A música tem sido utilizada na pesquisa de percepção subjetiva de tempo por apresentar características de estrutura temporal, como o ritmo, o andamento, os acentos musicais, entre outros. A combinação destes elementos durante a escuta musical suscita a ativação de processos de atenção e memória envolvidos no processamento da percepção temporal. Face à diversidade de elementos que compõem a estrutura da música erudita ocidental, a utilização de uma análise multidimensional (MDS) tem contribuído para a pesquisa na área de cognição musical uma vez que delimita dimensões a partir de uma representação perceptual. A MDS provém de uma família de técnicas de análise de proximidade de dados, que é obtida por meio do julgamento do participante, que compara vários objetos (estímulos) em vários traços (elementos), concomitantemente. A utilização desta técnica visou identificar dimensões que influenciaram a percepção subjetiva de tempo durante uma tarefa de apreciação musical. 48 participantes (músicos e não músicos) ouviram 16 trechos musicais (20 segundos) do repertório erudito ocidental e os associaram às durações de 16, 18, 20, 22 e 24 segundos. Através da MDS foi gerada uma solução bidimensional representando a distribuição dos trechos musicais em função do julgamento de similaridade temporal. Uma análise musicológica foi realizada para avaliar os elementos musicais comuns encontrados nos trechos agrupados próximos. Foram identificados os elementos andamento, intensidade, densidade timbral e tensão, tanto para os músicos como para os não músicos. Foram identificadas duas dimensões complementares, 1) tensão e densidade timbral e 2) andamento e intensidade para os participantes músicos e 1) andamento e intensidade e 2) densidade timbral para os participantes não músicos, como responsáveis pela alteração na percepção subjetiva de tempo durante a apreciação de música erudita ocidental. / Music has been used in the research of subjective time perception because of its characteristics of temporal structure, as the rhythm, the tempo, the musical accents and others. The combination of these elements during musical listening task excite the activation of attention and memory processes involved in processing of the temporal perception. Due to the diversity of parameters which compose the structure of western erudite music, the use of a multidimensional scaling (MDS) contributed for the research in the musical cognition area once delimits dimensions from a perceptual representation The multidimensional scaling (MDS) comes from a family of analysis techniques of data proximity which is obtained by the participant judgment who compares some objects (stimuli) in some traces (elements), concomitantly. The use of this technique aimed at to identifying dimensions that influenced the subjective time perception during a musical appreciation task. 48 participants (musicians and non-musicians) were listen 16 musical excerpts (20 seconds) of the western erudite repertoire and associate them with the durations of 16, 18, 20, 22 and 24 seconds. Through the MDS a 2 dimensional solution was generated representing the distribution of the musical excerpts in function of the time similarity judgment. A musicology analysis was carried out to evaluate the common musical elements found in the grouped excerpts. It was identified the elements tempo, intensity, timbral density and tension, as much for the musicians as for non musicians. Two complementary dimensions had been identified, 1) tempo and intensity and 2) tension and timbral density for the participants musicians and 1) tempo and intensity and 2) timbral density for the participants non musicians, as responsible for the alteration in the subjective time perception during the appreciation of western erudite music.

