An exciting announcement

A few mImageonths ago I was given the exciting offer of joining the team over at Scientific American on a new blog network, Scientific American MIND. From now on, all my articles will be over there at my new website. I’ll leave this site up for archive articles for the moment, but if these get transferred at some point I’ll shut it down. I never thought when I started writing here a couple years ago that it would lead to something like this, and a lot of that is due to the support from friends and readers of this site, so thanks, and I hope you continue to read my articles over at Scientific American. 

 

Drugs and error bars

I’ve been away from writing here for a while, as recently I’ve been stuck into a very different type of writing – finishing up my thesis for my PhD. One of the things that prompted me back into the blogging world was my reaction to the recent channel 4 show, ‘Drugs Live: the Ecstacy Trial

Now, I’m not going to discuss the ethics of taking illegal drugs on television, as this has already been well-covered. Instead, I wanted to draw attention to what to some might seem a much smaller point, but one that I feel represents a much larger issue throughout the reporting of science in the media. This post is much broader than my usual articles, but is relevant to animal behaviour, which, as a popular topic presented by the media, is often misrepresented in this way.

First, check out this graph from the show:

This seems to show that people invested more money (in computer-simulated faces) when they had taken ecstacy (MDMA) than when they had not (the control), and that this effect increased from one to eight days… but does it really? This graph doesn’t tell us this.

What I’m getting at here is that, to show whether these bars actually differ from each other, we need to see what are called ‘error bars’. Error bars are a way of showing visually how varied the measurements you’ve taken actually are. For example, if I stood on Oxford street and stopped 1000 people and asked them if I could count their fingers, if people let me do this and didn’t just look at me strangely before backing away, it is likely that I would find that the average number of fingers was 10 (or just under, as it’s probably more likely that someone would have lost a finger than have an extra one). However, it’s highly likely that most of the people I’d sampled would have 10 fingers. Because of this small variation in finger number, if I were to draw this on a graph, the error bar would be small.

If, on the other hand (no pun intended, really), I were to stop another 1000 people in the street and count the number of pointless items they had in their wallets, I might find that I also get an average of 10, but that this time there would be much more variation: a lot of tidy, organised (or sociopathic as I like to call them) types would have zero pointless items, whereas other people might have dozens of scrap bits of paper, receipts going back to the 1980s, and rewards cards to shops they didn’t even know existed. This time the error bars would be massive.

By putting error bars on a graph we can see how much variation there is in the data we’re looking at, and more importantly, visually assess how likely it is that the averages of different groups actually differ from each other.

As an example, this graph (of data I just made up) shows that  men drink more beer than women (on average 20 rather than 15 a week; the purple bars). However, people in the UK do not eat more pies than people in the US (the green bars). Even though the average numbers are the same (15 beers drunk by women, 15 pies eaten in the US and 20 beers drunk by men and 20 pies eaten in the UK), the error bars tell us that the data are very different from each other. In the case of the number of pies eaten, there is a lot of variation in the data, with some people in the UK and the US eating very few pies, and some eating lots, most likely those located in Manchester. Because there is so much variation in the data within each of these groups (UK and US), we cannot tell for sure whether the fact that the average is more in the UK than the US is a real finding, or just do to chance.

Going back to the ‘Drugs Live: the Ecstacy Trial’, as none of their graphs had error bars on them, we cannot be sure that any of the differences that we seem to see are actually there or not. In short, the graphs are pretty pointless.

On the drugs science website David Nutt, Val Curran and Robin Carhart-Harris wrote that they had originally included error bars (and p-values) on the graphs, but that Channel 4 removed them for clarity. This is somewhat ironic, as in doing this, they inadvertently made the results less clear to interpret. Apparently Channel 4 felt that an explanation would be ‘difficult’ for a general audience. I think that Channel 4 should not patronise their audiences. People like to be challenged and discover things that may not be clear at first; it’s why people continue to watch murder mysteries. Even if the programme did not have enough time to explain what error bars are, I do not think that people would have found the graphs harder to interpret with them present, and it might even lead to people going to google and finding out what they are for themselves.

