Experimental field study of hand preference in wild black-horned (<Emphasis Type="Italic">Cebus nigritus</Emphasis>) and white-faced (<Emphasis Type="Italic">Cebus capucinus</Emphasis>) capuchins: evidence for individual and species differences

In this experimental field investigation, we compare the degree to which wild capuchins in Brazil (Cebus nigritus) and Costa Rica (Cebus capucinus) exhibit individual- and population-level handedness during three visually-guided tasks. These tasks required reaching to remove a large leaf covering a hidden food reward, seizing the food reward, and manipulating a tool (pulling a wooden dowel) in order to obtain access to an embedded food reward. Studies in some populations of captive capuchins indicate evidence for both individual hand preferences and population-level handedness. In this study, six of eight wild C. capucinus and six of seven wild C. nigritus exhibited a significant hand preference during individual tasks, but no individual exhibited a consistent preference across all three tasks. Task-specialization, or the tendency for most individuals in the same group or population to use the same hand to accomplish a particular task, also was evaluated. Cebus nigritus showed a significant bias toward the use of the right hand in removing the leaf. Although the number of individual capuchins in both species that manipulated the dowels was limited (N = 7), each individual that manipulated the dowels in eight or more instances had a positive handedness index, suggesting a greater use of the right hand to accomplish this task. Overall, our results provide preliminary support for individual- and population-level handedness in wild capuchin monkeys.     

I know you are not looking at me: capuchin monkeys’ (<Emphasis Type="Italic">Cebus apella</Emphasis>) sensitivity to human attentional states

The present study asked whether capuchin monkeys recognize human attentional states. The monkeys requested food from the experimenter by extending an arm (pointing) toward the baited one of two transparent cups. On regular trials the experimenter gave the food immediately to the monkeys upon pointing but on randomly inserted test trials she ignored the pointing for 5 s during which she displayed different attentional states. The monkeys looked at the experimenter's face longer when she looked at the monkeys than when she looked at the ceiling in Experiment 1, and longer when she oriented her head midway between the two cups with eyes open than when she did so with eyes closed in Experiment 2. However, the monkeys showed no differential pointing in these conditions. These results suggest that capuchins are sensitive to eye direction but this sensitivity does not lead to differential pointing trained in laboratory experiments. Furthermore, to our knowledge, this is the first firm behavioral evidence that non-human primates attend to the subtle states of eyes in a food requesting task.     

Observing different model types interspersed with physical practice has no effect on consolidation or motor learning of an elbow flexion–extension task

We compared varied model types and their potential differential effects on learning outcomes and consolidation processes when observational practice was interspersed with physical practice. Participants (N = 75) were randomly assigned to one of five groups: (1) unskilled model observation, (2) skilled model observation, (3) mixed-model observation, (4) physical practice only, and (5) no observational or physical practice (control). All were tasked with learning a waveform-matching task. With exception of the control group not involved in acquisition sessions, participants were involved in one pre-test, two acquisition sessions, four retention tests (immediate-post acquisition 1, 24hr post acquisition 1, immediate-post acquisition 2, and approximate 7-day retention), as well as an approximate 7-day transfer test. No differences were demonstrated in consolidation processes or learning outcomes as all groups showed the same pattern of retention and transfer data. Our conclusion is that motor memory processes were not impacted differentially when different models types were used in observational practice that was intermixed with physical practice for the learning of a movement pattern with low task difficulty, and thus similar learning outcomes emerged for all groups.     

Capuchin monkeys (Cebus apella) succeed in a test of quantity conservation

Nonhuman animals demonstrate a number of impressive quantitative skills such as counting sets of items, comparing sets on the basis of the number of items or amount of material, and even responding to simple arithmetic manipulations. In this experiment, capuchin monkeys were presented with a computerized task designed to assess conservation of discrete quantity. Monkeys first were trained to select from two horizontal arrays of stimuli the one with the larger number of items. On some trials, after a correct selection there was no feedback but instead an additional manipulation of one of those arrays. In some cases, this manipulation involved moving items closer together or farther apart to change the physical arrangement of the array but not the quantity of items in the array. In other cases, additional items were added to the initially smaller array so that it became quantitatively larger. Monkeys then made a second selection from the two arrays of items. Previous research had shown that rhesus monkeys (Macaca mulatta) succeeded with this task. However, there was no condition in that study in which items were added to the smaller array without increasing its quantity to a point where it became the new larger array. This new condition was added in the present experiment. Capuchin monkeys were sensitive to all of these manipulations, changing their selections when the manipulations changed which array contained the larger number of items but not when the manipulations changed the physical arrangement of items or increased the quantity in one array without also reversing which of the two arrays had more items. Therefore, capuchin monkeys responded on the basis of the quantity of items, and they were not distracted by non-quantitative manipulations of the arrays. The data indicate that capuchins are sensitive to simply arithmetic manipulations that involve addition of items to arrays and also that they can conserve quantity.     

