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Ghirlanda et al. (2017) reviewed sequence discrimination learning studies in various species and concluded that non-human animals have a limited ability to discriminate between stimulus sequences. In these studies, animals had to learn which of several presented sequences (e.g., auditory sequences consisting of bird song snippets or visual sequences consisting of light flashes or coloured squares appearing on a screen) were rewarded and which were not. The rewarded sequences were usually chosen by the experimenter, and there was nothing inherent in the rewarded sequences that suggested to the participant that these sequences yielded a reward, but not the other sequences. It could be possible that providing non-human animals with a physical causal cue indicating which sequence is the “correct” one could facilitate their sequence discrimination learning because 1) physical-causal relations between items in a sequence could draw an animal’s attention to the sequence information per se, and 2) help the animal learn which sequence is being followed by a reward. In this study, we investigate this hypothesis in capuchin monkeys.

Here we store the datasets and analysis scripts associated with the "Shifting Shelf manuscript" (accepted)

Ghirlanda et al. (2017) reviewed sequence discrimination learning studies in various species and concluded that non-human animals have a limited ability to discriminate between sequences (see also Enquist et al., 2023). In these studies, animals had to learn which of several presented sequences (e.g., auditory sequences consisting of bird song snippets or visual sequences consisting of light flashes or coloured squares appearing on a screen) were rewarded and which were not. The rewarded sequences were usually chosen by the experimenter, and there was nothing inherent in the rewarded sequences that suggested to the participant that these sequences yielded a reward, but not the other sequences. It could be possible that providing animals with a physical causal cue indicating which sequence is the “correct” one could facilitate their sequence discrimination learning because 1) physical-causal relations between items in a sequence could draw an animal’s attention to the sequence information per se, and 2) help the animal learn which sequence is being followed by a reward. In this study, we investigate this hypothesis in chimpanzees. References: Enquist, M., Ghirlanda, S., & Lind, J. (2023). The Human Evolutionary Transition: From Animal Intelligence to Culture. Princeton University Press. Ghirlanda, S., Lind, J., & Enquist, M. (2017). Memory for stimulus sequences: a divide between humans and other animals?. Royal Society open science, 4(6), 161011.

Ghirlanda et al. (2017) reviewed sequence discrimination learning studies in various species and concluded that non-human animals have a limited ability to actively discriminate between “arbitrarily” composed stimulus sequences. However, whether the same conclusion holds for a context in which less arbitrary, i.e., causally logical, sequences are used still needs to be determined. We will compare sequence discrimination learning in various primate species between two conditions: a “causal cue” condition in which there is a salient physical causal cue indicating that a sequence (and which one) is being rewarded, and a “no causal cue” condition in which there is no such cue. This preregistration refers to a study with human adults only. Research with other groups/species have been or will be preregistered separately within this project.

In response to a new task in the comparative literature, which requires subjects to anticipate and prepare for a reward that has an equal probability of emerging from two exit points in a fork tube, the assertion has been made that nonhuman animals are unable to account for two mutually exclusive possibilities. However, there are physical limitations to this task design that advantage humans, who are more adapted to tasks requiring bimanual coordination. We propose an approach that analyzes search patterns instead, in order to assess the response of capuchin monkeys when faced with two mutually exclusive alternatives.

* Correspondence should be addressed to Manuel Bohn (manyprimates@gmai l.com). Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of short-term memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities. Publisher PDF

Executive functioning lies at the heart of any cognitive processing and plays a crucial role for cognitive development throughout childhood and beyond (Cowan, 2016). Two core executive functions are the abilities to update and manipulate information in mind. Updating describes the capacity to revise information in light of new input and to replace old with new information (Garon, Bryson, & Smith, 2008; van der Sluis, de Jong, & van der Leij, 2007). Manipulation refers to the ability to re-order items in mind, to relate them, and to integrate new pieces of information with existing knowledge (Diamond, 2013; Garon et al., 2008). Due to the fundamental role executive functions play for the development of reasoning, problem-solving, reading and writing and its predictiveness of academic success (Best, Miller, & Naglieri, 2011; Blair & Razza, 2007; Bull, Espy, & Senn, 2004; Bull, Espy, & Wiebe, 2008; Diamond, 2013, 2016; Garon et al., 2008; Hughes, 2011; St Clair-Thompson & Gathercole, 2006), researchers have been trying to get a better understanding of their development in early childhood. One hurdle in this endeavor has been the shortage of tasks suitable for use with young preschoolers, whose verbal abilities are often not yet advanced enough to be able to be administered versions of manipulation tasks that have been used with adults (e.g., backward word or digit span tasks). However, it cannot be ruled out that many of these tasks can be solved, or at least greatly facilitated, by visual tracking and updating instead of strictly requiring mental manipulation (Reindl et al., under review). In addition, research on mental rotation skills in young children suggests that the ability to manipulate representations in mind might have a more protracted development than many studies suggest (Estes, 1998; Noda, 2010). We recently designed a task (Rotating Grid Task, RGT) to assess updating and manipulation of working memory contents in children (Reindl et al., under review). The study showed that children aged 3 to 7 years found it difficult to truly manipulate mental representations if they had no concrete observable stimuli available to guide their understanding. In the current study, we aim to administer the task to a larger sample and a wider age range in order to investigate the developmental trajectory of the task. In addition, we add a few extra trials to help disambiguate some competing hypotheses (see below). We also will administer the backward Corsi span task, in order to relate children’s performance on the RGT with their performance on another, established manipulation task. Lastly, parents will fill in a short questionnaire (the Childhood Executive Functioning Inventory (CHEXI): https://chexi.se/) which assesses working memory and inhibitory control in children aged 4-12, in order to investigate a potential correlation between children’s performance in the task and their more everyday behaviour. Due to the Covid-19 pandemic, the study will be carried out in an online format.

