Maison de Verre

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Children's ability to generate novel actions

Social learning has given us insight into how children learn actions from others across different domains (e.g., actions on objects, pretend play, and tool use). However, little research exists to confirm whether young children can generate their own novel actions. Three different settings were chosen to offer a varied investigation of children’s ability to generate novel actions: generating multiple actions with novel objects; generating iconic gestures in order to communicate; and generating pretend actions using object substitution. Generating multiple actions with novel objects: The Unusual Box test was developed to investigate children’s ability to generate multiple actions with novel objects (Chapter 2). The Unusual Box test involves children playing with a wooden box that contains many different features (e.g., rings, stairs, strings), and five novel objects. The number of different actions performed on the box and with the objects (i.e., fluency) was used as a measure of their individual learning. Positive correlations between the fluency scores of 24 3- and 4-year-olds on the Unusual Box test and two existing measures of divergent thinking were found. Divergent thinking relates to the ability to think of multiple answers based on one premise. Furthermore, a large range of fluency scores indicated individual differences in children’s ability to generate multiple actions with novel objects. In addition, 16 2-year-olds were assessed on the Unusual Box test, twice two weeks apart, to investigate test-retest reliability and the possibility that the Unusual Box test could be used with children younger than 3 years. A strong positive correlation between the scores on the two assessments showed high test-retest reliability, while individual differences in fluency scores and the absence of a floor effect indicated that the Unusual Box test was usable in children from 2 years of age. Generating iconic gestures in order to communicate: Children’s ability to generate iconic gestures in order to communicate was assessed using a game to request stickers from an experimenter (N = 20, Chapter 3). In order to get a sticker children had to communicate to the experimenter which out of two objects they wanted (only one object had a sticker attached to it). Children’s use of speech or pointing was ineffective; therefore only generating an iconic gesture was sufficient to retrieve the sticker. Children generated a correct iconic gesture on 71% of the trials. These findings indicate that children generate their own iconic gestures in order to communicate; and that they understand the representational nature of iconic gestures, and use this in their own generation of iconic gestures. Generating pretend actions using object substitution: In order to determine whether children are able to generate their own object substitution actions and understand the representational nature of these actions, 45 3- and 4-year-olds were familiarized with the goal of a task through modelling actions. Children distinguished between the intentions of an experimenter to pretend, or try and perform a correct action. Children mainly imitated the pretend actions, while correcting the trying actions. Next, children were presented with objects for which they had to generate their own object substitution actions without being shown a model. When children had previously been shown pretend actions, children generated their own object substitution actions. This indicates that children generate their own object substitution actions, and that they understand the representational nature of these actions. An additional study with 34 3-year-olds, revealed no significant correlations between divergent thinking, inhibitory control, or children’s object substitution in a free play setting, and children’s ability to generate object substitution actions in the experimental setting

Automatic imitation effects are influenced by experience of synchronous action in children

By their fourth year children are expert imitators but it is unclear how this ability develops. One approach suggests that certain types of experience might forge associations between the sensory and motor representations of an action that might facilitate imitation at a later time. Sensorimotor experience of this sort may occur when an infant’s action is imitated by a caregiver or when socially synchronous action occurs. This learning approach therefore predicts that the strength of sensory-motor associations should depend on the frequency and quality of previous experience. Here, we tested this prediction by examining automatic imitation; i.e., the tendency of an action stimulus to facilitate the performance of that action and interfere with the performance of an incompatible action. We required children (aged between 3:8 and 7:11) to respond to actions performed by an experimenter (e.g., two hands clapping), with both compatible actions (i.e., two hands clapping) and incompatible actions (i.e., two hands waving) at different stages in the experimental procedure. As predicted by a learning account, actions thought to be performed in synchrony (i.e., clapping/waving) produced stronger automatic imitation effects when compared to actions where previous sensorimotor experience is likely to be more limited (e.g., pointing/hand closing). Furthermore, these automatic imitation effects were not found to vary with age, as both compatible and incompatible responses quickened with age. These findings suggest a role for sensorimotor experience in the development of imitative ability

Impact of medical treatment on the outcome of patients after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE: The rationale behind early aneurysm surgery in patients with subarachnoid hemorrhage (SAH) is the prevention of rebleeding as early as possible after SAH. In addition, by clipping the aneurysm as early as possible, one can apply treatment for cerebral ischemia more vigorously (induced hypertension) without the risk of rebleeding. Hypervolemic hemodilution is now a well-accepted treatment for delayed cerebral ischemia. We compared the prospectively collected clinical data and outcome of patients admitted to the intensive care unit in the period 1977 to 1982 with those of patients admitted in the period 1989 to 1992 to measure the effect of the change in medical management procedures on patients admitted in our hospital with SAH. METHODS: We studied 348 patients admitted within 72 hours after aneurysmal SAH. Patients with negative angiography results and those in whom death appeared imminent on admission were excluded. The first group (group A) consisted of 176 consecutive patients admitted from 1977 through 1982. Maximum daily fluid intake was 1.5 to 2 L. Hyponatremia was treated with fluid restriction (<1 L/24 h). Antihypertensive treatment with diuretic agents was given if diastolic blood pressure was >110 mm Hg. Patients in the second group (172 consecutive patients; group B) were admitted from 1989 through 1992. Daily fluid intake was at least 3 L, unless cardiac failure occurred. Diuretic agents and antihypertensive medications were avoided. Cerebral ischemia was treated with vigorous plasma volume expansion under intermittent monitoring of pulmonary wedge pressure, cardiac output, and arterial blood pressure, aiming for a hematocrit of 0.29 to 0.33. Aneurysm surgery was planned for day 12. RESULTS: Patients admitted in group B had less favorable characteristics for the development of cerebral ischemia and for good outcome when compared with patients in group A. Despite this, we found a significant decrease in the frequency of delayed cerebral ischemia in patients of group B treated with tranexamic acid (P=0.00005 by log rank test) and significantly improved outcomes among patients with delayed cerebral ischemia (P=0.006 by chi2 test) and among patients with deterioration from hydrocephalus (P=0.001 by chi2 test). This resulted in a significant improvement of the overall outcome of patients in group B when compared with those in group A (P=0.006 by chi2 test). The major cause of death in group B was rebleeding (P=0.011 by chi2 test). CONCLUSIONS: We conclude that the outcome in our patients with aneurysmal SAH was improved but that rebleeding remains a major cause o