Capuchin monkeys (Cebus apella) respond to video images of themselves

Many studies have used mirror-image stimulation in attempts to find self-recognition in monkeys. However, very few studies have presented monkeys with video images of themselves; the present study is the first to do so with capuchin monkeys. Six tufted capuchin monkeys were individually exposed to live face-on and side-on video images of themselves (experimental Phase 1). Both video screens initially elicited considerable interest. Two adult males looked preferentially at their face-on image, whereas two adult females looked preferentially at their side-on image; the latter elicited lateral movements and head-cocking. Only males showed communicative facial expressions, which were directed towards the face-on screen. In Phase 2 monkeys discriminated between real-time, face-on images and identical images delayed by 1 s, with the adult females especially preferring real-time images. In this phase both screens elicited facial expressions, shown by all monkeys. In Phase 3 there was no evidence of discrimination between previously recorded video images of self and similar images of a familiar conspecific. Although they showed no signs of explicit self-recognition, the monkeys’ behaviour strongly suggests recognition of the correspondence between kinaesthetic information and external visual effects. In species such as humans and great apes, this type of self-awareness feeds into a system that gives rise to explicit self-recognition.     

Demonstrator skill modulates observational aversive learning

Learning to avoid danger by observing others can be relatively safe, because it does not incur the potential costs of individual trial and error. However, information gained through social observation might be less reliable than information gained through individual experiences, underscoring the need to apply observational learning critically. In order for observational learning to be adaptive it should be modulated by the skill of the observed person, the demonstrator. To address this issue, we used a probabilistic two-choice task where participants learned to minimize the number of electric shocks through individual learning and by observing a demonstrator performing the same task. By manipulating the demonstrator’s skill we varied how useful the observable information was; the demonstrator either learned the task quickly or did not learn it at all (random choices). To investigate the modulatory effect in detail, the task was performed under three conditions of available observable information; no observable information, observation of choices only, and observation of both the choices and their consequences. As predicted, our results showed that observable information can improve performance compared to individual learning, both when the demonstrator is skilled and unskilled; observation of consequences improved performance for both groups while observation of choices only improved performance for the group observing the skilled demonstrator. Reinforcement learning modeling showed that demonstrator skill modulated observational learning from the demonstrator’s choices, but not their consequences, by increasing the degree of imitation over time for the group that observed a fast learner. Our results show that humans can adaptively modulate observational learning in response to the usefulness of observable information.     

Object retrieval through observational learning in 8- to 18-month-old infants

Observational learning was studied in 8-, 10-, 12-, 15- and 18-month-old infants. Using object-retrieval tasks of relatively comparable difficulty for each age group, we showed that between 10 and 12 months there is a change in the capacity to learn a new skill by observation.     

Observation and physical practice: Coding of simple motor sequences

An experiment was conducted to determine the coordinate system used in the development of movement codes during observation and utilized on later physical practice performance of a simple spatial–temporal movement sequence. The task was to reproduce a 1.3-s spatial–temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two transfer tests was used: a mirror transfer test where the same pattern of muscle activation and limb joint angles was required and a nonmirror transfer test where the visual–spatial pattern of the sequence was reinstated on the transfer test. The results indicated a strong advantage for participants in the physical practice condition when transferred to the mirror condition in which the motor coordinates (e.g., pattern of muscle activation and joint angles) were reinstated relative to transfer performance when the visual–spatial coordinates were reinstated (visual and spatial location of the target waveform). The observation group, however, demonstrated an advantage when the visual–spatial coordinates were reinstated. These results demonstrate that codes based in motor coordinates can be developed relatively quickly for simple rapid movement sequences when participants are provided physical practice, but observational practice limits the system to the development of codes based in visual–spatial coordinates. Performances of control participants, who were not permitted to practise or observe the task, were quite poor on all tests.     