I think the more the scientific process is made accessible to people the better, and a good way of doing this is through television programmes like this one. As a study that was both doing original work, and on a topic that many people are interested in, it seems perfect for television. My complaint here is not aimed specifically at Channel 4, but at the presentation of science more generally. The more people are given the tools for understanding how experiments are designed, carried out and then interpreted (using statistics as a tool), the better the communication between scientists and everyone else (including lawmakers) will be.

 

 

 

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If you’re keen to know more about statistics beyond the error bar, I came across this great blog the other day.

Liebster Award

I recently received a Liebster Blog Award from Kimberly Gerson, author of the blog Endless Forms Most Beautiful. I really appreciate her taking the time to read some of my articles, it’s always nice to know people take pleasure from what essentially is me taking pleasure from someone else’s hard work.

The Liebster Blog Award is based on peer recognition, and in that light there are rules that go along with it. Most importantly, recipients have to pass on the love:

1. Show thanks to the blogger who gave you the award by linking back to them.
2. Reveal your top five picks and let them know by leaving a comment on their blog.
3. Post the award on your blog.
4. Bask in the love from some of the most supportive people on the internet—other writers and artists.
5. And best of all – have fun and spread the karma.

Five blogs I would like to draw other’s attention to are the following:

1) Animal Wise, by Paul Norris. Paul and I started writing around the same time and I think between him and I we’ve got animal behaviour pretty much covered (with him covering the vast majority that is). He writes about a lot of the newest findings in animal behaviour, and covers a wide range of extremely interesting topics (but I would say that!)

2) Dog Spies, by Julie Hecht. Julie’s blog on dog science & sorting out the fact from fiction is very funny and easy to read, but all based in nice solid science.

3) The Thoughtful Animal, Jason Goldman, hardly needs a shout out from me. But his blog was one of the first I started reading, and I have stuck with for good reason – his articles are thorough always leave me feeling like I have learned a lot.

4) A Brain Scientist’s take on writing, by Livia Blackburne. As I am also approaching the end of my PhD, I am extremely impressed at how Livia Blackburne is finishing her one in neuroscience, whilst also keeping up an extremely interesting blog, not to mention writing a book or two. She covers science, literature and just generally interesting stuff about the world. A must read for those of you who have not stumbled across it yet.

5) Finally, for something completely different: Dave Macleod‘s blog. I imagine it’s only climbers that read this blog, but for those of you who do not climb and are interested at what the human body & mind are capable of at the most extreme, it is definitely worth a look. Dave has (unknowingly) helped me with my technique, psych and injuries relating to climbing.

Thanks again to Kimberly Gerson.

What are dogs trying to tell us?

In shows like Lassie, I was always impressed at the amount of information a dog was able to convey to a human: ‘What’s that, Lassie? A little girl trapped in a building that you tried to reach but then couldn’t owing to the fire that caught alight to the fence surrounding it?’

I never owned a dog myself, so I assumed this lack of understanding of dog-talk was down to some inadequacy on my part. However, a recent study has looked into exactly what it is that dogs do convey when communicating with humans with some surprising findings.

We know that dogs are able to understand a lot of what we say to them. A border collie, ‘Rico’, learned an impressive 200 human words.  As well as spoken commands, dogs also understand a lot of gestures, such as pointing or even a glance from a human.

We also know that dogs are able to convey certain types of information to humans. When food is hidden in a place that a dog knows about, but the human doesn’t, dogs are very good at showing the human where this might be (through a lot of barking, running about, jumping around etc.)

We humans communicate to inform others of information we think they may not know. From an early age, children are able to assess whether other individuals know what they themselves know, and inform them only when necessary. Indeed, sharing knowledge with others that they already know is seen as somewhat of social faux pas (as someone should inform older family members who insist on repeating such knowledge again and again). We do this even when sharing such information has no direct benefit to ourselves, and only helps the person we’re informing.

But can dogs do this? A recent study using forty pet dogs looked to see whether they would not only request an object that they were interested in, but also communicate to a human information about an object she wanted.

Firstly the dog was put in a room with an experimenter and experienced one of four possible conditions. Some dogs got to play with their favourite toy, but were ignored by the experimenter. Other dogs played with another toy (not their favourite) with the experimenter. Still other dogs watched the human ‘playing’ with an object (a hole puncher they used to make holes in paper). The final group had an object in the room with them (a porcelain vase) which neither the experimenter nor the dog interacted with.

