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Web-based data collection is increasingly popular in both experimental and survey-based research because it is flexible, efficient, and location-independent. While dedicated software for laboratory-based experimentation and online surveys is commonplace, researchers looking to implement experiments in the browser have, heretofore, often had to manually construct their studies' content and logic using code. We introduce lab.js, a free, open-source experiment builder that makes it easy to build studies for both online and in-laboratory data collection. Through its visual interface, stimuli can be designed and combined into a study without programming, though studies' appearance and behavior can be fully customized using HTML, CSS, and JavaScript code if required. Presentation and response times are kept and measured with high accuracy and precision heretofore unmatched in browser-based studies. Experiments constructed with lab.js can be run directly on a local computer and published online with ease, with direct deployment to cloud hosting, export to web servers, and integration with popular data collection platforms. Studies can also be shared in an editable format, archived, re-used and adapted, enabling effortless, transparent replications, and thus facilitating open, cumulative science. The software is provided free of charge under an open-source license; further information, code, and extensive documentation are available from https://lab.js.org/ .
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Computadores , Software , Coleta de Dados , Humanos , Tempo de ReaçãoRESUMO
The following reference was omitted from this article.
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Investigating cognitive processes by analyzing mouse movements has become a popular method in many psychological disciplines. When creating mouse-tracking experiments, researchers face many design choices-for example, whether participants indicate responses by clicking a button or just by entering the button area. Hitherto, numerous different settings have been employed, but little is known about how these methodological differences affect mouse-tracking data. We systematically investigated the influences of three central design factors, using a classic mouse-tracking paradigm in which participants classified typical and atypical exemplars. In separate experiments, we manipulated the response indication, mouse sensitivity, and starting procedure. The core finding that mouse movements deviate more toward the nonchosen option for atypical exemplars was replicated in all conditions. However, the size of this effect varied. Specifically, it was larger when participants indicated responses via click and when they were instructed to initialize the movement early. Trajectory shapes also differed between setups. For example, a dynamic start led to mostly curved trajectories, responses via click led to a mix of straight and "change-of-mind" trajectories, and responses via touch led to mostly straight trajectories. Moreover, the distribution of curvature indices was classified as bimodal in some setups and as unimodal in others. Because trajectory curvature and shape are frequently used to make inferences about psychological theories, such as differentiating between dynamic and dual-system models, this study shows that the specific design must be carefully considered when drawing theoretical inferences. All methodological designs and analyses were implemented using open-source software and are available from https://osf.io/xdp7a/.
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Movimento , Adolescente , Adulto , Computadores , Feminino , Humanos , Masculino , Teoria Psicológica , Software , Tato , Adulto JovemRESUMO
Mouse-tracking is an increasingly popular process-tracing method. It builds on the assumption that the continuity of cognitive processing leaks into the continuity of mouse movements. Because this assumption is the prerequisite for meaningful reverse inference, it is an important question whether the assumed interaction between continuous processing and movement might be influenced by the methodological setup of the measurement. Here we studied the impacts of three commonly occurring methodological variations on the quality of mouse-tracking measures, and hence, on the reported cognitive effects. We used a mouse-tracking version of a classical intertemporal choice task that had previously been used to examine the dynamics of temporal discounting and the date-delay effect (Dshemuchadse, Scherbaum, & Goschke, 2013). The data from this previous study also served as a benchmark condition in our experimental design. Between studies, we varied the starting procedure. Within the new study, we varied the response procedure and the stimulus position. The starting procedure had the strongest influence on common mouse-tracking measures, and therefore on the cognitive effects. The effects of the response procedure and the stimulus position were weaker and less pronounced. The results suggest that the methodological setup crucially influences the interaction between continuous processing and mouse movement. We conclude that the methodological setup is of high importance for the validity of mouse-tracking as a process-tracing method. Finally, we discuss the need for standardized mouse-tracking setups, for which we provide recommendations, and present two promising lines of research toward obtaining an evidence-based gold standard of mouse-tracking.