Scheduling observational and physical practice: Influence on the coding of simple motor sequences

The main purpose of the present experiment was to determine the coordinate system used in the development of movement codes when observational and physical practice are scheduled across practice sessions. The task was to reproduce a 1,300-ms spatial–temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two effector (contralateral limb) transfer tests was used. The mirror effector transfer test required the same pattern of homologous muscle activation and sequence of limb joint angles as that performed or observed during practice, and the nonmirror effector transfer test required the same spatial pattern movements as that performed or observed. The test results following the first acquisition session replicated the findings of Gruetzmacher, Panzer, Blandin, and Shea (2011) Gruetzmacher, N., Panzer, S., Blandin, Y. and Shea, C. H. 2011. Observation and coding of simple motor sequences. Quarterly Journal of Experimental Psychology, 64: 1111–1123. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]. The results following the second acquisition session indicated a strong advantage for participants who received physical practice in both practice sessions or received observational practice followed by physical practice. This advantage was found on both the retention and the mirror transfer tests compared to the nonmirror transfer test. These results demonstrate that codes based in motor coordinates can be developed relatively quickly and effectively for a simple spatial–temporal movement sequence when participants are provided with physical practice or observation followed by physical practice, but physical practice followed by observational practice or observational practice alone limits the development of codes based in motor coordinates.     

A comparison of intra- and inter-limb relative motion information in modelling a novel motor skill

The importance of intra- and inter-limb relative motion in modelling a whole body coordination skill was examined. Participants were assigned to one of four groups: Full-Body point light model of a cricket bowler, INTRA-LIMB relative motion of the bowling arm, INTER-LIMB relative motions of the right and left wrists or NO-Relative motion, showing only the motions of the right wrist. During 60 acquisition trials, participants viewed the model five times before each 10-trial block. Retention was examined the following day. Although all groups improved on intra-limb coordination of the bowling arm, the INTRA-LIMB and FULL-BODY groups were more accurate than the INTER-LIMB group in acquisition, although these groups did not differ in retention. For inter-limb coordination, the three groups who received relative motion information performed more like the model than the NO-Relative motion group (even though the INTRA-LIMB group did not see the other limb). The amount of information within a display plays a constraining role on acquisition, perhaps more so than the type of information, such that the acquisition of coordination is more an emergent feature of observational learning, rather than a direct approximation of the model.     

Self-control and frequency of model presentation: Effects on learning a ballet passé relevé

The purpose of this experiment was to examine the combined effects of self-control and frequency of model presentation on learning a complex motor skill, i.e., ballet passé relevé. Before practice started self-control participants were asked to choose two viewings or six viewings (before practice and then every five trials) and the externally controlled groups were yoked to their self-control counterparts. All participants completed 15 acquisition trials followed by 5 trials for the immediate and 5 trials for the delayed retention tests 48 hours later. Dependent variables included cognitive representation scores, physical reproduction rankings, and balance time. Statistical analyses indicated that under limited physical practice conditions self-control and higher frequency of model presentation facilitated the development of cognitive representation and did not produce further benefits in movement reproductions and balance time. The results were discussed with respect to the social cognitive theory.     

Imitation of hierarchical structure versus component details of complex actions by 3- and 5-year-olds

We investigated developmental changes in the level of information children incorporate into their imitation when a model executes complex, hierarchically organized actions. A total of 57 3-year-olds and 60 5-year-olds participated, watching video demonstrations of an “artificial fruit” box being opened through a complex series of nine different steps. Half of each sample observed the same nine steps performed through either of two different, hierarchically organized procedures, whereas half witnessed differing component action details. Children were found to imitate at both levels but were more likely to copy at the higher hierarchical level than at the level of specific action details. Fidelity to hierarchical organization, but not to the imitation of specific detail, increased with age. However, variation in imitativeness across children at one of these levels did not predict imitativeness at the other level.     

