String Pulling Research Articles

How to solve novel problems: the role of associative learning in problem-solving performance in wild great tits Parus major

Although problem-solving tasks are frequently used to assess innovative ability, the extent to which problem-solving performance reflects variation in cognitive skills has been rarely formally investigated. Using wild breeding great tits facing a new non-food motivated problem-solving task, we investigated the role of associative learning in finding the solution, compared to multiple other non-cognitive factors. We first examined the role of accuracy (the proportion of contacts made with the opening part of a string-pulling task), neophobia, exploration, activity, age, sex, body condition and participation time on the ability to solve the task. To highlight the effect of associative learning, we then compared accuracy between solvers and non-solvers, before and after the first cue to the solution (i.e., the first time they pulled the string opening the door). We finally compared accuracy over consecutive entrances for solvers. Using 884 observations from 788 great tits tested from 2010 to 2015, we showed that, prior to initial successful entrance, solvers were more accurate and more explorative than non-solvers, and that females were more likely to solve the task than males. The accuracy of solvers, but not of non-solvers, increased significantly after they had the opportunity to associate string pulling with the movement of the door, giving them a first cue to the task solution. The accuracy of solvers also increased over successive entrances. Our results demonstrate that variations in problem-solving performance primarily reflect inherent individual differences in associative learning, and are also to a lesser extent shaped by sex and exploratory behaviour.

Algorithmic assessment of shoulder function using smartphone video capture and machine learning

Tears within the stabilizing muscles of the shoulder, known as the rotator cuff (RC), are the most common cause of shoulder pain—often presenting in older patients and requiring expensive advanced imaging for diagnosis. Despite the high prevalence of RC tears within the elderly population, there is no previously published work examining shoulder kinematics using markerless motion capture in the context of shoulder injury. Here we show that a simple string pulling behavior task, where subjects pull a string using hand-over-hand motions, provides a reliable readout of shoulder mobility across animals and humans. We find that both mice and humans with RC tears exhibit decreased movement amplitude, prolonged movement time, and quantitative changes in waveform shape during string pulling task performance. In rodents, we further note the degradation of low dimensional, temporally coordinated movements after injury. Furthermore, a logistic regression model built on our biomarker ensemble succeeds in classifying human patients as having a RC tear with > 90% accuracy. Our results demonstrate how a combined framework bridging animal models, motion capture, convolutional neural networks, and algorithmic assessment of movement quality enables future research into the development of smartphone-based, at-home diagnostic tests for shoulder injury.

Automated system for training and assessing reaching and grasping behaviors in rodents

BackgroundReaching, grasping, and pulling behaviors are studied across species to investigate motor control and problem solving. String pulling is a distinct reaching and grasping behavior that is rapidly learned, requires bimanual coordination, is ethologically grounded, and has been applied across species and disease conditions. New MethodHere we describe the PANDA system (Pulling And Neural Data Analysis), a hardware and software system that integrates a continuous string loop connected to a rotary encoder, feeder, microcontroller, high-speed camera, and analysis software for the assessment and training of reaching, grasping, and pulling behaviors and synchronization with neural data. ResultsWe demonstrate this system in rats implanted with electrodes in motor cortex and hippocampus and show how it can be used to assess relationships between reaching, pulling, and grasping movements and single-unit and local-field activity. Furthermore, we found that automating the shaping procedure significantly improved performance over manual training, with rats pulling > 100 m during a 15-minute session. Comparison with Existing MethodsString-pulling is typically shaped by tying food reward to the string and visually scoring behavior. The system described here automates training, streamlines video assessment with deep learning, and automatically segments reaching movements into distinct reach/pull phases. No system, to our knowledge, exists for the automated shaping and assessment of this behavior. ConclusionsThis system will be of general use to researchers investigating motor control, motivation, sensorimotor integration, and motor disorders such as Parkinson's disease and stroke.