Modulation of calcium oxalate monohydrate crystallization kinetics in vitro

Modulation of calcium oxalate monohydrate crystallization kinetics in vitro. The effects of several low and high molecular weight (mol wt) compounds on the kinetics of calcium oxalate crystallization were examined using a seeded crystal growth method in which the solubility, the growth and the agglomeration of calcium oxalate crystals were measured as three separate and system-independent parameters. Git-rate, magnesium, phosphate, pyrophosphate, chondroitinsulphate, pen-tosanpolysulphate and heparin were tested in a wide range of concentrations. The solubility of calcium oxalate crystals Was increased only by citrate and magnesium. The crystal growth was inhibited by all compounds tested, but those with the high mol wt had the greatest effect at low concentrations. In contrast, inhibition of crystal agglomeration was achieved only by the low mol wt compounds; citrate was found to be the most potent inhibitor at concentrations likely to be present in normal urine. The high mol wt substances, despite their potent crystal growth inhibitory activity, had no effect on agglomeration. The results show that growth and agglomeration of calcium oxalate crystals are separate processes which are differently modulated by various compounds. They further provide a possible explanation for the pathogenetic role of citrate in hypocitraturic renal stone disease

Preschoolers understand and generate pretend actions using object substitution

Pretend play is often considered to be an imaginative or creative activity. Yet past experimental research has focused on whether children imitate pretense, follow instructions to pretend, or understand others’ pretense. Thus we cannot be sure that children’s pretense is in fact novel, or whether they simply copy or follows others’ instructions. This is the first experiment to show preschoolers generate their own novel object substitutions. In Study 1, 45 3- and 4-year-olds saw an experimenter use one object as another, accompanied by pretend or trying cues. Children differentiated between the experimenter’s intentions by imitating the actions accompanied by pretend cues, and correcting the actions accompanied by trying cues. Additionally, when the experimenter made her intentions to pretend or try explicit, children produced significantly more novel object substitutions not modeled or verbally requested by the experimenter within a pretend context than within a trying context. Study 2 replicated these findings with 34 3-year-olds using a repeated-measures design. However, it found no relationship between children’s copying or generation of object substitutions and: divergent thinking, inhibitory control, or pretense during free play

Individual differences and age-related changes in divergent thinking in toddlers and preschoolers

Divergent thinking shows the ability to search for new ideas, which is an important factor contributing to innovation and problem solving. Current divergent thinking tests allow researchers to study children's divergent thinking from the age of 3 years on. This article presents the first measure of divergent thinking that can be used with children as young as 2 years. The Unusual Box test is a nonverbal and nonimitative test in which children play individually with a novel toy and novel objects. Divergent thinking is scored as the number of different actions performed. Study 1 shows that the Unusual Box test is a valid measure of divergent thinking as it correlates with standard measures of divergent thinking in 3- and 4-year-olds. Study 2 indicates that the test can be used with 2-year-olds, as it shows high test-retest reliability, demonstrating that 2-year-olds can think divergently. Across both studies, individual differences and age-related changes were found, indicating that some children are better at divergent thinking than others and that children's divergent thinking increases with age. This test will allow researchers to gain insight into the early emergence of divergent thinking. © 2014 American Psychological Association

Optimal chartering decisions for vessel fleet to support offshore wind farm maintenance operations

Offshore wind energy is expected to be the most significant source of future electricity supply in Europe. Offshore wind farms are located far from the shores, requiring a fleet of various types of vessels to access sites when maintaining offshore wind turbines. The employment of the vessels is costly, accounting for the majority of the total O&M costs for offshore wind energy. Therefore, configuring the size and mix of the vessel fleet to support maintenance operations in a cost-effective manner is an issue of importance to enhance economics of offshore wind sector. In this paper, a discrete event simulation based model is proposed to present how a mixed vessel fleet with the specific configuration, including crew transfer vessels, field support vessels, and heavy lift vessels, performs maintenance for an offshore wind farm. The economic performance of the vessel fleet under a predetermined condition-based opportunistic maintenance strategy is investigated by using the model. A metaheuristic algorithm, simulated annealing, is employed to find the optimal fleet size and mix to make leasing decisions with the minimum costs. The performance of the developed approaches is evaluated by using a generic offshore wind farm in the North Sea. The sensitivity analysis is performed to investigate the most influential O&M factors