“Cup Game” Provides Insight into Monkeys’ Understanding of Hidden Objects

Written by: Dr. Blake Morton

Some of you may have seen or heard about our capuchin and squirrel monkeys participating in a special type of problem-solving task, which we’ve affectionately dubbed “the cup game”. This task is designed to measure object permanence, which is a fancy term psychologists’ use to describe why an individual knows that when an object or person goes out of sight, that object/person still exists (i.e. it hasn’t fallen off the face of the earth!). In humans, this mental ability has fully developed by around two years of age, which is why children younger than this typically find the “peek-a-boo!” game hilarious: when you cover your face with your hands, children who have not yet developed object permanence think you’ve disappeared, which is why they act surprised as you “magically” reappear and say “peek-a-boo!” with a grin. It’s a classic stage in child cognitive development.

We’ve known for quite some time that monkeys and other animals like dogs and birds have this ability too. Not surprisingly, this ability should exist in many different kinds of animals where, for example, individuals foraging in trees might benefit from understanding that hidden food items are behind branches and leaves, or that predators concealed by tall grass are still lurking nearby!

We use the cup game at Living Links to train new researchers who come to work with our monkeys. The task is fun and easy to administer, and it gives the monkeys and new researchers an opportunity to get to know one another! Have a look at one of our squirrel and capuchin monkeys participating in the cup game below.

Squirrel Monkeys Cup Game Video

Capuchin Monkeys Cup Game Video

As you can see in the videos, monkeys must choose between two different cups. One cup has a hidden food reward underneath it, the other cup does not. Each monkey gets the chance to play the game twice a day, once in the morning and then again in the afternoon. Within each of these sessions, monkeys can get up to ten food rewards if they choose the correct cup every time. The monkeys’ behaviour suggests that they possess object permanence because they always reach for the cup containing the hidden food reward, even when the position of each cup has been switched. A simple task, but it is clear that object permanence exists in these species – just like us!

 

Do Capuchin’s deceive their con-specifics with false alarm calls?

Written by: Kirsty-Marie Moran

Have you ever involuntarily screamed at a scary movie? Ever wondered why you couldn’t control it? Well, the underlying cause of this spontaneous vocalisation that draws all attention to you in that split second is emotion. This lack of control over some of our emotions is not unique to humans, we also share this with other species such as nonhuman primates. Primates may not scream at a scary movie when scared or startled but they do produce an alarm call when a threat is near by, communicating this message to their group mates. 

However, emotions do not always result in involuntary vocalisations, they can somewhat be controlled and used to your advantage, for instance, as a child if you cry because you did not get what you wanted and your parents give in then you learn to use those ‘crocodile tears’ to get what you want. This deceiving behaviour is something that primates such as chimpanzees also do in certain contexts

When competing for food, chimpanzees can produce a false alarm call, tricking others into thinking a threat is nearby which gives the calling chimpanzee an opening to go get food first. Up until recently, this deceptive behaviour has been limited to species with high cognitive abilities. However, recent evidence suggesting high cognitive abilities are not necessary for this deceptive behaviour has led to the belief that maybe smaller primates, such as brown tufted capuchins can also deceive their fellows, much like chimpanzees do.

This led to an important research question, ‘can Capuchins use alarm calls to deceive conspecifics or are these calls a product of involuntary emotion?’

One of our researchers at Living Links alongside researchers from German, Italian, and UK universities set out to answer this question by focusing on the occurrence of anxious behaviours i.e. scratching when these false alarm calls were produced by capuchins.

The researchers placed banana pieces on wooden platforms (figure 1) to stimulate food competition and elicit the ‘deceptive’ calls in wild black Capuchins at Iguazu National Park, Argentina. It was predicted that if anxiety drove the false alarm calls, then anxious behaviours and ‘deceptive’ alarm calls would happen together. Additionally, brown tufted capuchins at the Institute of Cognitive Sciences and Technologies in Italy were observed to check if their alarm calls and anxiety more generally occurred at the same time.

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Figure 1.

During the platform experiments in the wild, it was found that those who gave alarm calls displayed a lower level of anxiety. Whilst those who gave alarm calls in captivity displayed higher levels of anxiety. These findings suggest that anxiety was a reliable indicator of predator alarm calls, but that anxiety alone does not fully explain this phenomenon.

Overall, it was concluded that anxiety is necessary for the call to be produced, but some form of intentional control ultimately decided whether they would call or not. This suggests that it is unlikely these monkeys intentionally trick their group mates, but that they are driven by emotion and possibly associative learning.

 

 

Kean, D., Tiddi, B., Fahy, M., Heistermann, M., Schino, G., & Wheeler, B. C. (2017). Feeling anxious? The mechanisms of vocal deception in tufted capuchin monkeys. Animal Behaviour, 130, 37-46. doi:10.1016/j.anbehav.2017.06.008

Understanding primate feelings through their personalities – a keeper insight.


Written by: Kirsty-Marie Moran

Personalities come in all shapes and forms, contributing to what makes you different from another person. It is also an intriguing aspect of ourselves that we share with our primate cousins. We can ask each other if we are well but with animals, this is not so easy. It is each individual primate personality that could be the key to understanding how primates feel and because we are unable to ask how they feel, we can only observe and record what we see. 

There are several ways in which researchers have attempted to answer questions on how primates feel such as taking blood samples, measuring hormones, or sitting observing behaviours.

However, in a recent study at the National Institutes of Health, Georgia State University, the researchers asked for the help of the keepers – after all, many of them have spent years with these animals. Who would know the personalities of the primates better?

Positive allo-grooming. Known to strength the relationship between the giver and receiver.

Positive behaviours. These brown capuchins are engaging in some allogrooming.