Objetivo. Estudar mecanismos que limitam a precisão em tarefas de produção de ritmos e sincronização sensório-motora a partir da análise da variabilidade observada em tarefas de bater o dedo com tempo espontâneo, em sincronização sensório-motora a metrônomos externos, e ainda, na manutenção da ritmicidade definida por metrônomos externos, depois destes serem desligados. Método. Um total de 11 participantes (idade média de ± 23 anos, 5 homens, destros e sem formação musical) executaram tarefas de batida do dedo, com o vínculo de ser o mais regular possível, em 3 experimentos: batida de um ritmo espontâneo, sincronização a metrônomos externos (luminosos ou sonoros) com período de 200 ms, 400 ms e 800 ms, e da manutenção do ritmo definido pelos metrônomos, mesmo depois destes serem desligados. A análise dos dados privilegiou a análise dos desvios padrão e coeficientes de variação nos experimentos. Resultados. A periodicidade média espontânea escolhida pelos participantes foi 527,5 ms, com desvio padrão de 107 ms, correspondendo a uma frequência em torno de 2 Hz. O desvio padrão médio individual foi de aproximadamente 29 ms. A sincronização ao metrônomo luminoso foi significativamente mais imprecisa e variável do que ao metrônomo auditivo (p = 0.005). Essa diferença se manteve mesmo nas tarefas de continuação, batendo o dedo depois de desligar os metrônomos, tanto o luminoso quanto o sonoro. Surpreendentemente, a estabilidade das batidas na fase de continuação foi significativamente melhor do que na fase de sincronia, tanto com o metrônomo luminoso quanto com o sonoro (p < 0.004). Outro resultado importante foi que o coeficiente de variação (razão entre desvio padrão e período médio de batidas; aproximadamente 5%) manteve-se mais estável que o desvio padrão em todas as situações experimentais. Discussão. Os dados deste estudo confirmam dados na literatura que sugerem que a frequência espontânea dos movimentos periódicos de seres humanos seja tipicamente de 2 Hz, o que reforça a idéia que a escolha de um ritmo espontâneo seja baseada em substratos anatômicos (ressonâncias biomecânicas), relativamente invariantes entre indivíduos. Também foi confirmada a hipóteses sugeridas na literatura de que, a sincronia a estímulos sonoros é significativamente mais precisa e menos variável que a estímulos luminosos. A maior estabilidade na fase de continuidade do que na fase de sincronia com os estímulos guia, faz pensar que há interferências das pistas externas com o relógio interno. A estabilidade do coeficiente de variação, maior que a do desvio padrão, sugere que o relógio interno dependa de um mecanismo de acumulação. Conclusão. A faixa de 2 Hz presente em movimentos rítmicos oscilatórios é provavelmente inerente a substratos anatômicos relativamente invariantes. Metrônomos sonoros são mais eficientes em guiar a batida de dedo do que metrônomos luminosos. Não foi possível separar a contribuição do relógio interno à variabilidade das batidas de dedo, pois, surpreendentemente, na continuidade de batidas após desligamento de metrônomos externos, seja luminosos que sonoros, a estabilidade melhorou, em vez de piorar. A estabilidade do coeficiente de variação sugere o envolvimento direto de mecanismo de acumulação nos relógios internos, pelo menos nas escalas de tempo dos experimentos (200 a 800 ms). / Purpose: To study mechanisms that limit the accuracy of rhythm production and sensorimotor synchronization analyzing the variability in finger tapping tasks, be they spontaneous finger tapping, sensorimotor synchronization to external metronomes, or rhythm maintenance after turning off the external metronome. Methods: A total of 11 participants (mean age ± 23 years, 5 men, right handed and musically untrained) performed finger tapping tasks, with the constraint of highest possible regularity, in 3 experiments: spontaneous tapping, tapping in synchrony to external metronomes (light flashes or sound bips) with periods of 200 ms, 400 ms and 800 ms, and maintaining a steady pace set by the external metronome, after it was turned off. Data analysis focused on analysis of standard deviations and coefficients of variation. Results: The average frequency chosen by participants in spontaneous rhythm production was 527.5 ms with a standard deviation of 107 ms, corresponding to a frequency around 2 Hz. Average individual standard deviation was approximately 29 ms. Synchronization (and continuity) to the light metronome was significantly more imprecise and variable than synchronization to the sound metronome (p = 0.005). This difference persisted even in the continuation tasks, for both sound and light metronomes. Surprisingly, the stability in the continuation task was significantly better than during synchronization (p <0.004). Another important result was that the coefficient of variation (ratio of standard deviation to mean period; approximately 5%) was more stable than the standard deviation in all experimental conditions. Discussion: Data from this study confirm the literature, suggesting that the spontaneous frequency of periodic movements of humans is around 2 Hz, which reinforces the idea that they are based on anatomical substrates (biomechanical resonances), which are relatively invariant across individuals. Data from this study also confirmed literature reports that timing to sound metronomes is significantly more accurate and less variable than timing to light metronomes The greater stability in the continuation task than in synchronization task suggests that external cues interfere with the internal clock. The stability of the coefficient of variation, higher than the stability of the standard deviation suggests that the internal clock is based on accumulation mechanisms. Conclusion: The frequency of 2 Hz in the rhythmic oscillatory movements of humans is probably inherent to anatomical substrates that are relatively constant across individuals. Sound metronomes are more efficient in guiding finger tapping tasks than light metronomes. It was not possible to separate out the contribution of the internal clock to the variability of finger tapping, because stability was higher the continuation phase than in the synchronization phase, both with sound and with light metronomes. Finally, the stability of the coefficient of variation suggest the direct involvement of accumulation mechanisms in the internal clock, at least on the time scales of these experiments (200 to 800 ms).

