Submitted by Fabíola Silva (fabiola.silva@famerp.br) on 2016-10-03T18:10:48Z No. of bitstreams: 1 karinadeoliveirayounan_dissert.pdf: 994368 bytes, checksum: d0380b444a2b69e0b3248499e6a74c26 (MD5) / Made available in DSpace on 2016-10-03T18:10:48Z (GMT). No. of bitstreams: 1 karinadeoliveirayounan_dissert.pdf: 994368 bytes, checksum: d0380b444a2b69e0b3248499e6a74c26 (MD5) Previous issue date: 2014-08-22 / Introduction: The parasite Toxoplasma gondii infects a high percentage of individuals worldwide and disturbances resulting from this infection contribute to the aggravations of health conditions and may affect the intellectual development of children and adults. It has been suggested that the D antigen (Rh0) a glycoprotein that is the biochemical basis Rh but is absent in the nervous tissue, influence the motor response in the presence of T. gondii infection. Objectives: This study aims to evaluate the motor response and the reaction time for visual stimulus in the presence and in the absence of infection by the parasite T. gondii in individuals with good visual acuity, Rh positive and Rh negative. Methods: 212 volunteers from both sexes underwent visual acuity testing and measurement of average response time to visual stimulus (ART) by using a specific software. The collected blood samples were used to identify the erythrocyte RH phenotypes (positive and negative) and antibodies of IgG class anti-T. gondii (presence or absence). Average response times were compared according to sex, presence (reagents) and absence (non-reagent) infection and erythrocyte Rh phenotypes (positive and negative). The t test for comparison of average and the values of Odds Ratio (OR) and 95% confidence interval were calculated using the GraphPad Instat (version 6.3) software. The p-value equal to or less than 0.05 was considered significant. Results: The differences between the average age of reagents individuals (n = 134) and non-reagent (n = 38) to T. gondii were considered statistically significant (54.1 ± 18.7 vs 34.4 ± 18.9; p = 0.0001). The Rh phenotype positive (n = 189) was present in 89% of individuals, while the Rh-negative (n = 23) in 11%. The ART of reagents individuals for T. gondii was lower in males (0.672 ± 0.303) than in females (0.819 ± 0.270) (p = 0.0036). This same difference was observed between the non-reagent (0.475 ± 0.140 vs 0.791 ± 0.323), respectively (p <0.0001). Infected men (0.658 ± 0.282) had higher ART xi than uninfected men (0.488 ± 0.129) for T. gondii, both Rh positive (p = 0.0004). Women, infected or not, did not differ for ART even when compared by phenotype (positive or negative) Rh. Conclusions: Rh positive men infected with T. gondii have a higher ART than uninfected Rh positive men. Infected women do not differ in ART compared to women uninfected by T. gondii. / Introdução: O parasito Toxoplasma gondii infecta elevado percentual de indivíduos em todo o mundo e os distúrbios resultantes da infecção contribuem para os agravos da saúde e podem acometer o desenvolvimento intelectual de crianças e adultos. Tem sido proposto que o antígeno D (Rh0), uma glicoproteína que constitui a base bioquímica sistema Rh mas que se encontra ausente no tecido nervoso, influencia a resposta motora na presença de infecção por T. gondii. Objetivos: O objetivo deste estudo foi avaliar a resposta motora e o tempo de reação a estímulos visuais na presença e na ausência de infecção pelo parasito T.gondii em indivíduos com boa acuidade visual, Rh positivos e Rh negativos. Métodos: foram analisados 212 indivíduos voluntários, de ambos os sexos, submetidos a exame de acuidade visual e teste de medição de tempo médio de reação a estímulos visuais (TMR) com o uso de um software específico. As amostras de sangue coletadas foram utilizadas na identificação dos fenótipos eritrocitários Rh (positivo e negativo) e dos anticorpos da classe IgG, anti-T. gondii (presença ou ausência). Os tempos médios de reação foram comparados de acordo com o sexo, presença (reagentes) e ausência (não reagentes) de infecção e fenótipos eritrocitários Rh (positivo e negativo). O teste t para comparação das médias e os valores de Odds Ratio (OR) e do intervalo de confiança a 95% foram calculados com o uso do software GraphPad Instat (versão 3.06). O valor p igual ou menor que 0,05 foi considerado significante. Resultados: As diferenças entre as