After 60 seconds in one these four conditions, the experimenter pretended to answer a phone call, and left the room. This isn’t because dogs are thought to understand phones, but rather to ensure that the dog continued to hear the experimenter’s voice when they left the room, so they were reminded of their presence.

Another experimenter then came into the room, picked up the object, and hid it in one of four possible cupboards. That experimenter then left the room, and the original one returned, with no idea where the object was hidden. They began to look for the object, in four distinct phases. Firstly, they sat on the spot where the object had been previously. They then ‘looked’ for the object whilst sitting in one place, raising their arms and saying ‘Hmm., that’s weird. It was there, and now it’s gone. I don’t understand it.’

Thirdly, the experimenter addressed the dog directly, asking where the item had gone. Finally, the experimenter stood up and looked around, but remained silent. After these four phases were complete (taking only 35 seconds in total) the experimenter had to guess the location of the object, using the behaviour of the dog (‘what’s that, Lassie? The vase is hidden in the cupboard on my left?’)

If the dog’s communication led the experimenter to the correct hiding place, she would exclaim, ‘wow! Here it is! Great!’ If, on the other hand, the item was not where the dog had signalled it might be, she would say, ‘oh, too bad! It’s not here.’ If she received no signals from the dog, she did not look for the object, but instead would just lift her arms and shoulders and say, ‘too bad, we can’t find it’.

Each dog received four sessions, each of these containing four trials (each of the trials in one of the four possible treatments with the four different objects).

So- did the dogs tell the humans where the objects were hidden? Well, sometimes. The interesting finding here is that what the dogs communicated depended on who the experimenter was. When the experimenter was a stranger, the dog would alert them to the location of the object only when it was something that they were interested in (the two different dog toys, but not for the hole punch or vase). However, when the experimenter was their owner, the dogs would alert them to the location of the object in all cases, even when it was of no interest to them.

Because it seemed that dogs might be trying to tell their owners things the owners didn’t know, the experimenters did a second follow-up experiment. This experiment was similar to the first, except this time the two objects were both ones that the dog had no interest in, but one of which was of great interest to the owner, and the other was not.

Both the objects were presented at the same time, and both were hidden, to see whether the dog would point out the relevant one to their owner. For example, the owner would pick up and use a pair of scissors, and then pick up a roll of sellotape but not use it. When she came back into the room she would be holding a piece of paper and ‘look’ for the object she needed following the same phases of ‘looking’ as in the previous experiment. They also had another condition where one of the two objects was the dog’s favourite toy, as a comparison to these two ‘human-interest’ objects.

It was found that the dogs did direct the humans to an object in most cases (e.g. scissors or sellotape) but not to the particular object they needed. However, when the object in question was the dog toy, they directed the person towards it overwhelmingly more often than to the other object.

So, was I right about Lassie? From the second experiment, it does seem that dogs do not differentiate between objects that an owner needs and ones they don’t need (which could lead Lassie leading little Tommy to a shovel rather than to a fire-extinguisher, although it seems most likely that he’d just lead him to a dog toy). On the other hand, the first experiment showed that dogs were more likely to lead humans to the object they wanted when the human in question was their owner rather than a stranger. However, this was even the case when the human had shown no interest in the object. So, it seems that dogs are not able to tell which object a human wants based on the person’s past behaviour, despite their ever endearing motivation to try.

 

Reference:

Kaminski, J., et al., (2011) Dogs, Canis familiaris, communicate with humans to request but not to inform, Animal Behaviour, doi:10.1016/j.anbehav.2011.06.015

Image credits:

Chicken/ Lassie cartoon: Doug Savage, www.savagechickens.com


Crows take a look in the mirror

One question in an animal cognition is whether animals other than humans have the ability to recognise themselves. A classic way of testing this, established in 1970 by Gordon Gallup, is the ‘mirror test’.

At first glance this might seem a rather straightforward test: get an animal to look in the mirror and see whether it seems to recognise itself, or responds as if it were looking at someone else. However, there are more factors to consider than are at first apparent. For example, whether the animal in question has ever experienced anything akin to mirrors before in its life will greatly impact on how it responds to a mirror. Humans which have been blind and then had sight restored to them, or children that have never encountered a mirror before do not recognise themselves when looking in one, and react as if they were seeing another person. However, before not too long people recognise that it is in fact themselves they are seeing.