Information-theory analysis of mouse string-pulling agrees with Fitts’s Law: Increasing task difficulty engages multiple sensorimotor modalities in a dual oscillator behavior

Mouse string pulling, in which a mouse reels in a string with hand-over-hand movements, can provide insights into skilled motor behavior, neurological status, and cognitive function. The task involves two oscillatory movements connected by a string. The snout oscillates to track the pendulum movement of the string produced by hand-over-hand oscillations of pulling, and so the snout guides the hands to grasp the string. The present study examines the allocation of time required to pull strings of varying diameter. Movement is also described with end-point measures, string-pulling topography with 2D markerless pose estimates based on transfer learning with deep neural networks, and Mat-lab image-segmentation and heuristic algorithms for object tracking. With reduced string diameter, mice took longer to pull 60 cm long strings. They also made more pulling cycles, misses, and mouth engagements, and displayed changes in the amplitude and frequency of pull cycles. The time measures agree with Fitts’s law in showing that increased task difficulty slows behavior and engages multiple compensatory sensorimotor modalities. The analysis reveals that time is a valuable resource in skilled motor behavior and information-theory can serve as a measure of its effective use.

Data Partition and Rate Control for Learning and Energy Efficient Edge Intelligence

The rapid development of artificial intelligence together with the powerful computation capabilities of the advanced edge servers make it possible to deploy learning tasks at the wireless network edge, which is dubbed as edge intelligence (EI). The communication bottleneck between the data resource and the server results in deteriorated learning performance as well as tremendous energy consumption. To tackle this challenge, we explore a new paradigm called learning-and-energy-efficient (LEE) EI, which simultaneously maximizes the learning accuracies and energy efficiencies of multiple tasks via data partition and rate control. Mathematically, this results in a multi-objective optimization problem. Moreover, the continuously varying communication rates introduce infinite variables, which further complicates the problem. To solve this complex problem, we consider the case with infinite server buffer capacity and one-shot data arrival at sensor. First, the number of variables is reduced to a finite level by exploiting the optimality of constant-rate transmission in each epoch. Second, the optimal solution of the multi-objective problem is found by applying the stratified sequencing or merging of objectives. By assuming higher priority of learning efficiency in stratified sequencing, the optimal data partition is derived in closed form by the Lagrange method, while the optimal rate control is proved to have the structure of directional water filling (DWF), based on which a string-pulling (SP) algorithm is proposed to obtain the numerical values. The DWF structure of rate control is also proved to be optimal in merging of objectives, which combines different objectives in a weighted manner. By exploiting the optimal rate changing properties, the SP algorithm is further extended to tackle the more challenging cases with limited server buffer capacity or bursty data arrival at sensor. The performance of the proposed joint data partition and rate control design is examined by extensive experiments based on public datasets.

Therapeutic hypothermia demonstrates sex-dependent improvements in motor function in a rat model of neonatal hypoxic ischemic encephalopathy

Neonatal hypoxic ischemic encephalopathy (HIE) is a neurological disease caused by restricted oxygen and blood flow to the brain at or around the time of birth. Long term cognitive and motor sequelae are common and demonstrate sexual dimorphism in animal studies. Therapeutic hypothermia (TH) is the standard of care for HIE, but provides incomplete neuroprotection. Using the Vannucci model of neonatal HIE, term-equivalent 11-day old rat pups were subjected to mild-moderate hypoxic-ischemic injury (HII), and a subset of animals were treated with TH. Sex-dependent neuroprotection was measured with gross and fine motor control assays, and functional deficits detected with these assays were correlated to injury in specific brain structures. At the equivalent of human adolescence and adulthood (P51–89), accelerod and beam walking tests were used to assess gross motor function, and string-pulling and food handling tests were used to assess fine motor function. At necropsy (P94–97), brain lesions were primarily focused to the posterior cerebrum and characterized by variable reduction in cortical, thalamic and hippocampal regions and glial scarring. Gross motor impairment was detected in male rats with untreated and TH-treated HIE in the accelerod test, but beam walk test data was confounded by the lower body mass of untreated male rats. HIE animals of both sexes demonstrated deficit in the forelimb contralateral to ischemic surgery, observed as unilaterally impaired food handling behaviors, and in string pulling as decreased string contacts and increased in bracing behavior. However, kinematic analyses revealed sex-specific decreases in peak speeds in string reaching and pulling movements. In both sexes, treatment with TH improved body mass, some measures of contralateral forelimb impairment, and the severity of brain lesions to levels not different to Sham surgery rats. Unique differences in behavior following TH were observed in female rats, who took longer to consume food items but traversed beams and approached strings faster than untreated and Sham females. Future use of these motor assays may unravel the subtle, sex-specific differences in HIE outcomes and in developing a customized therapeutic approach to neonatal brain injury.