A temporalidade compõe as ações do indivíduo no mundo, portanto, a subjetividade assume papel importante, pois a partir dela é que o tempo ganha sentido e significado. Assim, a percepção subjetiva do tempo torna-se fundamental para a concepção da realidade, traçando uma distinção entre o decurso temporal dos muitos eventos vivenciados ao longo da vida, o que implica que o processamento da informação temporal é imprescindível no cotidiano. Um campo de pesquisa que tem se dedicado a investigações sobre o tempo subjetivo é a Nova Estética Experimental, que estuda obras de arte ou outros fenômenos estéticos através de experimentos, nos quais atributos das obras são manipulados, visando verificar quais são seus efeitos sobre algum aspecto do comportamento do indivíduo. Nas artes, a artista plástica Lygia Clark considerava que a obra só teria significado na relação com o espectador através de sua manipulação; deste modo, ela cria a série Bichos, que são esculturas que modificam suas configurações em resposta à ação do espectador, isto é, podem ser exploradas manualmente. O tempo subjetivo se altera em função da densidade de movimento percebido. Uma obra de arte em que seu movimento é induzido por manipulação pode alterar o tempo subjetivo. Questiona-se qual seria a influência da atividade exploratória destas obras sobre a experiência temporal e como essa relação se daria em condições nas quais os participantes apresentassem alterações dos padrões motores, como os observados em pessoas com Doença de Parkinson (DP). Assim, a proposta deste trabalho foi examinar os efeitos da manipulação de uma obra de arte móvel sobre o tempo subjetivo em indivíduos que apresentam o diagnóstico de DP. No experimento 1, estudantes de pós-graduação julgaram modelos de obras de arte da série Bichos de Lygia Clark, para os atributos: Complexidade, Regularidade, Quantidade de Material, Interesse e Agradabilidade. Os julgamentos mostraram que os estímulos apontados com maior quantidade de material foram considerados com maior nível de complexidade e interesse, no entanto, com menor nível de agradabilidade; por outro lado, os estímulos avaliados com menor quantidade de material foram indicados com menor nível de complexidade e interesse, entretanto, com maior nível de agradabilidade. Este resultado foi importante para a determinação dos estímulos que foram utilizados no experimento 2. Participantes com diagnóstico de DP e participantes sem a doença manipularam duas reproduções, alteradas no número de faces, de obras da série Bichos de Lygia Clark e realizaram a estimação temporal verbal da duração de suas manipulações. O manuseio foi registrado sendo analisadas quatro categorias comportamentais: Tocar, Movimentar, Soltar e Deslocar o estímulo. A análise da atividade exploratória dos participantes revelou que os participantes com DP tocam e soltam mais os estímulos e os movimentam e deslocam menos em relação aos participantes sem a doença. As estimações temporais realizadas pelos participantes apontaram que a manipulação de uma obra de arte móvel altera a percepção subjetiva de tempo. Todos os participantes superestimaram o tempo de manipulação dos estímulos, no entanto, os indivíduos com DP apresentaram uma menor superestimação quando comparados aos participantes sem a doença. / The temporality makes up individuals actions in the world, therefore, subjectivity plays an important role, because time makes sense and meaning based on it. Thus, the subjective perception of time is fundamental to the conception of reality, drawing a distinction between the temporal course of the many events experienced throughout life, which implies that processing of temporal information is essential in daily life. A field of research that has been devoted to research on the subjective time is the New Experimental Aesthetics, studying works of art or other aesthetic phenomena through experiments in which some attributes of the works are handled in order to verify which are their effects on some aspects of individuals\' behavior. In the field of arts, the artist Lygia Clark considered that the work would only have meaning in relation to the spectator through their manipulation; thus she creates the \"Bichos\" series, which are sculptures that modify its settings in response to the action of the viewer, that is, can be operated manually. The subjective time changes depending on the density perceived movement. A work of art in which its movement is induced by manipulation can change subjective time. One wonders what would be the influence of the exploration activities of these works on the temporal experience and how this relationship would be in conditions in which participants present changes in their motor patterns, as seen in people with Parkinson\'s disease (PD). Thus, the purpose of this study was to examine the effects of the manipulation of a work of mobile art on subjective time in people who have a diagnosis of PD. In experiment 1, graduate students judged models of works of art from the series \"Bichos\" by Lygia Clark, for rating the following attributes: Complexity, Regularity, Material Amount, Interest and Agreeableness. Trials showed that the stimuli that indicated larger amount of material were considered with a higher level of complexity and interest, however, with lower level of agreeableness; On the other hand, the stimuli evaluated as having less material were also indicated with lower complexity and interest, however, with higher levels of agreeableness. This result was important to determine the stimuli that were used in experiment 2. Participants diagnosed with PD and participants without the disease manipulated two reproductions of some works from the series \"Bichos\" by Lygia Clark with the number of faces altered, and performed a verbal estimation of the temporal duration of their manipulations. The handling was recorded and four behavioral categories were analyzed: Touch, Move, Displace works position, and Drop the piece of art (stimulus). The analysis of the exploratory activity of the participants showed that those with PD touched and dropped more the stimulus, and, in contrast, they moved and displaced it less than the participants without the disease. The time estimates made by the participants pointed out that handling the work of mobile art altered the subjective perception of time. All participants overestimated the handling time of the stimuli, however, subjects with PD showed a lesser overestimation than participants without the disease.