Some of the ways chimpanzees react when looking in the mirror

Similarly, when chimpanzees first look in the mirror they react as if they were seeing another chimpanzee. However, they too then realise that it is in fact themselves they are seeing. Once they become familiar with the mirror they then use it to see parts of their body they have never seen before (yes, predictably the anal-genital area – and some people doubt that these are our closest living relatives). They also used the mirror for more respectable activities, like cleaning their eyes, nose, and teeth.

To test whether chimps really recognise themselves in the mirorr, researchers first llowed chimps to become accustomed to their appearance in a mirror. They then drew a coloured mark on to the forehead of the chimp in question. When the chimps were not provided with a mirror, they did not touch the coloured-in area on their heads. However, when they were given mirror, they did start touching this area, indicating that they were aware how mirrors work.

A video of the ‘mark test’ in humans and other primates (skip to half way through the video):

The ‘mark test’ has now been carried out in a variety of animals, and it seems that a number of animals also have mirror self-recognition: other great apes (bonobos, orang-utans and gorillas), bottle-nose dolphins, an Asian Elephant, and two Eurasian magpies. Animals that do not seem to be able to recognise themselves in a mirror include some monkey species, fish, gibbons, sea lions, dogs, cats and parrots.

A less scientific demonstration of a lack of mirror self-recognition in a cat:

Whether the fact that an animal can recognise itself in a mirror means that it has self-recognition akin to humans in something which has been long debated, and cannot be answered by the ‘mark test’. However, a number of animals which have not been able to recognise themselves, have nonetheless showed interesting and varied results when looking at other things in the mirror. Other mirror tasks apart from the ‘mark test’ include ones where animals have to use the mirror to find a hidden reward. In order to do this, they potentially need to understand how the object in the mirror is a reflection of an object in the real word.

In a recent study, scientists used this kind of task to see whether ten New Caledonian crows were able to use mirrors. First, crows were given a mirror which they were encouraged to interact with by leaving food (cubes of meat) next to it. They were exposed to the mirror for 10 minutes a day, for up to six days. The crows were able to walk behind the mirror to see if there was another individual there. At first, as the scientists predicted, when the crows first saw themselves in the mirror they reacted aggressively, as if to another individual. This aggressive behaviour did not decrease over the series of ten trials of which the crows were tested, and the crows did not show any behaviour indicating that they worked out that they were looking at themselves. However, this was a relatively short set of trials, and it could be that if they were given longer to experience mirrors they would have learned how they work.

After the initial aggressive response, the crow would then frequently examine the back of the mirror, and search behind the mirror, as if for the ‘other’ individual. This is also what children and non-human primates have been found to do. This exploration increased the more time they spent with the mirror.

Another type of crow, the hooded crow

Two crows who had this mirror experience, and two new crows who had not experienced mirrors were then tested on a task where they had to use a mirror to retrieve food. At the start of this task, birds were given a mirror placed on the floor, with meat off it (which they readily ate). A perch was then placed above the mirror (so that they could sit on the perch and look down into the mirror). The birds were then given meat to eat off the mirror and off of the perch, so they could get used to the set-up. The researchers then hung the meat underneath the perch on bits of string, and the birds learned to lean off the perch to retrieve the food hanging on the string, which hung above the mirror on the ground. Finally, two boxes were placed on top of the mirror, below the bird’s perch. The way that these boxes were built meant that they could be used to obstruct the crow’s view of the food. At first, the crow could see both the meat hanging below the perch, and its reflection in the mirror. However, over time the researchers altered the boxes so that the birds could no longer see the real meat, and instead could only see which box it was in if they used the reflection of the meat.

After training with this set-up, the birds were then tested with a set-up where they had four boxes, only one of which contained hidden food. They were given 30 trials to ‘solve the task’ (find the hidden food using only the reflection to guide them). Although it was not immediate, all four of the birds were able to learn to use the mirrors to find the hidden meat, becoming better at doing so as the trials went on. Unexpectedly, the birds which had not had previous experience with mirrors actually solved the task faster than the two which had.