médias de idade de indivíduos reagentes (n=134) e não reagentes (n=78) ao T. gondii foram consideradas estatisticamente significante (54,1 ± 18,7 vs 34,4 ± 18,9; p=0,0001). O fenótipo Rh positivo (n=189) esteve presente em 89% dos indivíduos, enquanto o Rh negativo (n=23) em 11%. O TMR dos indivíduos reagentes para o T. gondii foi menor no sexo masculino (0.672 ± 0.303) que no feminino (0.819 ± 0.270) (p=0,0036). Esta mesma diferença foi observada entre os não reagentes (0.475 ± 0.140 vs 0.791 ± 0.323), respectivamente (p<0,0001). Homens infectados (0.658 ± 0.282) apresentam TMR maiores que homens não infectados (0.488 ± 0.129) por T. gondii, ambos Rh positivo (p=0,0004). Mulheres, infectadas ou não, não diferiram quanto ao TMR mesmo quando comparadas pelo fenótipo Rh (positivo ou negativo). Conclusões: Homens Rh positivos infectados por T. gondii apresentam TMR maior que homens Rh positivos não infectados. Mulheres infectadas não diferem quanto ao TMR em comparação a mulheres não infectadas por T. gondii.

Investigamos, no Experimento, se o estímulo precedente, que captura a atenção quando existem demarcações, deixa de capturar a atenção na ausência de demarcações por ter seu processamento filtrado precocemente. Além disso, investigamos, nos experimentos 2, 3 e 4, se alterações no fundo da tela, que gerassem maior competição no processamento dos estímulos presentes na cena visual, poderiam levar à captura da atenção, mesmo sem a presença das demarcações classicamente utilizadas. Observamos que quando a intensidade dos estímulos competidores presentes na tela era alta, o estímulo precedente passou a capturar a atenção. Explicamos esse resultado com a hipótese de que as demarcações são importantes por adicionarem ruído ao processamento dos estímulos apresentados, influenciando a representação desses estímulos e, portanto, a possibilidade de um estímulo capturar a atenção. Por fim, no Experimento 5, investigamos se os resultados da tarefa de escolha de local seriam replicados em uma tarefa de discriminação de forma. / In Experiment 1 we investigated if a peripheral stimulus, which is able to capture attention when there are placeholders on the screen, is no longer able to capture attention in the absence of placeholders because is early filtered. In Experimento 2, 3 and 4 we investigated if changes on screen background, which would generate stronger processing competition between stimuli, could lead to attentional capture even in absence of placeholders. Accorging to our results the peripheral stimuli is able to capture attention when competing stimuli of high intensity are presented togueter on screen. Our explanation is that placeholders are important because they add noise to stimuli processing, affecting stimuli representation and, therefore, the probability that a stimulus will capture attention. Lastly, in Experimento 5 we investigated if similar results would be obtained in a form discrimination task.

The ability of the brain to change and form new neuropathways after brain injury is remarkable. The current study investigates the brains ability to form new pathways for language processing following traumatic brain injury (TBI), specifically a left temporal lobectomy. Two subjects participated in this study; one participant with TBI and one age-matched control. Sentence stimuli consisted of four types: semantically correct, semantically incorrect, syntactically correct, and syntactically incorrect. Participants underwent a fMRI scan while the auditory stimuli were presented in four blocks. Participants were asked to record if the sentence was correct or incorrect by pressing the corresponding button. It was found that reaction times for both the participant with TBI and the control were longer for the incorrect conditions. The participant with TBI generally had longer reaction times compared to the control participant and had more errors. During the fMRI scans, patient movement occurred. The block design was not set up to account for movement. Due to this factor, imaging results are questionable. While there were differences between the participant with TBI and the control participant, these differences are expected to be much larger in someone with this degree of brain injury. It is recommended for further studies to be conducted in this area with a revised block design to account for patient movement.