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Desvalorização pelo Atraso , Adulto , Benchmarking , Computadores , Feminino , Humanos , Masculino , Processos Mentais , Movimento , Projetos de Pesquisa , Adulto JovemRESUMO
Mouse-tracking is an increasingly popular method to trace cognitive processes. As is common for a novel method, the exact methodological procedures employed in an individual study are still relatively idiosyncratic and the effects of different methodological setups on mouse-tracking measures have not been explored so far. Here, we study the impact of one commonly occurring methodological variation, namely whether participants have to initiate their mouse movements to trigger stimulus presentation (dynamic starting condition) or whether the stimulus is presented automatically after a fixed delay and participants can freely decide when to initiate their movements (static starting condition). We compared data from a previous study in which participants performed a mouse-tracking version of a Simon task with a dynamic starting condition to data from a new study that employed a static starting condition in an otherwise identical setup. Results showed reliable Simon effects and Congruency Sequence effects on response time (RT) and discrete trial-level mouse-tracking measures (i.e., average deviation) in both starting conditions. In contrast, within-trial continuous measures (i.e., extracted temporal segments) were weaker and occurred in a more temporally compressed way in the static compared to the dynamic starting condition. This was in line with generally less consistent movements within and across participants in the static compared to the dynamic condition. Our results suggest that studies that use within-trial continuous measures to assess dynamic aspects of mouse movements should apply dynamic starting procedures to enhance the leakage of cognitive processing into the mouse movements.
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Periféricos de Computador , Movimento , Testes Psicológicos , Tempo de Reação , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Purpose To determine the effect of more than 20 serial injections of macrocyclic gadolinium-based contrast agents (GBCAs) on the signal intensity (SI) of the dentate nucleus (DN) on unenhanced T1-weighted magnetic resonance (MR) images. Materials and Methods In this retrospective, institutional review board-approved study, 33 patients who underwent at least 20 consecutive MR imaging examinations (plus an additional MR imaging for reference) with the exclusive use of macrocyclic GBCAs gadoterate meglumine and gadobutrol were analyzed. SI ratio differences were calculated for DN-to-pons and DN-to-middle cerebellar peduncle (MCP) ratios by subtracting the SI ratio at the first MR imaging examination from the SI ratio at the last MR imaging examination. One-sample t tests were used to examine if the SI ratio differences differed from 0, and Bayes factors were calculated to quantify the strength of evidence for each test. Results Patients underwent a mean of 23.03 ± (standard deviation) 4.20 GBCA administrations (mean accumulated dose, 491.21 mL ± 87.04 of a 0.5 M GBCA solution) with an average of 12.09 weeks ± 2.16 between every administration. Both ratio differences did not differ significantly from 0 (DN-to-pons ratio: -0.0032 ± 0.0154, P = .248; DN-to-MCP ratio: -0.0011 ± 0.0093, P = .521), and one-sided Bayes factors provided substantial to strong evidence against an SI ratio increase (Bayes factor for DN-to-pons ratio = 0.09 and that for DN-to-MCP ratio = 0.12). Conclusion The study indicates that 20 or more serial injections of macrocyclic GBCAs administered with on average 3 months between each injection are not associated with an SI increase in the DN. © RSNA, 2016.
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Núcleos Cerebelares/efeitos dos fármacos , Núcleos Cerebelares/diagnóstico por imagem , Meios de Contraste/farmacologia , Imageamento por Ressonância Magnética/métodos , Meglumina/farmacologia , Compostos Organometálicos/farmacologia , Adulto , Meios de Contraste/administração & dosagem , Feminino , Humanos , Aumento da Imagem , Injeções , Compostos Macrocíclicos/administração & dosagem , Masculino , Meglumina/administração & dosagem , Compostos Organometálicos/administração & dosagem , Estudos RetrospectivosRESUMO
Mouse-tracking - the analysis of mouse movements in computerized experiments - is becoming increasingly popular in the cognitive sciences. Mouse movements are taken as an indicator of commitment to or conflict between choice options during the decision process. Using mouse-tracking, researchers have gained insight into the temporal development of cognitive processes across a growing number of psychological domains. In the current article, we present software that offers easy and convenient means of recording and analyzing mouse movements in computerized laboratory experiments. In particular, we introduce and demonstrate the mousetrap plugin that adds mouse-tracking to OpenSesame, a popular general-purpose graphical experiment builder. By integrating with this existing experimental software, mousetrap allows for the creation of mouse-tracking studies through a graphical interface, without requiring programming skills. Thus, researchers can benefit from the core features of a validated software package and the many extensions available for it (e.g., the integration with auxiliary hardware such as eye-tracking, or the support of interactive experiments). In addition, the recorded data can be imported directly into the statistical programming language R using the mousetrap package, which greatly facilitates analysis. Mousetrap is cross-platform, open-source and available free of charge from https://github.com/pascalkieslich/mousetrap-os .