Using a questionnaire based on studies of people’s happiness it has been possible to assess happiness in nonhuman primates. With many studies suggesting the results are similar to that of humans. In humans, happiness and welfare are directly linked and the study at Living Links attempted to assess welfare and subjective well-being (SWB) in brown capuchins. In doing this they aimed to determine if happiness and welfare are directly relatable in capuchins.

It was found (between 10 keepers and over 200 ratings completed), that there was a high agreement on the capuchins welfare. Finding no difference between SWB and welfare ratings, which suggests that like humans SWB and welfare are linked. Also, any low ratings of SWB and welfare ratings were found to be associated with the display of stereotypic behaviours (i.e. self-grooming), indicated that a questionnaire which took on average 3minutes could be a quick and reliable form of studying welfare.

This may change the way welfare is studied in the future. With findings such as these, it may be worthwhile incorporating SWB and welfare related questionnaires into any welfare related research in the future. Especially when you are lucky to have keepers who have spent considerably longer with these animals than the researcher (in most cases) has.

 

Reference:

Robinson, L. M., Waran, N. K., Leach, M. C., Morton, F. B., Paukner, A., Lonsdorf, E., Weiss, A. (2016). Happiness is positive welfare in brown capuchins (Sapajus apella). Applied Animal Behaviour Science, 181, 145-151. doi:10.1016/j.applanim.2016.05.029

The effect you as a ‘visitor’ have on squirrel monkeys.

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Written by Kirsty-Marie Moran and Zita Polgár

Ever wondered if the animals at the zoo notice your presence? And if they do, if they mind you peering in on them?

These are very important welfare questions with many zoos attempting to answer them, including our very own here at Living Links Research Centre situated within Edinburgh Zoo. A recently published paper in the American Journal of Primatology details the results of a study examining the ‘individual differences in zoo-housed squirrel monkeys’ reactions to visitors, research participation, and personality ratings’. The study tackles the important question on whether monkeys with different personalities react differently to visitors, as well as how the size of the visiting groups influences their responses. Understanding individual differences is important because it can improve the animals welfare by catering to each individual’s needs.

During the study, the researchers recorded how long the monkeys spent by the observation window when there were small groups of visitors, large groups or no visitors. They found that the monkeys spent more time up at the window when there were large groups of visitors than when there were small groups or no visitors at the observation window. Specifically, the researchers found personality differences between the monkeys. Those who scored higher on playfulness and scored lower on cautiousness, depression and solitude were more likely to be at the window when there were visitors there.

These results suggest that zoo visitors do not have a negative impact on the squirrel monkeys but rather have a positive impact. Zoo visitors appear to be a form of enrichment, especially in those monkeys with social personalities.

The researchers speculate that the squirrel monkeys at the centre have developed this response due to a number of factors, namely that they are provided with a variety of enrichment opportunities. They frequently have positive interactions with a variety of humans through voluntary research studies and they have the option to choose from five different enclosure areas with different levels of exposure to zoo visitors.

 

Reference

Polgár, Z., Wood, L., & Haskell, M. J. (2016). Individual differences in zoo-housed squirrel monkeys’ (Saimiri sciureus) reactions to visitors, research participation, and personality ratings. American Journal of Primatology. doi:10.1002/ajp.22639

 

Living Links changing the way animal social cognition is measured. Are photograph measures reliable?

Kirsty & BlakeWritten by Kirsty-Marie Moran & Blake Morton with thanks to Alaina Macri and Christoph Voelter.

 

 

I think we could all agree that seeing a photo of a person or place is different to seeing that person or place in real life…right? We react differently to photographs. For instance, if there was a picture of your boss, this wouldn’t stop you checking your private emails, would it? But if this person was there, it might. So, recording the behavioural responses to a photograph in humans, couldn’t possibly be representative of how humans would react to the real-life scenario.

However, this is exactly what is happening when measuring responses to photographs in primates. Scientists often use photos to test how animals perceive the world around them. For example, to test whether a dog can tell the difference between a happy versus sad person, they might record whether the dog whimpers more when it sees an image of a person crying versus laughing. Scientists can use photos instead of real-life stimuli to study animal behaviour because they’re cheaper and easier to bring into the lab. But in the absence of depth, smell, and movement, most animals can likely tell the difference between a photo versus the real thing. Behavioural responses to photos are interpreted to reflect how the primate would react in the real-life situation. Thus, recording how animals react to photos may not necessarily tell us how they would behave towards the same scenario in real life. Surprisingly, very few scientists take this problem into consideration when interpreting animals’ responses to photos.

In a recent collaborative study between Living Links and the Language Research Center of Georgia State University, Morton et al. (2016) investigated for the first time whether brown capuchin monkeys react to photos of the alpha male of their group (see below) in the same way as they do in real life.

LL morton experiment picture

Typically, lower-ranking capuchins react to the presence of an alpha male by either avoiding them or acting submissively in their presence (e.g. letting the alpha have first dibs on food). By placing food in front of a photo of the alpha male and then doing the same but in front of the real-life alpha, the researchers were able to compare whether the monkeys’ behaviour towards the photo could predict what would happen in reality.

The researchers found that the capuchins did not react to the photo in the same way as they did to the real-life alpha. Thus, a picture of their “boss” (the alpha male) did not fool the monkeys, let alone prevent them from grabbing the food next to the photo.

This study provides scientists with an important cautionary note when using photos to study animal behaviour.

Morton, F. B., Brosnan, S. F., Prétôt, L., Buchanan-Smith, H. M., O’Sullivan, E., Stocker, M., Wilson, V. A. (2016). Using photographs to study animal social cognition and behaviour: Do capuchins’ responses to photos reflect reality? Behavioural Processes, 124, 38-46. doi:10.1016/j.beproc.2015.10.005