<p>Bilder av potentiella hot upptäcks snabbt och leder till en snabbare reaktionstid än bilder av icke-potentiella hot. Potentiella hot stjäl också fokus och kognitiva resurser, med en långsammare reaktionstid som följd. Rädsla, som kan mätas genom startlereflexen, leder till antingen ökad handlingsberedskap (snabbare reaktionstid) eller kognitiv distraktion (långsammare reaktionstid). Fem försöksdeltagare fick reagera på en visuell probe som lades ovanpå djurbilder, både potentiella hot och icke-potentiella hot i ett kombinerat reaktionstids- och startleprobeexperiment, där ljudstötar utdelades i hörlurar. Startlereaktion, hjärtfrekvens och reaktionstid mättes, varefter korrelationskoefficienter räknades ut. Resultatet visade på en svag negativ korrelation mellan reaktionstid och startlepotentiering på gruppnivå, men inga signifikanta samband påvisades på individnivå. Resultatet på gruppnivå kan bero på att de individuella resultaten tenderar samlas i kluster och därför skapar ett skensamband. Även en positiv korrelation mellan hjärtfrekvensförändring och startlereaktion påvisades, men ingen korrelation mellan hjärtfrekvens och reaktionstid.</p> / <p>Pictures of fear relevant animals are detected fast and lead to shorter reaction time, compared to pictures of fear irrelevant animals. Fear relevant animals also capture attention and steals focus, which leads to slower reaction time. Fear leads to either preparedness for action (faster reaction time) or cognitive distraction (slower reaction time). In a combined startle probe and reaction time experiment, five participants were requested to react to a visual probe, superimposed on pictures of animals, both relevant and irrelevant to fear. Startle probes were given as noise bursts in headphones. Startle reaction, heart rate and reaction time were measured. A negative correlation between reaction time and startle potentiation was found on group level, whereas no significant correlations were found on the individual level. However, the individual results tend to gather in clusters, which might give a significant result on group level even if there is none.</p>

Bilder av potentiella hot upptäcks snabbt och leder till en snabbare reaktionstid än bilder av icke-potentiella hot. Potentiella hot stjäl också fokus och kognitiva resurser, med en långsammare reaktionstid som följd. Rädsla, som kan mätas genom startlereflexen, leder till antingen ökad handlingsberedskap (snabbare reaktionstid) eller kognitiv distraktion (långsammare reaktionstid). Fem försöksdeltagare fick reagera på en visuell probe som lades ovanpå djurbilder, både potentiella hot och icke-potentiella hot i ett kombinerat reaktionstids- och startleprobeexperiment, där ljudstötar utdelades i hörlurar. Startlereaktion, hjärtfrekvens och reaktionstid mättes, varefter korrelationskoefficienter räknades ut. Resultatet visade på en svag negativ korrelation mellan reaktionstid och startlepotentiering på gruppnivå, men inga signifikanta samband påvisades på individnivå. Resultatet på gruppnivå kan bero på att de individuella resultaten tenderar samlas i kluster och därför skapar ett skensamband. Även en positiv korrelation mellan hjärtfrekvensförändring och startlereaktion påvisades, men ingen korrelation mellan hjärtfrekvens och reaktionstid. / Pictures of fear relevant animals are detected fast and lead to shorter reaction time, compared to pictures of fear irrelevant animals. Fear relevant animals also capture attention and steals focus, which leads to slower reaction time. Fear leads to either preparedness for action (faster reaction time) or cognitive distraction (slower reaction time). In a combined startle probe and reaction time experiment, five participants were requested to react to a visual probe, superimposed on pictures of animals, both relevant and irrelevant to fear. Startle probes were given as noise bursts in headphones. Startle reaction, heart rate and reaction time were measured. A negative correlation between reaction time and startle potentiation was found on group level, whereas no significant correlations were found on the individual level. However, the individual results tend to gather in clusters, which might give a significant result on group level even if there is none.

