Em experimentos anteriores utilizando tarefa de tempo de reação (TR) vai/não-vai com diferentes estímulos-alvo aparecendo após um estímulo precedente, observamos efeito positivo do estímulo precedente quando o estímulo-alvo era uma linha dentro de um anel, mas não quando era uma cruz dentro de um anel. Este resultado foi atribuído a uma diferença nas discriminabilidades dos dois estímulos em relação ao estímulo negativo, um anel pequeno dentro do anel. A discriminação da cruz seria mais fácil, o que levaria os indivíduos a ignorar o estímulo precedente, resultando em ausência do efeito positivo. O objetivo deste trabalho foi comparar as discriminabilidades da linha e da cruz em relação ao estímulo negativo, o anel, para dar suporte à hipótese considerada, e a partir deste resultado discutir os processos responsáveis pela manifestação ou não de eventuais diferenças de discriminabilidade no comportamento. Nos experimentos 1, 2 e 3 utilizamos tarefas de tempo de reação vai/não-vai sem estímulo precedente, e nos experimentos 4 e 5 utilizamos tarefas com ênfase na acurácia das respostas. No primeiro experimento linha e cruz foram apresentadas em blocos de tentativas diferentes. Nestas condições, os TR à linha e à cruz se igualaram na segunda sessão, mas na primeira sessão o grupo que respondeu primeiro à linha e depois à cruz teve TR menores para a cruz. No segundo experimento, linha e cruz foram apresentadas aleatoriamente nos mesmos blocos de tentativas, para induzir a adoção de estratégia de resposta comum aos dois estímulos. Desta forma evidenciamos uma diferença nos TR, sendo que estes foram menores para a cruz, indicando que esta é mais discriminável que a linha. No terceiro experimento grupos diferentes de voluntários responderam à linha e à cruz. Os TR assim obtidos, iguais para linha e para cruz, indicam que as igualdades nos TR aos dois estímulos-alvo encontradas no primeiro experimento independem da exposição prévia a outro estímulo-alvo. O conjunto destes resultados sugere que linha e cruz têm discriminabilidades diferentes, sendo a cruz mais discriminável que a linha. Esta diferença, no entanto, é evidenciada apenas quando uma mesma estratégia de resposta é adotada para lidar com os dois estímulos. No quarto experimento construímos curvas psicométricas e observamos valores iguais de sensibilidade para a linha e para a cruz. No quinto experimento utilizamos uma tarefa de escolha. Uma análise por meio da Teoria de Detecção de Sinais forneceu medidas do parâmetro sensorial d´ maiores para a linha que para a cruz, indicando que a linha é mais discriminável que a cruz, além de medidas do parâmetro decisional critério iguais para os dois estímulos. Este padrão de resultados, contrário aos obtidos nos experimentos 1 a 3, foi atribuído às diferentes condições de estimulação com cada metodologia: em condições de estimulação supra-limiar como as utilizadas nas tarefas de TR a cruz é mais discriminável (em relação ao anel) que a linha, mas em condições de estimulação próximas do limiar a linha passa a ser mais discriminável. / In a former study in a go/no-go task, we found a reduction in reaction times (RT) at a cued position when the target stimulus was a line inside a ring but not when the target stimulus was a cross inside a ring. We hypothesized that this was due to a difference in the discriminabilities of the target stimuli from the no/go stimulus, a small ring inside a ring. The cross would be more easily discriminated from the no/go stimulus, causing the cue to lose its relevance and to be ignored. The goal of the present study was to compare the discriminabilities of the line and of the cross to support that hypothesis, and to determine the relative contributions of the attentional strategy and of the criterion to prevent such an existing difference from manifesting itself behaviorally. We ran three experiments with a go/no-go RT task with no cue and two experiments in which the accuracy of the responses was the dependent variable. In the first experiment the line and cross were presented in different blocks of trials. RT to both stimuli were equal in the second session of trials, but in the first session the group that responded first to the line (and later to the cross) had smaller RT to the cross. In the second experiment, line and cross were randomized in the same blocks of trials to force participants to respond to both stimuli with the same attentional strategy and/or criterion. This led to faster RT to the cross, indicating that it is easier to discriminate it than the line. In the third experiment the line and the cross were presented to different participants. This led to equal RT to both stimuli, indicating that the equality of RT found in Experiment 1 was not dependent on former experience with a different target stimulus. The results from these three experiments suggest that the cross is in fact easier to discriminate than the line, but this difference can only be expressed behaviorally if participants use the same attentional strategy and/or criterion to handle both stimuli. In the fourth experiment we used the accuracy data to build psychometric functions and we found no difference between responses to the line and to the cross on the slope of the curves or on the points of subjective equality. In the fifth experiment we used a Signal Detection Theory analysis to compare the sensitivity parameter d` and the bias parameter criterion and found bigger d` values to the line and no bias difference. These results are opposite to the RT results, probably because of differing stimulatory conditions. In high intensities such as the ones used in experiments 1, 2 and 3 the cross is more easily discriminated from the negative stimulus than the line, but in near-threshold intensities the line is more easily discriminated.