Estudos sugerem mudanças na percepção do tempo subjetivo com o envelhecimento, sendo comum a afirmação de que o tempo passa mais rapidamente com o aumento da idade. Alguns dos fatores estudados que afetam o tempo subjetivo são as emoções e o valor hedônico associado a estímulos musicais. Este estudo verificou se aspectos emocionais relacionados a diferentes estímulos musicais interferem na percepção subjetiva do tempo em diferentes fases da velhice. 54 pessoas de 50 até 90 anos de idade participaram do estudo. Foram apresentados quatro estímulos musicais para os diferentes grupos de idade e o tempo foi estimado pelo participante segundo o paradigma prospectivo, através da reprodução temporal. Os resultados mostraram que houve diferença nos tempos reproduzidos entre as categorias emocionais Alegria e Tristeza. Os estímulos Alegres foram percebidos como mais longos que os Tristes para todos os participantes. Foram encontradas diferenças significativas entre o grupo abaixo de 60 anos e o grupo acima de 80 anos, com reproduções mais curtas para o grupo abaixo de 60 anos. A música Triste apresentou correlação positiva significativa entre o tempo subjetivo e idade, com tempo subjetivo mais longo com o aumento da idade. De modo geral, foi verificado que todos os participantes subestimaram o tempo, e uma tendência a um aumento do tempo reproduzido em relação ao aumento da idade, se aproximando mais do valor real de duração do estímulo musical / Studies suggest changes on the perception of subjective time with aging, being ordinary the statement that says \"time goes by faster\" with the increasing of age. Some of the factors that affect subjective time are the emotions and the hedonic value associated to musical stimulus. This study verified if emotional aspects related to different musical stimulus interfere on the subjective perception of time on different stages of old age. 54 people between 50 and 90 years old participated on the study. Four musical stimuli were presented to different age groups and time was estimated by the participant according to the prospective paradigm, through temporal reproduction. The results showed that there was a difference on reproduced times between the emotional categories Happiness and Sadness. Happy stimuli were longer than the Sad ones for all participants. Significant differences were found between the group under 60 years old and the group older than 80 years old, with shorter reproduction found in the group under 60 years old. Sad music presented meaningful positive correlation between subjective time and age, with longer subjective time with aging. Generally, it was verified that all participants underestimated time, along with a tendency to increase reproduced time related with aging, getting closer to the real value of the duration of musical stimulus

Action has many influences on how and what we perceive. One robust example of the relationship between action and subsequent perception, which has recently received great attention in the cognitive sciences, is the “intentional binding” effect: When people estimate the timing of their actions and those actions’ effects, they judge the actions and effects as having occurred closer together in time than two events that do not involve voluntary action (Haggard, Clark, & Kalogeras, 2002). This dissertation examines the possible mechanisms and consequences of the intentional binding effect. First, in Chapter 1, I discuss previous literature on the relationships between experiences of time, action, and causality. Impressions of time and causality are psychologically related: The perceived timing of events impacts, and is impacted by, perceived causality. Similarly, one’s experience of causing and controlling events with voluntary action, sometimes called the sense of agency, shapes and is shaped by how those events’ timing is perceived—as shown by the intentional binding effect. In Chapter 2 I present a series of experiments investigating a hypothesized mechanism underlying the intentional binding effect: Actions may lead to a slowing of subjective time, which would explain the intentional binding effect by postulating a shorter experienced duration between action and effect. This hypothesis predicts that, following action, durations separating any two stimuli would appear subjectively shorter. We tested this hypothesis in the context of visual motion illusions: Two visual stimuli are presented in short succession and if the duration between the stimuli (inter-stimulus interval; ISI) is short, participants tend to perceive motion such that the first stimulus appears to move to the position of the second stimulus. If actions shorten subjective durations, even in visual perception, people should observe motion at longer ISIs when the stimuli follow voluntary action because the two stimuli would be separated by less subjective time. Three experiments confirmed this prediction. An additional experiment showed that verbal estimates of the ISI are also shorter following action. A control experiment suggested that a shift in the ability to prepare for the stimuli, afforded by the participant initiating the stimuli, is an unlikely alternative explanation of the observed results. In Chapter 3 I further investigate whether temporal contiguity of actions and their effects, which is known to impact intentional binding, affects perceptions of visual motion illusions. Two experiments showed that temporal contiguity modulates perceptions of illusory motion in a manner similar to contiguity’s effect on intentional binding. Together, these results show that actions impact perception of visual motion illusions and suggest that general slowing of subjective time is a plausible mechanism underlying the intentional binding effect.