Tyrimo tikslas – įvertinti ligonių, po galvos smegenų insulto, pažeistos rankos funkciją bei reakcijos laiką reabilitacijos eigoje.Tyrimo uždaviniai: 1) įvertinti ligonių, po galvos smegenų insulto pažeistos rankos plaštakos jėgą dinamometru reabilitacijos eigoje; 2) įvertinti ligonių, po galvos smegenų insulto pažeistos rankos funkciją per duotą laiką pagal Frenchay rankos testą reabilitacijos eigoje; 3) įvertinti ligonių, po galvos smegenų insulto pažeistos rankos reakcijos laiką taikant „Liniuotės“ testą reabilitacijos eigoje; 4) nustatyti veiksnius, įtakojančius ligonių, po galvos smegenų insulto pažeistos rankos funkciją bei reakcijos laiką reabilitacijos eigoje.Tyrimo metodika: tyrimas buvo atliekamas Abromiškių reabilitacijos ligoninės neurologijos skyriuje 2009 – 2010 m. Tyrime dalyvavo 21 moteris ir 21 vyras. Tiriamųjų amžiaus vidurkis buvo 63,3 ± 11,8 m. Bendradarbiaujant su reabilitacijos ligoninėje dirbančiais psichologais ir pritaikius atrankos priemonę, trumpą protinės būklės tyrimą (TPBT), tyrimui buvo atrinkti tiriamieji, kurių TPBT buvo ne mažiau kaip 20 balų, nes tolimesniam tyrimui reikėjo, kad ligoniai suprastų komandas ir jas vykdytų. JAMAR® hidrauliniu rankos dinamometru buvo vertinta ligonių rankų raumenų jėga. Frenchay rankos testu buvo vertintas rankos ir plaštakos su pareze miklumas. Ligonių pažeistos rankos reakcijos laiką vertinome „Liniuotės“ testu. Matavimai buvo atliekami 2 kartus: prieš ir po reabilitacijos.Tyrimo išvados: 1) reabilitacijos... [toliau žr. visą tekstą] / The aim of the research - to evaluate the function and reaction speed of the affected hand of the patient after stroke during the rehabilitation.The tasks of the research: 1) to evaluate the strength of the stroke affected hand using dynamometer during the rehabilitation; 2) to evaluate the function of the stroke affected hand in given time using Frenchay arm test during the rehabilitation; 3) to evaluate the reaction time of the stroke affected hand using “Ruler” test during the rehabilitation; 4) to determine the factors that influence the function and reaction of the stroke affected hand during the rehabilitation. Research methodology: the research was executed in Abromiškės rehabilitation clinic, neurology department in 2009 – 2010. 21 men and 21 women participated in it. The average age of the examined people was 63,3 ± 11,8 years. With the help of the psychologists of the clinic and selection method of Mini Mental State Examination (MMSE) patients were selected for the research with MMSE no less than 20 points because it was essential for the patients to understand and follow the commands. The strength of the arm muscles was measured with JAMAR® hydraulic hand dynamometer. The dexterity of the arm and palm with paresis was evaluated by Frenchay arm test. The affected hand reaction time was evaluated by “Ruler” test. The tests were performed twice: before and after rehabilitation.Research conclusions: 1) at the beginning of the rehabilitation the average strength of... [to full text]

In open skill sports and other tasks, decision-making can be as important as physical performance. Whereas many studies have investigated visual perception there is little research on auditory perception as one aspect of decision making. Auditory localisation studies have almost exclusively focussed on underlying processes, such as interaural time difference and interaural level difference. It is not known, however, whether semantic spatial information contained in the sound is actually used, and whether it assists pure auditory localisation. The aim of this study was to investigate the effect on auditory localisation of spatial semantic information. In Experiment One, this was explored by measuring whole body orientation to the words &quotLeft", &quotRight", &quotBack", &quotFront" and &quotYes", as well as a tone, each presented from left right, front and back locations. Experiment Two explored the effect of the four spatial semantic words presented either from their matching locations, or from a position rotated 20 degrees anticlockwise. In both experiments there were two conditions, with subjects required to face the position indicated by the sound location, or the meaning of the word. Movements of the head were recorded in three dimensions with a Polhemus Fastrak system, and were analysed with a custom program. Ten young adult volunteers participated in each experiment. Reaction time, movement time, initial rotation direction, rotation direction at peak velocity, and the accuracy of the final position were the dependent measures. The results confirmed previous reports of confusions between front and back locations, that is, errors about the interaural axis. Unlike previous studies, many more back-to-front than front-toback errors was made. The experiments provided some evidence for a spatial Stroop interference effect, that is, an effect on performance of conflicting information provided by the irrelevant dimension of the stimulus, but only for reaction time and initial movement direction, and only in the Word condition. The results are interpreted using a model of the processes needed to respond to the stimulus and produce an orienting movement. They suggest that there is an asymmetric interference effect in which auditory localisation can interfere with localisation based on semantic content of words, but not the reverse. In addition, final accuracy was unaffected by any interference, suggesting that these effects are restricted to the initial stages of response selection.