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Computadores , Software , Humanos , Linguagens de Programação , Projetos de PesquisaRESUMO
We introduce a novel platform for interactive studies, that is, any form of study in which participants' experiences depend not only on their own responses, but also on those of other participants who complete the same study in parallel, for example a prisoner's dilemma or an ultimatum game. The software thus especially serves the rapidly growing field of strategic interaction research within psychology and behavioral economics. In contrast to all available software packages, our platform does not handle stimulus display and response collection itself. Instead, we provide a mechanism to extend existing experimental software to incorporate interactive functionality. This approach allows us to draw upon the capabilities already available, such as accuracy of temporal measurement, integration with auxiliary hardware such as eye-trackers or (neuro-)physiological apparatus, and recent advances in experimental software, for example capturing response dynamics through mouse-tracking. Through integration with OpenSesame, an open-source graphical experiment builder, studies can be assembled via a drag-and-drop interface requiring little or no further programming skills. In addition, by using the same communication mechanism across software packages, we also enable interoperability between systems. Our source code, which provides support for all major operating systems and several popular experimental packages, can be freely used and distributed under an open source license. The communication protocols underlying its functionality are also well documented and easily adapted to further platforms. Code and documentation are available at https://github.com/psynteract/ .
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Jogos Experimentais , Projetos de Pesquisa , Software , HumanosRESUMO
PURPOSE: To compare changes in signal intensity (SI) ratios of the dentate nucleus (DN) and the globus pallidus (GP) to those of other structures on unenhanced T1-weighted magnetic resonance (MR) images between linear and macrocyclic gadolinium-based contrast agents (GBCAs). MATERIALS AND METHODS: The study was approved by the ethical committee of the University of Heidelberg (reference no. S-324/2014). Owing to the retrospective character of the study, the ethical committee did not require any written informed consent. Two groups of 50 patients who underwent at least six consecutive MR imaging examinations with the exclusive use of either a linear GBCA (gadopentetate dimeglumine) or a macrocyclic GBCA (gadoterate meglumine) were analyzed retrospectively. The difference in mean SI ratios of DN to pons and GP to thalamus on unenhanced T1-weighted images from the last and first examinations was calculated. One-sample and independent-sample t tests were used to assess the difference in SI ratios for both groups, and regression analysis was performed to account for potential confounders. RESULTS: The SI ratio difference in the linear group was greater than 0 (mean DN difference ± standard deviation, 0.0407 ± 0.0398 [P < .001]; GP, 0.0287 ± 0.0275 [P < .001]) and significantly larger (DN, P < .001 and standardized difference of 1.16; GP, P < .001 and standardized difference of 0.81) than that in the macrocyclic group, which did not differ from 0 (DN, 0.0016 ± 0.0266 [P = .680]; GP, 0.0031 ± 0.0354 [P = .538]). The SI ratio difference between the last and first examinations for the DN remained significantly different between the two groups in the regression analysis (P < .001). CONCLUSION: This study indicates that an SI increase in the DN and GP on T1-weighted images is caused by serial application of the linear GBCA gadopentetate dimeglumine but not by the macrocyclic GBCA gadoterate meglumine. Clinical implications of this observation remain unclear.
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Núcleos Cerebelares/metabolismo , Meios de Contraste/farmacocinética , Gadolínio DTPA/farmacocinética , Globo Pálido/metabolismo , Imageamento por Ressonância Magnética , Meglumina/farmacocinética , Compostos Organometálicos/farmacocinética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
Survey participants' mouse movements provide a rich, unobtrusive source of paradata, offering insight into the response process beyond the observed answers. However, the use of mouse tracking may require participants' explicit consent for their movements to be recorded and analyzed. Thus, the question arises of how its presence affects the willingness of participants to take part in a survey at all-if prospective respondents are reluctant to complete a survey if additional measures are recorded, collecting paradata may do more harm than good. Previous research has found that other paradata collection modes reduce the willingness to participate, and that this decrease may be influenced by the specific motivation provided to participants for collecting the data. However, the effects of mouse movement collection on survey consent and participation have not been addressed so far. In a vignette experiment, we show that reported willingness to participate in a survey decreased when mouse tracking was part of the overall consent. However, a larger proportion of the sample indicated willingness to both take part and provide mouse-tracking data when these decisions were combined, compared to an independent opt-in to paradata collection, separated from the decision to complete the study. This suggests that survey practitioners may face a trade-off between maximizing their overall participation rate and maximizing the number of participants who also provide mouse-tracking data. Explaining motivations for paradata collection did not have a positive effect and, in some cases, even reduced participants' reported willingness to take part in the survey.