This thesis documents a series of experiments designed to investigate the mechanisms subserving sub-second duration processing in humans. Firstly, duration aftereffects were generated by adapting to consistent duration information. If duration aftereffects represent encoding by neurons selective for both stimulus duration and non-temporal stimulus features, adapt-test changes in these features should prevent duration aftereffect generation. Stimulus characteristics were chosen which selectively target differing stages of the visual processing hierarchy. The duration aftereffect showed robust interocular transfer and could be generated using a stimulus whose duration was defined by stimuli invisible to monocular mechanisms, ruling out a pre-cortical locus. The aftereffects transferred across luminance-defined visual orientation and facial identity. Conversely, the duration encoding mechanism was selective for changes in the contrast-defined envelope size of a Gabor and showed broad spatial selectivity which scaled proportionally with adapting stimulus size. These findings are consistent with a second stage visual spatial mechanism that pools input across proportionally smaller, spatially abutting filters. A final series of experiments investigated the pattern of interaction between concurrently presented cross-modal durations. When duration discrepancies were small, multisensory judgements were biased towards the modality with higher precision. However, when duration discrepancies were large, perceived duration was compressed by both longer and shorter durations from the opposite modality, irrespective of unimodal temporal reliability. Taken together, these experiments provide support for a duration encoding mechanism that is tied to mid-level visual spatial processing. Following this localised encoding, supramodal mechanisms then dictate the combination of duration information across the senses.

The past twenty years have seen a successful formalization of the idea that perception is a form of probabilistic inference. Bayesian Decision Theory (BDT) provides a neat mathematical framework for describing how an ideal observer and actor should interpret incoming sensory stimuli and act in the face of uncertainty. The predictions of BDT, however, crucially depend on the observer’s internal models, represented in the Bayesian framework by priors, likelihoods, and the loss function. Arguably, only in the simplest scenarios (e.g., with a few Gaussian variables) we can expect a real observer’s internal representations to perfectly match the true statistics of the task at hand, and to conform to exact Bayesian computations, but how humans systematically deviate from BDT in more complex cases is yet to be understood. In this thesis we theoretically and experimentally investigate how people represent and perform probabilistic inference with complex (beyond Gaussian) one-dimensional distributions of stimuli in the context of sensorimotor decision making. The goal is to reconstruct the observers’ internal representations and details of their decision-making process from the behavioural data – by employing Bayesian inference to uncover properties of a system, the ideal observer, that is believed to perform Bayesian inference itself. This “inverse problem” is not unique: in principle, distinct Bayesian observer models can produce very similar behaviours. We circumvented this issue by means of experimental constraints and independent validation of the results. To understand how people represent complex distributions of stimuli in the specific domain of time perception, we conducted a series of psychophysical experiments where participants were asked to reproduce the time interval between a mouse click and a flash, drawn from a session-dependent distribution of intervals. We found that participants could learn smooth approximations of the non-Gaussian experimental distributions, but seemed to have trouble with learning some complex statistical features such as bimodality. To investigate whether this difficulty arose from learning complex distributions or computing with them, we conducted a target estimation experiment in which “priors” where explicitly displayed on screen and therefore did not need to be learnt. Lack of difference in performance between the Gaussian and bimodal conditions in this task suggests that acquiring a bimodal prior, rather than computing with it, is the major difficulty. Model comparison on a large number of Bayesian observer models, representing different assumptions about the noise sources and details of the