new research has that the jay

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Just like humans, more intelligent jays have greater self-control

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A study has found that Eurasian jays can pass a version of the ‘marshmallow test’ – and those with the greatest self-control also score the highest on intelligence tests.

It’s just mind-boggling that some jays can wait so long for their favourite food." Alex Schnell

This is the first evidence of a link between self-control and intelligence in birds.

Self-control - the ability to resist temptation in favour of a better but delayed reward – is a vital skill that underpins effective decision-making and future planning.

Jays are members of the corvid family, often nicknamed the ‘feathered apes’ because they rival non-human primates in their cognitive abilities. Corvids hide, or ‘cache’, their food to save it for later. In other words, they need to delay immediate gratification to plan for future meals. The researchers think this may have driven the evolution of self-control in these birds.

Self-control has been previously shown to be linked to intelligence in humans, chimpanzees and – in an earlier study by these researchers – in cuttlefish. The greater the intelligence, the greater the self-control.

The new results show that the link between intelligence and self-control exists across distantly related animal groups, suggesting it has evolved independently several times.

Of all the corvids, jays in particular are vulnerable to having their caches stolen by other birds. Self-control also enables them to wait for the right moment to hide their food without being seen or heard.

The results are published today in the journal Philosophical Transactions of the Royal Society B .

To test the self-control of ten Eurasian jays, Garrulus glandarius , researchers designed an experiment inspired by the 1972 Stanford Marshmallow test - in which children were offered a choice between one marshmallow immediately, or two if they waited for a period of time.

Instead of marshmallows, the jays were presented with mealworms, bread and cheese. Mealworms are a common favourite; bread and cheese come second but individuals vary in their preference for one over the other.

The birds had to choose between bread or cheese - available immediately, and mealworm that they could see but could only get to after a delay, when a Perspex screen was raised. Could they delay immediate gratification and wait for their favourite food?

A range of delay times was tested, from five seconds to five and a half minutes, before the mealworm was made available if the bird had resisted the temptation to eat the bread or cheese.

All the birds in the experiment managed to wait for the worm, but some could wait much longer than others. Top of the class was ‘JayLo’, who ignored a piece of cheese and waited five and a half minutes for a mealworm. The worst performers, ‘Dolci’ and ‘Homer’, could only wait a maximum of 20 seconds.

“It’s just mind-boggling that some jays can wait so long for their favourite food. In multiple trials, I sat there watching JayLo ignore a piece of cheese for over five minutes – I was getting bored, but she was just patiently waiting for the worm,” said Dr Alex Schnell at the University’s Department of Psychology, first author of the report.

The jays looked away from the bread or cheese when it was presented to them, as if to distract themselves from temptation. Similar behaviour has been seen in chimpanzees and children.

JayLo patiently ignores the cheese (in right box) to wait for the worm (in left box).

The researchers also presented the jays with five cognitive tasks that are commonly used to measure general intelligence. The birds that performed better in these tasks also managed to wait longer for the mealworm reward. This suggests that self-control is linked with intelligence in jays.

“The birds’ performance varied across individuals – some did really well in all the tasks and others were mediocre. What was most interesting was that if a bird was good at one of the tasks, it was good at all of them – which suggests that a general intelligence factor underlies their performance,” said Schnell.

The jays also adjusted their self-control behaviour according to the circumstances: in another experiment where the worm was visible but always out of reach, the jays always ate the immediately available bread or cheese. And the length of time they were willing to wait for the worm fell if it was pitted against their second most preferred food as the immediate treat, compared to their third. This flexibility shows that jays only delay gratification when it is warranted.

Research by other scientists has found that children taking the Stanford marshmallow test vary greatly in their self-control, and this ability is linked to their general intelligence. Children that can resist temptation for longer also get higher scores in a range of academic tasks.

This research was approved by the University of Cambridge Animal Ethics Review Committee, and performed in accordance with the Home Office Regulations and the ASAB Guidelines for the Treatment of Animals in Behavioural Research and Teaching.

The research was funded by the Royal Society, Fyssen Foundation, and European Research Council.

Schnell, AK, Boeckle, M, Clayton, NS. ‘ Waiting for a better possibility: delay of gratification in corvids and its relationship to other cognitive capacities .’ Philosophical Transactions of the Royal Society B, October 2022.

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Hiding behavior of the scrub jay: More stress than smarts?

The fact that scrub jays continually move their food from one hiding place to another (known as recaching) does not necessarily imply subtle social intelligence on their part -- it could simply be due to stress. PhD student Elske van der Vaart discovered this, together with her supervisors Charlotte Hemelrijk and Rineke Verbrugge, with the aid of a computer model.

Their study was published on 1 March 2012 in the scientific journal PLoS ONE . Science journalist Michael Balter also writes about their research in the 1 March 2012 issue of Science.

Nearly all birds belonging to the corvid or crow family hide food underground, storing it for later. However, when fellow corvids see something being buried, they enjoy stealing it. The Western scrub jay (Aphelocoma californica), a blue-grey jay home to the southern USA, is well known for its smart little tricks to avoid being robbed.

Social intelligence

The scrub jay trick is as follows: if it notices other birds watching, it buries its worms as far away as possible and keeps recaching, over and over again, as if attempting to confuse the spies. As soon as it is on its own, it recaches its worms one more time. This behaviour appears so smart that speculation has it that the scrub jays are able to put themselves in another scrub jay's position, and that they are able to come up with a line of reasoning on what others see and know, for instance: 'If my fellow scrub jay knows where I've hidden the worm, I need to hide it again, somewhere else.' This would be very special, as this is an ability only attributed to humans and perhaps some monkeys.