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When making risky choices, people often fall short of the norm of expected value (EV) maximization. Previous research has shown that presenting options in the Open Sampling (OSa) format, a 10-by-10 matrix of randomly arranged outcomes, can improve choices and reduce decision times. First, the current research aims to replicate and extend the findings on the OSa format. To this end, we compare OSa to the common description-based format as well as further graphical representations, and investigate the resulting accordance with EV maximization and decision time. Second, we study whether people lower (vs. higher) in numeracy, the ability to use probabilistic and mathematical concepts, particularly benefit from a graphical representation of options. We conducted five high-powered studies (total N = 1,575) in which participants chose repeatedly between two risky gambles, using different populations and gamble-problem sets. Overall, we could not find a benefit of the OSa format in terms of EV accordance in any of the five studies. However, three studies also tested a novel variant of the OSa format with grouped outcomes and found that it consistently improved EV accordance compared with all other formats. All graphical formats led to faster decisions without harming decision quality. The effects of presentation format were not moderated by numeracy in three of the four studies that assessed numeracy. In conclusion, our research introduces a new presentation format which consistently improves risky choices and can also be used to communicate risks in applied contexts such as medical decision making.
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Jogo de Azar , Tomada de Decisões , Humanos , Conceitos MatemáticosRESUMO
Impression formation is vital for social interactions and theorized to be negatively biased in borderline personality disorder (BPD). We assessed 2 sides of impression formation in BPD: BPD individuals as raters who form first impressions and as targets of others' first impressions. We further investigated BPD-Rater × Target interactions. We showed videos of 52 targets (26 BPD, 26 healthy controls [HC], 46% male) to unmedicated women with BPD (n = 32), a clinical control group with social anxiety disorder (SAD; n = 29), and a HC group (n = 37). We hypothesized (a) that BPD raters would evaluate targets more negatively than SAD and HC raters. Indeed, BPD raters evaluated targets as significantly less trustworthy, less approachable, and less similar to themselves than HC raters. Descriptively, rater groups showed a pattern of BPD < SAD < HC, but the differences between SAD and both other rater groups failed to reach statistical significance. We further expected (b) HC raters to evaluate BPD targets more negatively than HC targets, and results supported this hypothesis. Lastly, we hypothesized (c) that BPD raters would perceive BPD targets more positively than HC targets, which was not supported. We discuss how negative first impressions by and of BPD individuals could contribute to loneliness and interpersonal dysfunction and suggest potential interventions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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Transtorno da Personalidade Borderline , Feminino , Humanos , Relações Interpessoais , Masculino , Interação SocialRESUMO
Individuals with Borderline Personality Disorder (BPD) or Social Anxiety Disorder (SAD) suffer from substantial interpersonal dysfunction and have difficulties establishing social bonds. A tendency to form negative first impressions of others could contribute to this by way of reducing approach behavior. We tested whether women with BPD or SAD would show negative impression formation compared to healthy women (HCs). We employed the Thin Slices paradigm and showed videos of 52 authentic target participants to 32 women with BPD, 29 women with SAD, and 37 HCs. We asked participants to evaluate whether different positive or negative adjectives described targets and expected BPD raters to provide the most negative ratings, followed by SAD and HC. BPD and SAD raters both agreed with negative adjectives more often than HCs (e.g., 'Yes, the person is greedy'), and BPD raters rejected positive adjectives more often (e.g., 'No, the person is not humble.'). However, BPD and SAD raters did not differ significantly from each other. Additionally, we used the novel process tracing method mouse-tracking to assess the cognitive conflict (via trajectory deviations) raters experienced during decision-making. We hypothesized that HCs would experience more conflict when making unfavorable (versus favorable) evaluations and that this pattern would flip in BPD and SAD. We quantified cognitive conflict via maximum absolute deviations (MADs) of the mouse-trajectories. As hypothesized, HCs showed more conflict when rejecting versus agreeing with positive adjectives. The pattern did not flip in BPD and SAD but was substantially reduced, such that BPD and SAD showed similar levels of conflict when rejecting and agreeing with positive adjectives. Contrary to the hypothesis for BPD and SAD, all three groups experienced substantial conflict when agreeing with negative adjectives. We discuss therapeutic implications of the combined choice and mouse-tracking results.