Atenção visual é a capacidade de processar melhor determinados estímulos em detrimento de outros. Tempos de Reação (TR) são medidas quantificáveis classicamente utilizadas para se estudar os efeitos atencionais a estímulos visuais. A atenção pode ser direcionada voluntariamente para outras regiões do espaço que não a determinada pelo ponto de fixação. Esse estudo teve por objetivo verificar o desenvolvimento da atenção visuoespacial em escolares por meio de medidas de TR em duas situações experimentais. Foram realizados dois experimentos psicofísicos em cinco grupos experimentais de acordo com suas faixas etárias (8, 9, 10, 12 e 15 anos de idade). O experimento I investigou a atenção explícita, que se caracteriza por ser a capacidade de alocar a atenção na região foveada. Já o experimento II estudou se a atenção visual poderia ser alocada em duas regiões não contíguas do espaço, caracterizando assim uma situação de atenção dividida. Como resultados observou-se que: (i) há diminuição dos TR em função da idade; (ii) na situação de atenção explícita, como esperado, todos os grupos foram capazes de alocar a atenção na região foveada.; (iii) na situação de atenção dividida, apenas o grupo de 15 anos foi capaz de apresentar divisão atencional. Esses resultados demonstram a viabilidade do método empregado no estudo da atenção em escolares e abre perspectivas de sua aplicação clínica em transtornos atencionais. / Visual attention is the ability to process certain stimuli in detriment of others. Reaction Times (RT) are the standard procedure to access the attentional effects on visual stimuli. Attention can be voluntary deployed to areas other than the gaze is. This study was aimed to investigate the development of visuo-spatial attention in school children through RT. Two experiments were employed and five groups, divided according to subjects age (8, 9, 10, 12 and 15 years old), were tested. Experiment I access overt attention whereas experiment II investigated a divided attention situation. Our findings showed: (i) there is a RT reduction as a function of age; (ii) all studied groups in the overt attention condition, as expected, were able to allocate attention where gaze was; (iii) only the 15 years old group was able to show divided attention in experiment II. These results showed the protocol\'s viability to access visual attention among children and open perspectives for its use in clinical settings such as attention disorders conditions.