Toward a String-Pulling Approach to Path Smoothing on Grid Graphs

Paths found on grid graphs are often unrealistic looking in the continuous environment that the grid graph represents and often need to be smoothed after a search. The well-known algorithm for path smoothing is greedy in nature and does not necessarily eliminate all heading changes in freespace. We present a new path-smoothing algorithm based on “string pulling” and show experimentally that it consistently finds shorter paths than the greedy algorithm and produces paths with no heading changes in freespace.

Assessing Behavioral Impairment after Doxorubicin Chemotherapy in Rats

Chemotherapy has been associated with deficits in cognition and memory, delayed processing speed and executive function which may remain in patients as a long-term neurological effects. In addition, it also causes the disruption of hippocampal cell proliferation and neurogenesis, increased oxidative stress, and disruption in white matter. The cellular mechanisms linked with these side effects are poorly understood until now. Doxorubicin is Anthracycline agent that adversely affects the hippocampal neurogenesis and induces apoptosis by increasing oxygen radicals. It is considered first line therapy treatment for the most common cancers like breast, ovarian, and bladder. Young adult female Long Evans Hooded rats were divided into Doxorubicin treated (6mg/kg IP injection; once weekly for 4 weeks) and control groups (IP injection of sterile 0.9% saline on same schedule). We utilized the string pulling task, skilled ladder rung walking task, and other standard cognitive tests. We also performed immunohistochemistry to examine markers of inflammation related to chemotherapy and the extent to which chemotherapy would affect the process of neurogenesis. The results of the experiment we performed will be presented at the meeting and represent preliminary data for future studies.

Watch this tiny spider grab a bug 50 times its weight, thanks to some fancy string pulling

Watch this tiny spider grab a bug 50 times its weight, thanks to some fancy string pulling

Individual and social factors affecting the ability of American crows to solve and master a string pulling task.

Crows and other birds in the family Corvidae regularly share information to learn the identity and whereabouts of dangerous predators, but can they use social learning to solve a novel task for a food reward? Here we examined the factors affecting the ability of 27 wild-caught American crows to solve a common string-pulling task in a laboratory setting. We split crows into two groups; one group was given the task after repeatedly observing a conspecific model the solution, the other solved in the absence of conspecific models. We recorded the crows' estimated age, sex, size, body condition, level of nervousness, and brain volume using DICOM images from a CT scan. Although none of these variables were statistically significant, crows without a conspecific model and large brain volumes consistently mastered the task in the minimum number of days, whereas those with conspecific models and smaller brain volumes required varying and sometimes a substantial number of days to master the task. We found indirect evidence that body condition might also be important for motivating crows to solve the task. Crows with conspecific models were no more likely to initially solve the task than those working the puzzle without social information, but those that mastered the task usually copied the method most frequently demonstrated by their knowledgeable neighbors. These findings suggest that brain volume and possibly body condition may be factors in learning new tasks, and that crows can use social learning to refine their ability to obtain a novel food source, although they must initially learn to access it themselves.

Human string-pulling with and without a string: movement, sensory control, and memory.

String-pulling is a behavior that is allied to many daily acts and is an easily performed action featuring hand-over-hand movements to reel in a string (or rope). String-pulling has been used as a test of perceptual and cognitive functions in many animal species, including human children, but its movements and sensory control have not been characterized. Male and female university students (n = 68) performed target-based or memory-based string-pulling in which they pulled down a string suspended on an overhead pulley and immediately afterwards attempted to make the same movement in a memory-based test. Frame-by-frame video scoring was used to describe movements, eye-tracking and visual occluding glasses were used to assess sensory control, and a Matlab video-analysis procedure was used to describe kinematics. The string was advanced using five arm/hand movements: with lift and advance comprising fast up movements, and grasp, pull and push comprising slow down movements. Fingers closed 5 (pinky) through 1 (thumb) to make a whole-hand grasp and release in target-based string pulling but moved in a reverse sequence for the memory-based task. Target-based string pulling was not visually guided unless participants were instructed to grasp at a cue, and then vision featured eye-tracking of the target and pupil dilation with the grasp, but there was no relation between eye events for memory-based string-pulling. For target-based string-pulling the left and right hands advanced the string with both independent and concurrent movement but only independent movements were featured in a more symmetrical memory-based movement. The results are discussed in relation to the sensory control of hand movements, contemporary theories of the neural control of hand movements, and species differences in string-pulling.