Van der Vaart and her supervisors, however, have developed an alternative theory which explains the birds' behaviour without making much reference to social behaviour: a scrub jay may know from experience that its worms are safest if they are hidden far away from any other birds. If other birds are watching while a scrub jay hides its food and if it then keeps recaching it, this may very well not be due to the fact that it is trying to mislead the other birds, but because it is becoming stressed by their presence. It may perhaps be thinking: 'I need to hide more worms for later!' When at last the scrub jay is on its own again, it turns out that the jay itself is the one really confused by all the moving: many worms are no longer where the jay expects them to be. The result is that the bird becomes even more stressed and continues to move worms.

Virtual bird

Van der Vaart developed this theory using a corvid computer model that she had designed earlier to study corvid memory and learning behaviour. In essence, she created a 'virtual bird'. The PLoS ONE article describes how in experiments this virtual bird displays the same recaching behaviour as a real jay, and of course without any extensive insight into what other jays are thinking. Science reports that empirical researchers are planning to test the predictions made by the computer model. This should ultimately lead to true understanding of the so often admired scrub jay intelligence.

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Story Source:

Materials provided by University of Groningen . Note: Content may be edited for style and length.

Journal References :

• Elske van der Vaart, Rineke Verbrugge, Charlotte K. Hemelrijk. Corvid Re-Caching without ‘Theory of Mind’: A Model . PLoS ONE , 2012; 7 (3): e32904 DOI: 10.1371/journal.pone.0032904
• M. Balter. 'Killjoys' Challenge Claims of Clever Animals . Science , 2012; 335 (6072): 1036 DOI: 10.1126/science.335.6072.1036

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Strange & offbeat.

Little evidence that Eurasian jays protect their caches by responding to cues about a conspecific's desire and visual perspective

Affiliations.

• 1 Department of Psychology, University of Cambridge, Cambridge, United Kingdom.
• 2 Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy.
• 3 Institute for Globally Distributed Open Research and Education (IGDORE), Sweden, Sweden.
• 4 Department of Psychological & Brain Sciences, Johns Hopkins University, Baltimore, United States.
• 5 Department of Psychology, Durham University, Durham, United Kingdom.
• 6 Department of Psychology, Faculty of Humanities and Social Sciences, University of Rijeka, Rijeka, Croatia.
• PMID: 34505575
• PMCID: PMC8536255
• DOI: 10.7554/eLife.69647

Eurasian jays have been reported to protect their caches by responding to cues about either the visual perspective or current desire of an observing conspecific, similarly to other corvids. Here, we used established paradigms to test whether these birds can - like humans - integrate multiple cues about different mental states and perform an optimal response accordingly. Across five experiments, which also include replications of previous work, we found little evidence that our jays adjusted their caching behaviour in line with the visual perspective and current desire of another agent, neither by integrating these social cues nor by responding to only one type of cue independently. These results raise questions about the reliability of the previously reported effects and highlight several key issues affecting reliability in comparative cognition research.

Keywords: Eurasian jay; corvids; desires; ecology; perspective; replication; theory of mind.

Plain language summary

Eurasian jays, Garrulus glandarius , are members of the crow family. These large-brained birds hide food when it is abundant, and eat it later, when it is scarce. Previous studies have found that jays avoid theft by other jays by carefully deciding what food to hide, and where. In one study, they preferred to hide their food behind an opaque barrier, rather than a transparent one, when another jay was watching. In a second study, they preferred to hide food that the watching jay had already eaten enough of, and thus did not want. These studies suggest that jays have flexible cognitive skills when it comes to protecting their food. They respond to whether a potential thief can see their hiding place and to how much a thief might want the food they are stashing. The next question is, can Eurasian jays combine these two pieces of information? For example, if a jay has two types of food they could hide when another jay is present, but only has one place to hide them (either in view or out-of-view of the other jay), does the first jay prefer to stash the food that the second jay has already eaten, and therefore does not want anymore, only when the hiding place is visible to second jay? To find out, Amodio et al. watched Eurasian jays hiding macadamia nuts or peanuts in the presence of another jay. In the first setup, jays were given one food to hide and two possible hiding places, one opaque and one transparent, while being watched by a jay that had either had its fill of the food, or not tried it. In the second setup, jays were given both foods to hide, but only had one place to hide them (either transparent or opaque); while being watched by a jay that had eaten enough of one of the foods. Contrary to expectations, the jays did not seem to be able to combine the information about what the other jay could see and what it had been eating. In fact, they seemed unable to respond to either piece of information. When Amodio et al. repeated the original experiments, the jays did not seem to prefer to hide food out of sight, or to hide food that the watcher had already eaten. These results raise questions about the repeatability of experiments on food hiding strategies in birds of the crow family. It suggests that previous findings should be further investigated, potentially to identify important factors that might affect the repeatability of food-hiding tactics. Repeating the experiments may show how best to investigate behavioural patterns in jays in the future.

© 2021, Amodio et al.

Publication types

• Research Support, Non-U.S. Gov't
• Feeding Behavior*
• Passeriformes / physiology*
• Social Behavior*

Grants and funding

• BB/M011194/1/BB_/Biotechnology and Biological Sciences Research Council/United Kingdom