Nos últimos vinte e cinco anos a atenção visual tem sido descrita em termos de diversas metáforas, salientando-se o holfote atencional, a lente zoom e o gradiente atencional. Um aspecto essencial dessas metáforas é a distribuição dos recursos atencionais no campo visual, que não é necessariamente determinado pelo ponto de fixação e que pode depender tanto de eventos externos como também de estados mentais. Esse estudo apresenta uma abordagem inovadora, baseada em tempos de reação analisados através de métodos geoestatísticos, para investigar como a atenção visual se distribui em áreas extensas do campo visual. Cinco diferentes experimentos foram realizados: no experimento I participantes foram solicitados a não atender nenhuma região em particular do espaço (da tela do computador) caracterizando assim a atenção difusa. Nos demais experimentos, os participantes foram solicitados a direcionar a atenção explicitamente ao centro (expt. II); de maneira encoberta para esquerda (expt. III) ou para direita (expt. IV); ou dividindo a atenção em duas regiões tanto a direita como a esquerda simultaneamente, mas não para o centro (expt. V). A distribuição espacial da atenção, medida através de tempos de reação, foi obtida na forma de mapa de pixieis resultante da análise geoestatísica. O experimento I teve como resultado um favorecimento atencional do quadrante nasal do hemicampo inferior. O experimento II, como esperado, apresentou um foco atencional coincidente com o ponto de fixação. Os experimentos III e IV mostraram claramente focos atencionais para esquerda e direita, respectivamente. Por fim o experimento V mostrou dois focos atencionais, à esquerda e direita, indicando divisão atencional. Esses resultados demonstram a utilidade da geoestatística para a análise de tempos de reação no estudo da atenção visual. O método também forneceu evidências claras da possibilidade de dividir a atenção visual à direita e à esquerda do ponto de fixação, um tema ainda controverso na literatura. / In the past twenty five years visual attention has been described in terms of varied metaphors, among which a spotlight, a zoom lens and a gradient field. An essential aspect of all these metaphors is the distribution of attentional resources in the visual field, which is not necessarily determined by the fixation point, and may depend on both external events and internal mental processes. This study presents a novel approach, based on reaction times and analyzing data with geostatistical techniques, to investigate how visual attention is allocated in large continuous regions of space. Five different experiments were performed: in experiment I participants were asked not to attend to any particular region, but rather try to spread their attention as uniformly as possible over the computer screen (diffuse attention). In the remaining experiments, participants were instructed to direct their visual attention overtly towards the center (expt. II), or covertly to the left (expt. III) to the right (expt. IV), or to divide their attention attending regions both right and left (but not to the center (expt. V). The spatial distribution of attention, as evaluated through reaction times, was obtained in the form of pixel maps resulting from the geostatistical analysis. Experiment I showed a lower hemifield advantage, in the nasal quadrant. Experiment II, as expected, presented an atentional focus coincident with the fixation point. Experiments IV and V showed clear attentional foci, to the left and to the right, respectively. Finally, Experiment V showed two clear lateral foci, one to the left, the other to the right, indicating attentional division. These results demonstrate the usefulness of geostatistics to analyze reaction time data for the study of visual attention. The method also provided clear evidence for the ability of subjects to divide their visual attention in two well separated foci, to the right and to the left of their fixation point, an issue still debated in the literature.