Ten-month-olds' selective use of visual dimensions in category learning

There is now general consensus that infants can use several different visual properties as the basis for categorization. Nonetheless, little is known about when and whether infants can be guided by contextual information to select the relevant properties from amongst those available to them. We show here that by 10 months of age infants can be biased, through observational learning, to use one or the other of two object properties for classification. Two groups of infants watched an actress classifying objects by either shape (the Shape group) or surface pattern (the Pattern group). When subsequently presented with two test trials which contradicted either one or the other of the classification rules, infants in the two groups looked longer to the classification event that was incompatible with the rule that group had been familiarized to. These results are discussed with reference to the development of selective feature processing in infancy.     

Seeing how it’s done: matching conditions for observer rats (Rattus norvegicus) in the bidirectional control

In an attempt to increase the reliability of the demonstrator-consistent responding effect produced in the bidirectional control procedure, experiments 1–4 sought conditions that would magnify the matching effect. The aim was to produce a robust demonstrator-consistent responding effect in order that future analytic experiments could investigate the psychological processes responsible for this effect. The joystick responses of observer rats trained using the standard bidirectional control procedure parameters were compared with those of observers subject to conditions identified in the social learning literature as favourable for imitation. Unlike mice, observer rats in experiments 1 a and 1 b tended to push a joystick in the same direction as their demonstrators when the demonstrators were either familiar or unfamiliar males and females. Comparable demonstrator-consistent responding occurred following observation of a standard and a salient joystick response (experiment 2). Experiment 3 showed that the discriminative accuracy of a demonstrator’s responding was important for matching behaviour, and suggested that matching might be enhanced with more than the conventional single observation session. Experiment 4 confirmed that the bidirectional control effect is sensitive to the amount of observational experience; after six observation sessions, demonstrator-inconsistent responding occurs. The results of experiments 1–3 are, and those of experiment 4 are not, compatible with the hypothesis that demonstrator-consistent responding in the bidirectional control is caused by olfactory cues deposited by demonstrators on the joystick. Received: 29 May 2000 / Accepted after revision: 28 August 2000     

Learning from others’ mistakes in capuchin monkeys (<Emphasis Type="Italic">Cebus apella</Emphasis>)

We investigated whether tufted capuchin monkeys (Cebus apella) learn from others' mistakes. We prepared three kinds of transparent containers having the same appearance: one that could be opened by the lid, one that could be opened from the bottom, and one that could be opened either way. Using each of the first two one-way-open type containers, the monkeys were trained to copy the human demonstrator's action to open the container and obtain a piece of sweet potato contained therein. After this training, the demonstrator showed the monkeys an action that would open or fail to open the third, two-way-open type container. None of the monkeys reliably opened the container by spontaneously compensating for the demonstrator's failure (Experiment 1). In Experiment 2, the same subjects were trained to correct their own mistakes immediately after failure, before we introduced the same test as in Experiment 1. This experience did not result in subjects using the demonstrator's failure to produce a successful action. In Experiment 3, we placed two monkeys face to face. In this situation, the second monkey was presented with the container after the first monkey failed to open it. As a result, two capuchin monkeys capitalized on the partner's failure to correctly guide his/her behavior. Thus, the monkeys monitored not only the outcome of the others' action, but also that action per se. This result suggests that not only humans and apes, but also monkeys may understand the meaning of others' actions in social learning.     

Understanding the experimenter's intention improves 16-month-olds’ observational learning of the use of a novel tool

Our aim was to investigate why 16-month-old infants fail to master a novel tool-use action via observational learning. We hypothesized that 16-month-olds’ difficulties may be due to not understanding the goal of the observed action. To test this hypothesis, we investigated whether showing infants an explicit demonstration of the goal of the action before demonstrating the action would improve observational learning compared with a classic demonstration of the target action. We examined 16-month-old infants who observed a tool-use action consisting of grasping a rake-like tool to retrieve an out-of-reach toy, under five conditions. Only when infants were shown the goal of the action before demonstration did they show some success.     

