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In contrast, the study shows that humans learned to distinguish the short sequences nearly immediately. Credit: Neuroscience News

Sequential Memory Is A Unique Human Trait

Summary: New research unveils a probable unique human ability to recognize and remember sequential information. Despite being our closest relatives, bonobos struggle to learn the order of stimuli in the same manner as humans.

This discovery contributes to understanding the cognitive distinctions between humans and other animals, explaining why only humans possess certain cultural abilities like language and advanced planning. This sequential memory might be the foundational block behind many uniquely human behaviors and capabilities.

Key Facts:

  1. The study reveals that bonobos, our closest relatives, cannot effectively remember the order of visual stimuli as humans can.
  2. Previous research has hinted that the ability to recognize and recall sequential data is uniquely human, critical for language and advanced planning.
  3. The research adds weight to the sequence memory-hypothesis, which postulates the evolution of this ability during human prehistory.

Source: Stockholm University

Remembering the order of information is central for a person when participating in conversations, planning everyday life, or undergoing an education. A new study, published in the scientific journal PLoS One, shows that this ability is probably human unique. Even the closest relatives of humans, such as bonobos, do not learn order in the same way.

“The study contributes another piece of the puzzle to the question of how the mental abilities of humans and other animals differ, and why only humans speak languages, plan space travel, and have learned to exploit the earth so efficiently that we now pose a serious threat to countless other life forms”, says Johan Lind, associate professor in ethology and deputy director at the Center for Cultural Evolution, Stockholm University. Since September also associate professor of ethology at Linköping University.

Already earlier research at Stockholm University has suggested that only humans have the ability to recognize and remember so-called sequential information, and that this ability is a fundamental building block underlying unique human cultural abilities.

But previously, this sequence memory-hypothesis has not been tested in humans’ closest relatives, the great apes. The new experiments now show that also bonobos, one of the great apes, struggle to learn the order of stimuli.

In the recently published book The Human Evolutionary Transition: From Animal Intelligence to Culture (Princeton University Press), ethologists Magnus Enquist and Johan Lind at Stockholm University, and Stefano Ghirlanda, researcher in psychology at Brooklyn College, New York, have launched a new theory for how humans became cultural beings. A central idea concerns the difference in how humans and other animals recognize and remember sequential information.

“We have previously analyzed a large number of studies that suggest that only humans recognize and remember sequential information faithfully. But, even though we analyzed data from a number of mammals and birds, including monkeys, there has been a lack of information from our closest relatives, the other great apes”, says Johan Lind.

In a series of experiments, memory abilities of bonobos and humans were tested by having them press computer screens to, among other things, learn to distinguish between short sequences, including pressing right if a yellow square comes before a blue square, or by pressing to the left of the blue square appears before the yellow square.

“The study shows that bonobos forget that they have seen a blue square already five to 10 seconds after it has disappeared from the screen, and that they have great difficulty learning to distinguish the sequences blue-square-before-yellow-square from yellow-square- before-blue-square, even though they have been trained for thousands of trials”, says Vera Vinken, associated with Stockholm University, now a PhD student in Great Britain at the Biosciences Institute, Newcastle University.

In contrast, the study shows that humans learned to distinguish the short sequences nearly immediately. However, it still remains to be shown exactly how our closest relatives can remember and use sequential information.

“We now know that our closest relatives do not share the same sequential mental abilities with humans. But even if the results indicate that their working memory works in principle in the same way as in rats and pigeons, no one has yet demonstrated this in practice”, says Magnus Enquist, professor emeritus and one of the founders of the Center for Cultural Evolution.

The new results provide further support for the sequence memory-hypothesis, that during human prehistory an ability to remember and process sequences evolved, a necessary mechanism for many uniquely human phenomena such as language, planning ability and sequential thinking.

About this memory research news

Author: Gunilla Nordin
Source: Stockholm University
Contact: Gunilla Nordin – Stockholm University
Image: The image is credited to Neuroscience News

Original Research: Open access.
A test of memory for stimulus sequences in great apes” by Johan Lind et al. PLOS ONE


A test of memory for stimulus sequences in great apes

Identifying cognitive capacities underlying the human evolutionary transition is challenging, and many hypotheses exist for what makes humans capable of, for example, producing and understanding language, preparing meals, and having culture on a grand scale.

Instead of describing processes whereby information is processed, recent studies have suggested that there are key differences between humans and other animals in how information is recognized and remembered.

Such constraints may act as a bottleneck for subsequent information processing and behavior, proving important for understanding differences between humans and other animals.

We briefly discuss different sequential aspects of cognition and behavior and the importance of distinguishing between simultaneous and sequential input, and conclude that explicit tests on non-human great apes have been lacking.

Here, we test the memory for stimulus sequences-hypothesis by carrying out three tests on bonobos and one test on humans. Our results show that bonobos’ general working memory decays rapidly and that they fail to learn the difference between the order of two stimuli even after more than 2,000 trials, corroborating earlier findings in other animals.

However, as expected, humans solve the same sequence discrimination almost immediately. The explicit test on whether bonobos represent stimulus sequences as an unstructured collection of memory traces was not informative as no differences were found between responses to the different probe tests.

However, overall, this first empirical study of sequence discrimination on non-human great apes supports the idea that non-human animals, including the closest relatives to humans, lack a memory for stimulus sequences.