Doctorat en sciences psychologiques / info:eu-repo/semantics/nonPublished

Cocaine users display impaired inhibitory control. The influence of cocaine-related stimuli on inhibitory control has not been assessed. The Attentional Bias-Behavioral Activation (ABBA) task uses cocaine and neutral images as cues to determine if drug-related images impair inhibitory control in cocaine users. This dissertation was designed to assess the influence of cocaine images on inhibitory control in cocaine users through the conduct of studies designed to address four aims. The first aim was to demonstrate that cocaine users display impaired inhibitory control following cocaine images compared to neutral images on the ABBA task. This was accomplished through the conduct of two experiments. The first experiment piloted the ABBA task and cocaine users completed the cocaine go (n = 15) or neutral go condition (n = 15) of the task. The second experiment consisted of two studies designed to develop a within-subjects methodology for using the ABBA task. In the first study, cocaine users completed either the cocaine go (n = 20) or neutral go (n = 20) condition of the ABBA task and all participants also completed the Cued Go/No-Go task, with geometric shapes as cues. In the second study, cocaine users (n = 18) completed the cocaine go condition of the ABBA task and a modified version of the ABBA task with all neutral images as cues to further refine a possible within-subjects methodology. The second aim was to demonstrate that inhibitory failures occur most often when cues are presented for short compared to longer durations of time. Data collected during other protocols (n = 91) were combined to investigate the influence of stimulus onset asynchrony (SOA; i.e., the amount of time a cue is presented before a target indicated a response should be executed or withheld) on inhibitory control following cocaine-related and neutral cues on the ABBA task. The third aim was to demonstrate impaired inhibitory control following cocaine images on the ABBA task is specific to cocaine users. Cocaine users (data collected in the second experiment of the first aim) and non-using control participants (n = 16) completed the cocaine go and all neutral conditions of the ABBA task and the Cued Go/No-Go task. The fourth aim was to demonstrate the feasibility and acceptability of inhibitory control training to cocaine-related stimuli with cocaine users. A small pilot clinical trial was conducted and cocaine users were randomly assigned to complete inhibitory control training to cocaine images or geometric shapes. Cocaine images impaired inhibitory control on the ABBA task, as demonstrated by an increased proportion of inhibitory failures in the cocaine go condition compared to the neutral go condition in Experiments 1, 2, and 4. The proportion of inhibitory failures following cocaine images in Experiment 4 was increased at short (i.e., 100, 200) compared to long SOAs. Cocaine images also impaired inhibitory control compared to the Cued Go/No-Go Task in Experiment 2, however there were no differences in the proportion of inhibitory failures between the cocaine go and all neutral conditions of the ABBA task. There were no differences between cocaine users and controls in Experiment 3 for the proportion of inhibitory failures on the ABBA or Cued Go/No-Go tasks, but controls responded faster indicating a speed/accuracy trade off occurred in the control group. Inhibitory control training as an approach to improve treatment outcomes is feasible, as indicated by attendance and accuracy on the training task, and participants rated the overall procedure as satisfactory in Experiment 5. A better understanding of inhibitory control in the presence of cocaine related cues could be crucial to better understand how drug cues contribute to the risk for relapse and the continued use of drugs because both occur in the presence of drug cues.

Procedural learning abilities have been shown to be deficient in children who meet criteria for Developmental Dyslexia (DD) and those who meet criteria for Specific Language Impairment (SLI; Lum et al., 2010; Menghini et al., 2006). Further, grammatical understanding has been linked to implicit sequence learning abilities across SLI and typically developing children (Lum, 2012). The present study examined implicit sequence learning, measured by the Serial Reaction Time Task (SRTT), in children who met criteria for DD with or without SLI. Implicit sequence learning was modeled using multi-level growth models of initial reaction time and learning slope across the repeated sequences of the SRTT. We further examined the predictive contributions of grammatical understanding, vocabulary abilities, phonological awareness, and diagnostic groups on implicit learning performance on the SRTT. Results showed language abilities and diagnostic group did not relate strongly to rates of implicit learning.

The process of movement execution can be separated into two sections; the foreperiod and the response time. The foreperiod represents the time between the warning signal (WS) and the presentation of the imperative “go” signal, and the response time incorporates both the reaction time (RT) and the movement time (Schmidt & Lee, 2011). Transcranial magnetic stimulation (TMS) was used to probe corticospinal excitability (CE) which has been measured in a variety of RT tasks during both the foreperiod and the response time periods. The purpose of the two studies in this thesis was to measure when and at what rate changes in CE occur in both simple and complex tasks. The results of the first experiment indicated that CE levels quickly increased from baseline with the presentation of the WS. This was followed by a holding period in which CE was held constant until a decline in CE occurred prior to the presentation of the IS. This decline was followed by a rapid increase in CE as the movement was initiated and released. Importantly, even though levels of CE were decreasing relative to the start of the decline, participants were still in a heightened state as they prepared to release their movements. Furthermore, it is suggested that selective inhibitory control mechanisms were at least partly responsible for the decline prior to the IS. The results of the second experiment indicated that MEP amplitudes in a simple task were significantly larger compared to those in a complex task relative to both the IS and the onset of electromyography. These findings suggest that simple and complex tasks achieve differing levels of corticospinal excitability, and it is suggested that the complex requires the use of the cerebellum, which suppresses excitatory projections to the thalamus, and consequently to the motor cortex.