Mechanisms underlying string-pulling behaviour in green-winged macaws

Abstract The string-pulling test is a classic test of physical cognition which is thought to examine an animal’s understanding of means-end comprehension, but may also result from trial and error learning. Here, we presented Green-winged macaws (Ara chloroptera) with a standard pull-up, and an alternative, pull-down, string pulling test to better understand the processes involved. Birds were divided into two groups: the experimental group were presented with the classic pull-up test and, upon completion, with the pull-down test, while the control group were only presented with the pull-down test. Six experimental birds solved the pull-up test, although none successfully completed the pull-down test; however, birds from the experimental group made significantly more pull-down actions than those from the control group. Together with previous findings on string-pulling behaviour in green-winged macaws, the results from the present study suggest that string-pulling behaviour in this species does not involve means-end understanding.

Unilateral forelimb sensorimotor cortex devascularization disrupts the topographic and kinematic characteristics of hand movements while string-pulling for food in the rat

String-pulling by the rat is a bimanual act, in which an upright animal retrieves a piece of food attached to the end of the string by downward hand-over-hand movements. The present study compared the movements of string-pulling, using topographic and kinematic measures of hand movement, in control rats and rats with unilateral sensorimotor motor cortex lesion produced by removal of the pia matter. In the first week following devascularization, the rhythmicity and accuracy of string-pulling movements decomposed; however, thereafter the rhythm of bilateral alternation was restored. Over 70days of testing, distance traveled decreased for both hands in the control and lesion groups, suggesting that both groups displayed an increase in string-pulling efficiency. Nevertheless, the lesion group exhibited more missed string contacts with the (contralateral-to-lesion) hand and more grasps in which the string was hooked between the digits with both hands. In addition, an increase in mouth grasps was observed in the lesion group. Motion capture analyses revealed that the lesion group exhibited longer reach and withdraw movements and these movements were longer for the ipsilateral-to-lesion vs contralateral-to-lesion hand. Thus, although rhythmicity of string-pulling behavior recovers after sensorimotor cortex devascularization, the contralateral-to-lesion hand contributed less to string pulling and requires mouth grasps to stabilize the string for grasping. The results are discussed in relation to contemporary theories of the contributions of the forelimb motor cortex to skilled movement and the potential use of string-pulling as a therapy for brain injury.

Culture in bumblebees

A recommendation of: Alem S, Perry CJ, Zhu X, Loukola OJ, Ingraham T, Sovik E, Chittka L Associative Mechanisms Allow for Social Learning and Cultural Transmission of String Pulling in an Insect https://doi.org/10.1371/journal.pbio.1002564

Associative Mechanisms Allow for Social Learning and Cultural Transmission of String Pulling in an Insect.

Social insects make elaborate use of simple mechanisms to achieve seemingly complex behavior and may thus provide a unique resource to discover the basic cognitive elements required for culture, i.e., group-specific behaviors that spread from “innovators” to others in the group via social learning. We first explored whether bumblebees can learn a nonnatural object manipulation task by using string pulling to access a reward that was presented out of reach. Only a small minority “innovated” and solved the task spontaneously, but most bees were able to learn to pull a string when trained in a stepwise manner. In addition, naïve bees learnt the task by observing a trained demonstrator from a distance. Learning the behavior relied on a combination of simple associative mechanisms and trial-and-error learning and did not require “insight”: naïve bees failed a “coiled-string experiment,” in which they did not receive instant visual feedback of the target moving closer when tugging on the string. In cultural diffusion experiments, the skill spread rapidly from a single knowledgeable individual to the majority of a colony’s foragers. We observed that there were several sequential sets (“generations”) of learners, so that previously naïve observers could first acquire the technique by interacting with skilled individuals and, subsequently, themselves become demonstrators for the next “generation” of learners, so that the longevity of the skill in the population could outlast the lives of informed foragers. This suggests that, so long as animals have a basic toolkit of associative and motor learning processes, the key ingredients for the cultural spread of unusual skills are already in place and do not require sophisticated cognition.

How far will a behaviourally flexible invasive bird go to innovate?