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Transtorno da Personalidade Borderline/fisiopatologia , Fobia Social/fisiopatologia , Adulto , Transtorno da Personalidade Borderline/epidemiologia , Transtorno da Personalidade Borderline/psicologia , Cognição , Feminino , Humanos , Relações Interpessoais , Pessoa de Meia-Idade , Fobia Social/epidemiologia , Fobia Social/psicologia , Percepção Social , Fatores Socioeconômicos , Adulto JovemRESUMO
From an embodiment perspective, action and cognition influence each other constantly. This interaction has been utilized in mouse-tracking studies to infer cognitive states from movements, assuming a continuous manifestation of cognitive processing into movement. However, it is mostly unknown how this manifestation is affected by the variety of possible design choices in mouse-tracking paradigms. Here we studied how three design factors impact the manifestation of cognition into movement in a Simon task with mouse tracking. We varied the response selection (i.e., with or without clicking), the ratio between hand and mouse cursor movement, and the location of the response boxes. The results show that all design factors can blur or even prevent the manifestation of cognition into movement, as reflected by a reduction in movement consistency and action dynamics, as well as by the adoption of unsuitable movement strategies. We conclude that deliberate and careful design choices in mouse-tracking experiments are crucial to ensuring a continuous manifestation of cognition in movement. We discuss the importance of developing a standard practice in the design of mouse-tracking experiments.
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Cognição/fisiologia , Percepção de Movimento/fisiologia , Movimento/fisiologia , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Adolescente , Adulto , Feminino , Mãos/fisiologia , Humanos , Masculino , Adulto JovemRESUMO
BACKGROUND: Several recent studies have demonstrated that naïve raters tend to evaluate individuals with Borderline Personality Disorder (BPD) negatively at zero-acquaintance (i.e., in a 'first impression' type situation, where the rater has no knowledge of the individual and no prior interactions with them). Specifically, individuals with BPD were evaluated as less trustworthy, likeable, and cooperative than healthy participants (HCs). Based on previous impression formation studies, we hypothesized that the non-verbal cues positive affect display, negative affect display, and eye contact contribute to negative first impressions of those with BPD. METHODS: To address this question, we recruited 101 participants that rated the degree of positive affect display, negative affect display, and eye contact in 52 videos of age-and gender-matched BPD and HC participants. We hypothesized that low positive affect display, high negative affect display, and eye contact would mediate the association between group (BPD vs. HC) and ratings of trustworthiness, likeability, and cooperativeness. RESULTS: Ratings for positive affect display were significantly lower and those for negative affect display significantly higher for BPD versus HC targets, whereas eye contact did not differ significantly between groups. In multiple mediation models, positive affect display significantly mediated the association between group and trustworthiness/likeability, whereas negative affect display only mediated the association between group and likeability. None of the individual cues was a significant mediator of the association between group and cooperation. CONCLUSIONS: We emphasize therapeutic possibilities to improve positive affect display -and thus overall first impressions- to increase the chances of forming social bonds for BPD individuals.
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Multinomial processing tree models assume that discrete cognitive states determine observed response frequencies. Generalized processing tree (GPT) models extend this conceptual framework to continuous variables such as response times, process-tracing measures, or neurophysiological variables. GPT models assume finite-mixture distributions, with weights determined by a processing tree structure, and continuous components modeled by parameterized distributions such as Gaussians with separate or shared parameters across states. We discuss identifiability, parameter estimation, model testing, a modeling syntax, and the improved precision of GPT estimates. Finally, a GPT version of the feature comparison model of semantic categorization is applied to computer-mouse trajectories.