O tempo resposta é um indicador usado para avaliação da qualidade de serviços de atendimento pré-hospitalar (APH). Consiste no intervalo de tempo entre a expressão do pedido de socorro até a chegada da equipe à cena do evento. Assim, o objetivo do estudo foi analisar o tempo resposta de um SAMU, referente aos chamados para atendimentos clínicos e traumáticos demandados à Central de Regulação de Urgências. Os agravos clínicos foram compostos pelas síndromes neurológicas, cardiovasculares e respiratórias, por serem considerados agravos tempo dependentes; os agravos traumáticos foram constituídos pelos acidentes de trânsito e quedas, por serem os mais prevalentes no serviço. Trata-se de um estudo transversal retrospectivo. A amostra foi constituída por 1.580 atendimentos realizados em 2013, sendo 793 atendimentos clínicos e 787 atendimentos traumáticos. Os dados foram extraídos do sistema informatizado da central de regulação do SAMU de Porto Alegre (SAPH True), transpostos para o programa Microsoft Excel e analisados através do Programa Statistical Package for the Social Sciences (SPSS), versão 21.0. Os resultados evidenciam que o tempo resposta total foi de mediana de 19 minutos e os fatores que permaneceram associados estatisticamente com maior tempo de resposta total, após o ajuste pelo modelo multivariado, foram: tipo de socorro clínico (p<0,001), turno da noite (p<0,001), equipe básica (p=0,016), dias úteis da semana (p<0,001) e ocorrência de incidente no local do chamado (p=0,001). Em relação à faixa etária e gravidade presumida, não há diferenças significativas de tempo resposta. O tempo resposta total, formado pelas parcelas de tempo de cada etapa do atendimento, é influenciado pelo desempenho dos profissionais na comunicação e na avaliação das demandas do usuário e pelo tempo de mobilização da equipe para a partida para os atendimentos. O tempo resposta poderá ser reduzido através de processos de educação permanente com os profissionais do serviço para discussão e reorganização de práticas e com medidas de planejamento na organização estrutural do SAMU. / Response time (RT) is an indicator used to assess the quality of prehospital emergency care (PHEC). It is defined as the interval of time between a call for help and the arrival of the response team at the scene of the incident. In light of this, the objective of this study was to analyze the response time of the Brazilian Mobile Emergency Service (SAMU) to calls regarding clinical conditions and traumas made by the emergency control center. Clinical conditions comprised cardiovascular affections, neurological syndromes, and respiratory failure, due to their time-sensitive nature; traumatic injuries consisted of those caused by automobile accidents and falls, as they were the most prevalent in the service. This was a cross-sectional retrospective study with a sample of 1,580 cases from 2013, of which 739 were clinical conditions and 787 were traumatic injuries. Data were extracted from the SAMU call center’s computer system of the city of Porto Alegre (SAPH True), and then transposed to Microsoft Excel and analyzed using the Statistical Package for the Social Sciences (SPSS), version 21.0. The results showed that median total response time was 19 minutes and the factors that were statistically associated with greater total response time, after adjustment by the multivariate model, were: type of clinical assistance (p<0.001), night shift (p<0.001), basic team (p=0.016), week business days (p<0.001), and the occurrence of an incident at the call location (p=0.001). There were no significant differences in RT in terms of age range and emergency severity. Total response time, defined as the sum of the time elapsed in each phase of emergency care, was influenced by the performance of health professionals in communicating and assessing user demands and team mobilization for departure. Response time can be reduced by means of continuing education processes