Behavioural flexibility is considered a key factor in the ability to adapt to changing environments. A traditional way of characterizing behavioural flexibility is to determine whether individuals invent solutions to novel problems, termed innovativeness. Great-tailed grackles are behaviourally flexible in that they can change their preferences when a task changes using existing behaviours; however, it is unknown how far they will go to invent solutions to novel problems. To begin to answer this question, I gave grackles two novel tests that a variety of other species can perform: stick tool use and string pulling. No grackle used a stick to access out-of-reach food, even after seeing a human demonstrate the solution. No grackle spontaneously pulled a vertically oriented string, but one did pull a horizontally oriented string twice. Additionally, a third novel test was previously conducted on these individuals and it was found that no grackle spontaneously dropped stones down a platform apparatus to release food, but six out of eight did become proficient after training. These results support the idea that behavioural flexibility is a multi-faceted trait because grackles are flexible, but not particularly innovative. This contradicts the idea that behavioural flexibility and innovativeness are interchangeable terms.

Cholinergic deafferentation of the hippocampus causes non-temporally graded retrograde amnesia in an odor discrimination task

Dementia of the Alzheimer’s type (DAT) is a neurodegenerative disorder marked by loss of hippocampal cholinergic tone and significant memory impairments, specifically for memories acquired prior to disease onset. The nature of this relationship, however, remains debated. The current study used the string pulling task to evaluate the temporal effects of odor discrimination learning in animals with selective cholinergic lesions to determine the role of the septohippocampal cholinergic system in mnemonic function. Rats with 192-IgG-Saporin lesions to the medial septum had a higher number of correct responses in the reversal training when compared to sham rats, suggesting an inability to retrieve the previously learned discrimination; however, no temporal gradient was observed. Furthermore, there were no group differences when learning a novel odor discrimination, demonstrating the ability for all rats to form new memories. These results establish a role for the cholinergic medial septum projections in long-term memory retrieval. The current study provides a behavioral assessment technique to investigate factors that influence mnemonic deficits associated with rodent models of DAT.

Cooperation in wild Barbary macaques: factors affecting free partner choice.

A key aspect of cooperation is partner choice: choosing the best available partner improves the chances of a successful cooperative interaction and decreases the likelihood of being exploited. However, in studies on cooperation subjects are rarely allowed to freely choose their partners. Group-living animals live in a complex social environment where they can choose among several social partners differing in, for example, sex, age, temperament, or dominance status. Our study investigated whether wild Barbary macaques succeed to cooperate using an experimental apparatus, and whether individual and social factors affect their choice of partners and the degree of cooperation. We used the string pulling task that requires two monkeys to manipulate simultaneously a rope in order to receive a food reward. The monkeys were free to interact with the apparatus or not and to choose their partner. The results showed that Barbary macaques are able to pair up with a partner to cooperate using the apparatus. High level of tolerance between monkeys was necessary for the initiation of successful cooperation, while strong social bond positively affected the maintenance of cooperative interactions. Dominance status, sex, age, and temperament of the subjects also affected their choice and performance. These factors thus need to be taken into account in cooperative experiment on animals. Tolerance between social partners is likely to be a prerequisite for the evolution of cooperation.

Study of Hamadryas Baboons (Papio Hamadryas) Ability to Solve Object Manipulation Tasks.

Cognitive ability to solve object manipulation tasks was evaluated by "string pulling" and "transparent tube" tests. The string pulling task was solved by 7 of 11 animals. The task of object extraction from the tube was too difficult, not a single animal solved it. The authors conclude that Hamadryas baboons demonstrated rather poor ability to solve object manipulation tasks.

The string-pulling paradigm in comparative psychology.

String pulling is one of the most widely used paradigms in comparative psychology. First documented 2 millennia ago, it has been a well-established scientific paradigm for a century. More than 160 bird and mammal species have been tested in over 200 studies with countless methodological variations. The paradigm can be used to address a wide variety of issues on animal cognition; for example, what animals understand about contact and connection as well as whether they rely on perceptual feedback, grasp the functionality of strings, generalize across conditions, apply their knowledge flexibly, and possess insight. Mammals are typically tested on a horizontal configuration, birds on a vertical one, making the studies difficult to compare; in particular, pulling a string vertically requires better coordination and attention. A species' performance on the paradigm is often influenced by its ecology, especially concerning whether limbs are used for foraging. Many other factors can be of importance and should be considered. The string-pulling paradigm is easy to administer, vary, and apply to investigate a wide array of cognitive abilities. Although it can be and has been used to compare species, divergent methods and unclear reporting have limited its comparative utility. With increasing research standards, the paradigm is expected to become an even more fundamental tool in comparative psychology.