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Cognição , Modelos Teóricos , Simulação por Computador , Computadores , Mãos , Humanos , Julgamento , Atividade Motora , Psicometria/métodos , Tempo de Reação , Reconhecimento Psicológico , SemânticaRESUMO
Previous research suggests that individuals with Borderline Personality Disorder (BPD) tend to evaluate other people as untrustworthy or hostile, which could contribute to the marked interpersonal problems in BPD. In contrast, alterations in first impressions of potential interaction partners of those with BPD remain under-researched and poorly understood. Herein, we focused on how naïve raters evaluate BPD individuals, hypothesizing that raters would tend to evaluate them negatively. To test this hypothesis, we recruited 26 BPD and 26 healthy control participants (46% male) as targets in the 'Thin Slices' paradigm. Targets were video-taped while talking about their personal preferences (e.g. hobbies). Subsequently, these short videos ('Thin Slices') were presented to two rater samples (nâ¯=â¯92 and nâ¯=â¯44), who evaluated targets' likeability, trustworthiness, and cooperative behavior in an economic game. In both studies, raters evaluated BPD targets as less likeable and trustworthy, and in one study also as less cooperative. These findings are contrasted with results from an economic game, in which BPD targets behaved no less cooperatively than controls. We discuss limitations with regard to socioeconomic differences between the target groups and explore how negative evaluations by others may contribute to the interpersonal difficulties in BPD. We suggest that - given future replication with more strictly matched target groups- interventions aimed at improving impression management could be beneficial for BPD patients.
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Transtorno da Personalidade Borderline/psicologia , Relações Interpessoais , Percepção Social , Adolescente , Adulto , Estudos de Casos e Controles , Comportamento Cooperativo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Confiança , Gravação de Videoteipe , Adulto JovemRESUMO
In this study, we aimed to explore whether action execution is an inherent part of the decision-making process. According to the hypothesis of embodied choice, the decision-making process is bidirectional as action dynamics exert their backward influence on decision processes through changing the cost and value of the potential options. This influence takes place as moving toward one option increases the commitment to and, therefore, the likelihood of choosing that option. This commitment effect can be the result of either (a) the continuous act of getting closer to this option or (b) the increased movement cost associated with changing the movement direction to select a different option. To disentangle the potential influence of these two factors, we developed the Guided Movement Task, a choice task designed to bias participant's computer-mouse movements by constraining the allowed movement space by a corridor. Using this task, we created different conditions in which the participants' mouse cursor, after being guided toward one of the options, either had equal or unequal distances to the choice options. By this manipulation, we could test whether the continuous act of getting closer to an option in itself is sufficient to influence people's decisions-a claim of "strong embodiment." In two experiments, we found that the likelihood of choosing an option only increased when the distances between the two options were unequal after the initial movement but not when they were equal. These results disagree with the hypothesis that action execution is an inherent part of the decision-making process. (PsycINFO Database Record
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Tomada de Decisões , Atividade Motora , Desempenho Psicomotor , Feminino , Humanos , Masculino , Teoria Psicológica , Adulto JovemRESUMO
PURPOSE: To correlate histopathologic findings from biopsy specimens with their corresponding location within enhancing areas, non-enhancing areas and necrotic areas on contrast enhanced T1-weighted MRI scans (cT1). MATERIALS AND METHODS: In 37 patients with newly diagnosed glioblastoma who underwent stereotactic biopsy, we obtained a correlation of 561 1mm3 biopsy specimens with their corresponding position on the intraoperative cT1 image at 1.5 Tesla. Biopsy points were categorized as enhancing (CE), non-enhancing (NE) or necrotic (NEC) on cT1 and tissue samples were categorized as "viable tumor cells", "blood" or "necrotic tissue (with or without cellular component)". Cell counting was done semi-automatically. RESULTS: NE had the highest content of tissue categorized as viable tumor cells (89% vs. 60% in CE and 30% NEC, respectively). Besides, the average cell density for NE (3764 ± 2893 cells/mm2) was comparable to CE (3506 ± 3116 cells/mm2), while NEC had a lower cell density with 2713 ± 3239 cells/mm2. If necrotic parts and bleeds were excluded, cell density in biopsies categorized as "viable tumor tissue" decreased from the center of the tumor (NEC, 5804 ± 3480 cells/mm2) to CE (4495 ± 3209 cells/mm2) and NE (4130 ± 2817 cells/mm2). DISCUSSION: The appearance of a glioblastoma on a cT1 image (circular enhancement, central necrosis, peritumoral edema) does not correspond to its diffuse histopathological composition. Cell density is elevated in both CE and NE parts. Hence, our study suggests that NE contains considerable amounts of infiltrative tumor with a high cellularity which might be considered in resection planning.