirostris and other caimans and alligators as they form multi-parental crèches. In any case, much research is necessary to be able to correctly estimate the proportion of reptile species to live in groups.

Cooperative hunting is another example of an advanced behaviour not formally depicted. As you can see in this BBC video, banded sea kraits Laticauda colubrina are sea snakes that compensate for their slowness by hunting communally.

Alligators Alligator mississippiensis have also been observed feeding cooperatively (Dinets, 2010). They can gather in small areas where water depth does not exceed 50 cm and spend up to 6 hours circling the area and catching fish.

Common wall lizard capturing a butterfly (France)

Common wall lizard Podarcis muralis capturing a butterfly (France)

I should mention as well that reptiles have complex mating systems, which include polygyny, polyandry, monogamy and parthenogenesis, accompanied by varied courtship behaviours. Social play has, too, been recorded in crocodilians, lizards and turtles.

Perhaps, in real life, reptiles do not exactly parallel human social behaviour, but they are definitely not ‘non-social’. There is a lot more to learn about them and I am excited for what new information future research will bring.

DISCLAIMER: I am not a professional herpetologist, so I might have made mistakes in identifying the animals presented in the photographs. If you have spotted an error, please feel free to correct me in the comment section.

References:

Dinets, N. (2010). Nocturnal behaviour of american alligator (Alligator mississippiensis) in the wild during the mating season. Herpetological Bulletin, 111, 4-11. link

Doody, J. S., Burghardt, G., & Dinets, V. (2013). Breaking the social–non-social dichotomy: a role for reptiles in vertebrate social behavior research? Ethology, 119, 95-103. doi: 10.1111/eth.12047

Doody, J. S., Stewart, B., Camacho, C., & Christian, K. (2012). Good vibrations? Sibling embryos expedite hatching in a turtle. Animal Bheaviour, 83(3), 645-651. doi: 10.1016/j.anbehav.2011.12.006

Symonds, D. (Producer) & Brambilla, M. (Director). (2002/II). Dinotopia [TV series]. Worldwide: Hallmark Entertainment Distribution LLC.

Vergne, A. L., & Mathevon, N. (2008). Crocodile egg sounds signal hatching time. Current Biology, 18(12), R513-4. doi: 10.1016/j.cub.2008.04.011

Vergne, A. L., Pritz, M.B., & Mathevon. N. (2009). Acoustic communication in crocodilians: from behaviour to brain. Biological Reviews, 84, 391-411. doi: 10.1111/j.1469-185X.2009.00079.x

Dragonflies have some thinking abilities

The Bio Infos

Researchers in Australia have found evidence that dragonflies are capable of higher-level thought when hunting their prey. This is the first evidence that an invertebrate animal has brain cells capable of selective attention, something that has so far only been demonstrated in primates.

dragonflies

dragonflies

dragonflies

dragonflies

 

Reference: http://bit.ly/TkjaAp

 

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