decision process, revealed a further source of variability in decision making that was modelled as a “stochastic posterior”. Finally, prompted by a secondary finding of the previous experiment, we tested the effect of decision uncertainty on the capacity of the participants to correct for added perturbations in the visual feedback in a centre of mass estimation task. Participants almost completely compensated for the injected error in low uncertainty trials, but only partially so in the high uncertainty ones, even when allowed sufficient time to adjust their response. Surprisingly, though, their overall performance was not significantly affected. This finding is consistent with the behaviour of a Bayesian observer with an additional term in the loss function that represents “effort” – a component of optimal control usually thought to be negligible in sensorimotor estimation tasks. Together, these studies provide new insight into the capacity and limitations people have in learning and performing probabilistic inference with distributions beyond Gaussian. This work also introduces several tools and techniques that can help in the systematic exploration of suboptimal behaviour. Developing a language to describe suboptimality, mismatching representations and approximate inference, as opposed to optimality and exact inference, is a fundamental step to link behavioural studies to actual neural computations.

Patients' non-adherence to treatment is a widespread phenomenon in healthcare. Time preferences (how individuals value outcomes over time) are one cause for non-adherence. Using quasi-hyperbolic discounting, two options in the future are weighted consistently. However, when the early option becomes available the weighting changes. This creates the potential for non-adherence. The agency relationship that exists between patients and doctors implies hidden information. When the patient's time preferences are hidden from the doctor, the doctor must choose how to recommend treatments. Exploring how doctors make treatment decisions when time preferences are hidden from them, and how this impacts adherence, is therefore important. The first contribution of the thesis is to outline a model of the patient-doctor interaction incorporating quasi-hyperbolic discounting and hidden information. This shows that doctors should adapt to non-adherence when the probability a patient is present-biased is large enough. Secondly, a national survey of Scottish GPs explores whether doctors have different time preferences for themselves or their patients. Doctors do have the same private and professional time preferences, but value the health state differently between frames. Lastly, a laboratory experiment tests whether students in the role of a doctor adapt to non-adherence in the way predicted by the model. Students find the socially optimal level of treatment on average. Adaptation is stronger when using a performance payment, and results did not vary along demographic characteristics. The thesis highlights the importance of the patient-doctor interaction for generating nonadherence, not just patient preferences. It also shows that GPs' private time preferences may suitably substitute their preferences for patients. Finally, it points towards potential incentives for doctors to improve patient outcomes.

M. Arch.

The present study aimed to evaluate (a) the extent to which different impulsivity measures would be related to each other and to a risk taking measure, (b) the extent to which impulsivity, risk taking, time perception and time perspective are related to each other, and (c) the extent to which these processes differ in Latino and White American students. Experiment I was conducted at Utah State University. One hundred and fortythree participants were exposed to the delay discounting, probability discounting and temporal bisection procedures, and answered the Barratt Impulsiveness Scale (BIS-11) and the Zimbardo Time Perspective Inventory (ZTPI). Results showed that (a) the AUC for delay discounting was related to the scores on the BIS-11 scale, (b) the AUCs for delay and probability discounting were positively and significantly correlated, (c) the mean of the temporal bisection procedure was correlated with the AUC of the delaydiscounting procedure, (d) the scores on the ZTPI were correlated with the impulsivity measures, and (e) the scores on the ZTPI subscales were also correlated with the risk taking measure. These results suggest that different impulsivity measures may be evaluating similar decision-making processes, that impulsivity and risk taking may be different decision- making processes, and that time perception and time perspective are related to impulsivity and risk taking. Experiment II was conducted at Washington University in St. Louis, with 18 Latinos and 16 White Americans. Results show that while Latinos were more impulsive in the delay discounting procedure, their scores did not differ from the White Americans on the BIS-11. Interestingly, Latinos and White Americans did not differ on time perception, but they did differ on time perspective: Latinos scored higher on fatalism compared to White Americans.