It is well established that aging is associated with numerous health concerns, including poor balance. Deteriorations in attention demand also place older adults at a greater risk for falls. Emerging experiments have explored the impact of dual-task training programs and have improved dual-tasking in older adults. However, it is unknown whether these performance-related improvements are a function of the intervention itself or the repeated exposure to the testing protocol. Study 1 explored the implications of repeated administration, once per week for 5 weeks, of a protocol involving standing postural sway while concurrently performing reaction time (RT) tasks in older adults. Results revealed that postural sway was stable across testing sessions whereas the difficult RT task gradually improved over time. Study 2 examined the influence of repeated exposure, once per week for 5 weeks, of a protocol involving negotiating a series of obstacles while performing RT tasks in older adults. Participants walked significantly faster with repeated exposure and gradually improved RT. Study 3 investigated the impact of repeated exposure, once per week for 5 weeks, to three functional mobility measures in older adults. It also examined the influence of a 12-week balance and mobility training (BMT) program as well as a 12-week balance and mobility plus cognitive training (BMT+C) program on functional mobility in older adults. Functional mobility served to be stable over time. Both the BMT and BMT+C groups significantly improved functional mobility and sustained these improvements at the 12-week follow-up, while no changes were observed in the control group. No differences between the BMT and BMT+C groups emerged. Experiment 4 examined the influence of BMT and BMT+C on postural sway and RT in older adults. Participants in both training groups significantly improved RT and sustained these improvements at the follow-up, while no changes were observed in the control group. No changes to postural control were shown in any group. No differences between the BMT and BMT+C groups emerged. Experiment 5 examined the influence of BMT and BMT+C on negotiating a series of obstacles while performing RT tasks in older adults. Both the BMT and BMT+C groups significantly improved RT and sustained these improvements at the follow-up, while no changes were observed in the control group. All groups showed faster time to completion of the obstacle series. No differences between the BMT and BMT+C groups emerged. Collectively, these findings suggest that BMT and BMT+C significantly improve functional mobility and divided attention, and sustain these improvements over time. Although some improvements were observed after repeated exposure over 5 weeks, no changes in the control group were observed. Therefore, the improvements exhibited from BMT and BMT+C are likely not a function of repeated exposure to the testing protocol, as participants may be more susceptible to performance-related improvements when the testing sessions are close in proximity. Altogether, these findings propose that, whether or not cognitive training is included, attention demanding dual-task training not only improves functional mobility and RT, but also sustains these improvements over time in older adults. These results may be used to improve the prescription of exercise in older adults.

No description available.

Background: E-sports is a grand industry and has been gaining momentum in the latest decades. Reaction time (RT) is an important part of most e-sports games and therefore a possible way to evaluate and improve RT is desired. A tool that evaluates the players and shows them what executive functions they should improve on through what physical activity would be a great way to evaluate and improve RT. There has been a lot of studies performed on the effects of physical fitness on RT. Most studies seem to agree that improved physical fitness results in improved RT.   Objectives: The aim of this thesis is to design an experiment that will evaluate the connection between e-sports players physical fitness, their RT and their executive functions through different tests. There will also be an evaluation of if it is possible to reliably find a connection between specific kinds of physical fitness and specific executive functions. The objectives are therefore to find suitable tests to evaluate RT and executive functions as well as finding a physical fitness test that allows for easy comparison between subjects.   Methods: Literature study is used to find the answers to the research questions through reading different studies and papers. Scopus was chosen as the database to find the different studies to read because of the vast amount of material available there.   Results: The test used to evaluate physical fitness will be the Army Physical Fitness Test (APFT). The tests that will evaluate RT and executive functions are the Stroop test, the Trail Making Test A & B, Tower of Hanoi and a variation of the n-Back test. It is very difficult to isolate executive functions and evaluate them without something else interfering with the results. This thesis’s hypothesis changed from the beginning of the research to that it was done. At first it was believed that executive functions could be isolated and evaluated separately, but that is no longer the case.   Conclusion: The experiment will most likely show that subjects with greater APFT score will achieve a better overall score on the RT tests than those with lower score. This experiment will most likely not work as a tool to evaluate the executive functions connection to specific physical exercises of e-sports players in the state that the experiment is currently envisioned. More studies are required to link specific physical exercises to specific executive functions before a tool can be created.