So, does this study show that these crows understand mirrors? Well, probably not. Given the number of errors birds made in the final test before learning to find the food, it seems more likely that the birds learned a ‘rule’, such as ‘moving towards the mirror image of food and searching there leads to real food.’ However, this is not to say that with more experience the crows may come to learn how mirrors reflect objects in the real world.

Photo credits: crow by Marko_K, chimpanzee photo from Povinelli et al. (1993). 

References:

Medina, F. S., et al., (2011) New Caledonian crows’ responses to mirrors, Animal Behaviour, doi:10.1016/j.anbehav.2011.07.033

Pearce, J.M. (1997) Animal learning and cognition: An introduction. Psychology Pr.

Povinelli, D.J., Rulf, A.B., Landau, K.R. & Bierschwale, D.T. (1993) Self-recognition in chimpanzees Pan troglodytes: Distribution, ontogeny, and patterns of emergence. Journal of Comparative Psychology 107(4): 347.

Budgies remember the sound of their mates

What do shingleback lizards, budgerigars and Mexican grey wolves all have in common? All these animals are monogamous: they generally mate with a partner for a substantial period of time, in many cases to raise offspring together. An obviously important prerequisite to being monogamous is having the ability to recognise your partner, even if you don’t see them for a while.

In many birds, mates recognise each other by the their vocalisation (what their particular call sounds like). For example, colonial seabirds can remember what their partner sounds like even when not seeing them for months at a time.

When hearing the words ‘vocalisation’ and ‘bird’ the first thing that is likely to come to mind is the parrot, possibly Alex the Parrot. Parrots are unusual for birds in that they are able to learn to make new vocalisations throughout their lives, and not just when they are young.

A video of the famous African Grey parrot, Alex, demonstrating some vocal learning:

 

One particular parrot species, the budgerigar (or budgie), is monogamous. Both the male and the female have distinctive calls. When a male and female budgie are together (and love each other very much) they call to each other more often. This indicates that their calls are something to do with keeping pairs close and maintaining their bond. In the early days of courting, the male budgie will imitate the female’s call in order to impress her. The females do not do the same to the males, but prefer males that are particularly good at imitating their own calls (I think it might just freak me out if someone started doing this to me).  Once the male and the female have laid eggs, their calls start to become more different again. Therefore, when the next breeding season comes around, the females can’t rely on the males’ calls being the same as their own.

Budgerigar, Melopsittacus undulatus

In the lab, it is known that female and male budgies recognise each other after being separated for 70 days. However, it is not known how much of this recognition is based on what the other bird looks like, and how much is based on what they sound like. A recent study looked to see whether females remember the males they have paired with based on what they sound like. To do this, the researchers paired male and female budgies. They were then separated, and not allowed to see or hear one another. The female was then played the sound of her mate’s call and of another male’s call, to see if she would prefer the sound of her mate’s call (measured by how much she called back to it), and thus demonstrate whether she had some memory of it.

As females tend to prefer calls that are similar to their own, and as the males’ call becomes more similar to hers as time went on, the scientists needed to control for this. They did so in three ways: firstly, they paired males and females together at random, so that females were not selecting males with calls more similar to themselves to mate with. Secondly, they recorded males’ calls before they had paired with the females and started to make their own calls more similar to hers. And thirdly, when the researchers were playing back the two calls to the female they made sure that they were equally dissimilar to her call.

The researchers tested the female’s response to her mate’s call and the other male’s call at four different times after being separated (zero, one, two and six months). They found that the female preferred her mate’s call after one month, showing that she did remember what he sounded like after this period of time. However, she did not respond to his call after a longer period of time. A possible reason for this result is that the female has forgotten what her mate sounds like. However, previous work has shown that budgie females are actually very good at remembering calls (for up to 180 days). So, it could be that the female is not forgetting what her mate sounds like but rather she just doesn’t like him any more after this time. Why the females might lose interest after this time is another study waiting to be done…

 

photo credit: Elektrofisch

Reference: Eda-Fujiwara, H., Kanesada, A., Okamoto, Y., Satoh, R., Watanabe, A. & Miyamoto, T. (2011) Long-term maintenance and eventual extinction of preference for a mate’s call in the female budgerigar. Animal Behaviour. doi:10.1016/j.anbehav.2011.07.030