This may be an ability that sets humans apart from other animals and could be one reason behind the origin of human culture.

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  1. Human are different an other animal so we have use the system that we developed for our selves and our own brain like to work and it would be interesting

  2. Science has discovered that humans are uniquely different from other animals? Groundbreaking, lol!

  3. I understand the potential excitement that a single study can ignite. This study, however, and worse this news-article, ignores a vast assortment of decades old literature that has shown time and time again that sequence memory is, in fact, shared across a wide array of species. Here’s an appetizer sampler from birds, rodents, and… apes:

    Terrace HS, Mcgonigle B (1994) Memory and representation of serial order by children, monkeys, and pigeons. Curr Dir Psychol Sci

    Barone P, Joseph J-P (1989) Prefrontal cortex and spatial sequencing in macaque monkey. Exp Brain Res 78:43–54.

    Kermadi I, Jurquet Y, Arzi M, Joseph JP (1993) Neural activity in the caudate nucleus of monkeys during spatial sequencing. Exp Brain Res

    Funahashi S, Inoue M, Kubota K (1997) Delay-period activity in the primate prefrontal cortex encoding multiple spatial positions and their order of presentation. Behav Brain Res

    Ninokura Y, Mushiake H, Tanji J (2003) Representation of the temporal order of visual objects in the primate lateral prefrontal cortex. J Neurophysiol

    Inoue M, Mikami A (2006) Prefrontal activity during serial probe reproduction task: encoding, mnemonic, and retrieval processes. J Neurophysiol

    Allen, T. A., Salz, D. M., McKenzie, S., & Fortin, N. J. (2016). Nonspatial sequence coding in CA1 neurons. Journal of Neuroscience, 36(5), 1547-1563.

    Shahbaba, Babak, et al. Hippocampal ensembles represent sequential relationships among an extended sequence of nonspatial events. Nature communications 13.1 (2022): 787.

    However, apart from birds (I didn’t even tap into the _song_-bird literature), rodents, and primates (and thus likely most other species), most damning to the authors claim of a “uniquely human” cognitive capacity is evidence from some of the smallest brains. Yes, even insects (bee’s and *maybe* ants) have been suggested to exhibit signs of sequence memory:

    Collett, T. S., Fry, S. N., & Wehner, R. (1993). Sequence learning by honeybees. Journal of comparative Physiology A, 172, 693-706.

    Zhang, S., Mizutani, A., & Srinivasan, M. V. (2000). Maze navigation by honeybees: learning path regularity. Learning & Memory, 7(6), 363.

    Graham, P., & Mangan, M. (2015). Insect navigation: do ants live in the now?. The Journal of Experimental Biology, 218(6), 819-823.

    Could sequences be the basis of storytelling and by extension, a fundamental factor in driving human culture? Probably. But the title and prose, particularly from a null result in the face of overwhelming previous evidence, is in error to the point this news article should be likely be retracted in its current state…

  4. Bonobos way outperform humans on immediate photographic ordinal memory function, interestingly. They are shown a screen with the numbers 1 through 9 scattered across it,for less than seconds, and then goes blank and they are able to memorize in that time where all the numbers were and tap their locations *in ordinal sequence* on the now blank screen *extremely quickly and correctly*. NO HUMAN HAS BEEN ABLE TO EVEN COME CLOSE TO DOING THIS. Like, we need to look at screen for a significant amount of seconds in order to remember where even ONE of the nine numbers are, and we need many many seconds to be able to recall all 9 positions in ordinal sequence and even then we make alot of mistakes.
    (Its a Japanese study, there is video too).
    So although humans are unique and superiorly skilled in certain memory abilities; Bonobos are unique and superior to us in *other* specific memory abilities. We diverged with different memory specialities.
    One thinks the flash photographic ordinal memory would be good for quickly looking out over area and determining where all the troop members are,in order from the Alpha matriarch to the lowest ranking infant member.
    Whereas obviously sequential memory is going to be more useful for planning how to weave a basket or other technology, or to carry out a complex hunt involving traps.

  5. What about animals not so closely related to us? Just because bonobos share a lot with us doesn’t mean they have all our attributes. The smart birds should be tested also. Are humans born with this ability or is it developed later

  6. So we used systems that we developed for ourselves, the way our own brains like to work. Systems we have already learned and used our entire lives. Computers and tables, shapes, colors, and arrows that hold no meaning to the animal on their own. Then we view it as apples to apples for sequencing ability? Then we try to apply those learnings to the entire animal kingdom… There is plenty of evidence for animals using sequences in nature, for things that matter to them.
    You named birds. How about bird songs? Sequential. There are multiple birds that can talk. Which is again a long sequence of sounds and pauses that they hear then repeat in sequence. Crows can make tools out of parts that individually are useless. They can use them to solve complex problems that in some cases would stump some people. It’s hard to imagine doing that without thinking it through in a sequence. If you are looking for sequencing abilities try looking in the areas animals have strong abilities. Don’t use foreign unfamilar concepts like geometric shapes. How often do you come across 2d yellow squares in nature?
    If in fact some of our closest ancestors struggle with sequencing. But it exists in other places far away from us evolutionarily. That would show that sequencing is very much not a trait special to us but that it naturally arises on its own. Making it not at all a distinctly human trait.

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