Children make many mistakes while they learn, and it has been suggested that allowing them to correct their own mistakes may promote the ability to shift between superficial, rule-based procedures and more abstract, flexible reasoning (Karmiloff-Smith, 1992). However, a previous study exploring this with a causal trap-task (Yuniarto, Seed, & Gómez, unpublished) found mixed results, allowed some self-correction even in the control condition, and did not control for the amount of experience gained. Our current study adapts the trap-task to a novel digital format, using an online game to test 2.5- and 3-year-old children’s ability to reason about the causal roles of objects. In the practice phase, some children will be able to correct their mistakes (Self-Correction), whereas others will not (No-Correction Classic). A third group will also be prevented from self-correcting, but can practice the task until they have succeeded as often as the Self-Correction group (No-Correction Remedial). All children will then be tested on a transfer task. This study will investigate 1) whether self-correction improves children’s ability to learn a 2D trap-task; 2) whether initial practice with self-correction improves children’s ability to transfer knowledge to a harder version of the task; 3) whether self-correction confers a unique advantage in triggering conceptual change over equivalent, non-corrective experience; 4) whether these effects vary with age; and 5) whether there is a relationship between implicit (gaze direction) and explicit (behavioural performance, verbal report) measures of learning on this task.

A manual rotating grid task (RGT) with capuchin monkeys designed to test the extent to monkeys update and manipulate contents in working memory.

A crucial component of Executive Functions is the ability to switch attention between rules or mental “sets”, allowing quick and flexible adaption to new demands, problems or instructions (Brown & Tait, 2015b, 2015a; Cragg & Chevalier, 2012; Garon, Bryson, & Smith, 2008; Ionescu, 2012). Over the last decades, research on the development of attentional set shifting has gained much attention due to the critical role Executive Functions play for regulating other cognitive abilities and their predictiveness of school readiness, academic, professional and relationship success, and health behaviours (Best, Miller, & Naglieri, 2011; Blair & Razza, 2007; Bull, Espy, & Senn, 2004; Bull, Espy, & Wiebe, 2008; Diamond, 2013, 2016; St Clair-Thompson & Gathercole, 2006). Yet, our understanding of the development of attentional set shifting in the preschool years is still somewhat patchy as the causes of the developmental increase in attentional shifting performance in the preschool years are still being debated (Cragg & Chevalier, 2012). Reindl et al. (in prep.) have recently created a novel attentional set shifting task for young children, based on the Intra-/Extradimensional (ID/ED) paradigm. In their proof of concept study, they showed that their “Shifting Tray” task was suitable for use with children as young as 3 years of age. In the current study, their task was adapted (here “Shifting Garden” task) to investigate whether an online task can capture the attention set shifting abilities of pre-schoolers similarly to an in-person study. In contrast to the original study, which used a total change paradigm, the stimuli in the current study will stay the same between the pre- and post-switch phases (no change paradigm) in order to avoid ceiling effects. It will be carried out in an online platform: first due to restrictions given the current Covid-19 pandemic, and also because moving the test online will reduce costs in administering the study and can extend the geographical reach of the study. Children between 3 and 5 years of age will be tested. They will be randomly assigned to one of two conditions (ID, ED). In the ID shift, the relevant dimension in the pre-switch phase will stay the same for the post-switch phase and in the ED shift, the relevant dimension in the pre-switch phase will be the irrelevant dimension in the post-switch phase.

One parallel between human and nonhuman working memory is that working memory maintenance is facilitated by stimulus familiarity. In humans, the prefrontal cortex is more active when subjects remember familiar images compared to novel images, working memory capacity is greater for familiar stimuli that exist as long-term representations, and familiar representations consume fewer working memory resources than unfamiliar representations. Language grants human working memory an advantage in maintaining unfamiliar stimuli in mind through the ability to transform unfamiliar stimuli into familiar stimuli via verbal recoding. For instance, when a participant is presented with a completely novel image to hold in mind, they can recode the unfamiliar image into familiar words (e.g., red house, green field) and then rehearse the results of recoding. The value of such recoding is evident experimentally when human participants struggle to remember complex geometrical figures or fractals that are difficult to recode, or when memory suffers under articulatory suppression. Recently I have begun a line of research providing evidence that rhesus monkeys do show evidence of working memory rehearsal with novel stimuli, but to a much lesser degree than familiar stimuli, and the supervisor has provided evidence that chimpanzees engage in working memory maintenance for multiple items at once. These two lines of work will be combined to investigate the extent to which children compare to monkeys and human children in the ability to maintain novel versus familiar images in working memory. It is possible that language may allow working memory to have access to a much wider range of stimuli to maintain, and a method of rehearsal that is much more robust. This series of studies will investigate the extent to which children aged 3-7 rely on working memory to remember familiar versus novel stimuli.

Ghirlanda et al. (2017) reviewed sequence discrimination learning studies in various species and concluded that non-human animals have a limited ability to actively discriminate between arbitrary stimulus sequences. However, whether the same conclusion holds for a context in which less arbitrary, i.e., causally logical, sequences are used still needs to be determined. Therefore, we will compare sequence discrimination learning in various primate species between two conditions: a causal condition in which there is a causal cue indicating that a sequence (and which one) is being rewarded, and an arbitrary condition in which there is no such cue. This preregistration refers to an initial study with squirrel monkeys only. Research with other species will be preregistered separately.

Contains preregistrations and data

Additional materials; Raw data and analyses