Contexts of a person's prior intentions facilitate observational learning in 2.5-year-old children

We examined whether contexts suggesting an actor's prior intentions facilitate observational learning in 2.5-year-olds. In Experiment 1, children observed an experimenter handle one box before proceeding to open a second box. In two prior intention conditions, children either watched the experimenter extract a toy from the first box or saw that the box had already been opened. In two no prior intention conditions, children watched the demonstration with only the second box or paired with irrelevant actions upon the first box. Children successfully opened the second box more often in the two prior intention conditions than in the two no prior intention conditions. Experiment 2 investigated stimulus generalization as another explanation for these results. A functionally different trap-tube task served as the pre-demonstration apparatus. Before watching the experimenter open the box, children either saw her extract a toy from the tube with a stick or observed the toy accidentally fall from the opening. In both cases, children opened the box at similar high rates. We discuss children's use of others’ prior intentions or observable outcomes in observational learning.     

Combining Action Observation and Motor Imagery Improves Eye–Hand Coordination during Novel Visuomotor Task Performance

Abstract

In this study, we compared the effectiveness of concurrent action observation and motor imagery (AO?+?MI), observing with the intent to imitate (active observation; AO), and passive observation (PO) training interventions for improving eye–hand coordination. Fifty participants were assigned to five groups [AO?+?MI, AO, PO, physical practice (PP); control] and performed a visuomotor rotation task, whilst eye movements were recorded. Each participant then performed 20 task trials in a training intervention before repeating the visuomotor rotation task in a post-test. As expected, PP produced the greatest improvement in task performance and eye–hand coordination. However, in comparison to the control group, AO?+?MI training produced a statistically significant increase in both task performance and eye–hand coordination, but no such improvements were found following AO or PO.     

Effects of attentional-focus instructions on movement kinematics

BackgroundRecent research has shown that internal (body-related) attention-focus instructions disrupt motor learning and performance, whereas paying attention to the environmental effects of movements (external focus) leads to better performance than an internal focus [see, for reviews, Wulf, G. (2007). Attentional focus and motor learning: a review of 10 years of research. E-Journal Bewegung und Training, 1, 4–14.; Wulf, G., &; Prinz, W. (2001). Directing attention to movement effects enhances learning: a review. Psychonomic Bulletin &; Review, 8, 648–660.]. However, Beilock's studies [Beilock, S. L., Bertenthal, B. I., McCoy, A. M., &; Carr, T. H. (2004). Haste does not always make waste: expertise, direction of attention, and speed versus accuracy in performing sensorimotor skills. Psychonomic Bulletin &; Review, 11, 373–379.] suggest that an internal focus is detrimental in experts but not in novices. Because detrimental effects of consciously attending to movements have generally been measured by performance scores such as accuracy scores or reaction times, it remains unclear how internal and external attentional-focus instructions influence movement kinematics when learning a new skill. To fill this gap, the present study investigated attentional-focus effects on a biomechanical level.MethodsA video of an expert juggler demonstrating a two-ball juggling task was presented to juggling novices. Experimental groups were given either body-related (internal group) or ball-related (external group) verbal instructions or no attention-guiding instructions (control group). In the retention phase without attention-guiding instructions, the body-movement and ball-flight aspects of performance focused on in the verbal instruction were subjected to biomechanical analyses.Results and ConclusionsJuggling performance improved equally in all three groups. However, internally vs. externally instructed acquisition phases had differential effects on the kinematics of the upper body as well as ball trajectories when performing the juggling task. Remarkably, ball trajectories in the control group who received no specific attentional cueing were similar to those in the externally instructed group. This suggests that task-relevant information is picked up independently of instructions, and that external instructions provide redundant information. Internal instructions for object-related tasks, however, may confront novice learners with the need to process additional information. As a result, task difficulty might be unnecessarily enhanced in an observational learning setting.     

The role of stimulus preexposure in problem solving by Octopus vulgaris

Octopus vulgaris is able to open transparent glass jars closed with plastic plugs and containing live crabs. The decrease in performance times for removing the plug and seizing the prey with increasing experience of the task has been taken to indicate learning. However, octopuses’ attack behaviors are typically slow and variable in novel environmental situations. In this study the role of preexposure to selected features of the problem-solving context was investigated. Although octopuses failed to benefit from greater familiarity with the training context or with selected elements of the task of solving the jar problem, the methodological strategies used are instructive in potentially clarifying the role of complex problem-solving behaviors in this species including stimulus preexposure and social learning. Received: 27 April 1998 / Accepted after revision: 24 July 1998