with the service professionals to discuss and reorganize the practices, implementing measures to plan the service’s structural organization. / El tiempo de respuesta es un indicador usado para evaluación de calidad de atención de emergencias prehospitalarias (AEP). Es el intervalo temporal entre la solicitud del pedido de socorro hasta la llegada del equipo al lugar del evento. Se objetivó entonces analizar el indicador de tiempo-respuesta de un Servicio de Atención Móvil de Urgencias (SAMU) respecto de llamadas para urgencias clínicas y traumáticas realizadas a la Central de Regulación de Urgencias. Las urgencias clínicas consistieron en afecciones cardiovasculares, síndromes neurológicos y disfunciones respiratorias, consideradas urgencias tiempo-dependientes; las urgencias traumáticas constituyeron accidentes de tránsito y caídas, las más prevalentes en el servicio. Estudio retrospectivo transversal, con muestra constituida por 1580 atenciones realizadas en 2013, 793 clínicas y 787 traumáticas. Los datos se tomaron del sistema informático de la central de regulación del SAMU de Porto Alegre (SAPH True), fueron volcados a planilla de Microsoft Excel y analizados con Statistical Package for the Social Sciences (SPSS), versión 21.0. Los resultados evidencian que el tiempo de respuesta total tiene una mediana de 19 minutos, y los factores que permanecieron estadísticamente asociados al mayor tiempo de respuesta total luego del ajuste por modelo multivariado fueron: tipo de socorro clínico (p<0,001), turno nocturno (p<0,001), equipo básico (p=0,016), días hábiles (p<0,001) y acontecimiento de incidente en el lugar del llamado (p=0,001). Respecto a la faja etaria y gravedad presumida, no hay diferencias significativas de TR. El TR total, integrado por la sumatoria de lapsos de tiempo de cada etapa de atención, resulta influido por el desempeño de los profesionales en comunicación y evaluación de solicitudes del usuario, y preparación del equipo para salida de atención. El tiempo de respuesta podrá ser reducido a través de procesos de educación permanente con los profesionales actuantes en el servicio para discusión y reorganización de prácticas y con medidas de planificación en la organización estructural del SAMU.

O objetivo do presente trabalho foi determinar o papel da integração sensório-motora sobre o efeito do estímulo precedente visual. A investigação também teve a intenção de delimitar a estratégia relacionada à modulação do efeito do estímulo precedente. Para isso, foram utilizadas variações de tarefas de tempo de reação (TR) de escolha, e os dados de TR e acurácia foram analisados. Encontramos uma propensão a antecipar respostas na tarefa de TR de escolha de local, devido ao aparecimento do estímulo precedente. A análise revelou uma troca velocidade-acurácia, indicativa de mudança no critério. Uma adaptação da Teoria de Detecção de Sinais mostrou que o critério de decisão foi elevado, evitando erros de antecipação e de alarmes falsos. A tarefa de TR de escolha de forma apresentou diminuição nos tempos de reação no local do estímulo precedente, sem trocas de velocidade por acurácia. Nossos resultados principais indicam que a integração de estímulo e resposta pode interferir no efeito do estímulo precedente através de modulações de estratégia, dependentes de características do estímulo relevantes à tarefa em questão. / The aim of the present work was to determine the role of sensory-motor integration on the effect of the visual prime stimulus. The investigation intended also to delimit the strategy related to this prime stimulus effect modulation. In order to do that, variations of choice reaction time (RT) task were used, and RT and accuracy data were analyzed. We found a propensity to anticipate responses in the location-based choice RT task, due to the onset of the prime stimulus. The analysis revealed a speed-accuracy trade-off, indicative of criterion shift. An adaptation of the Signal Detection Theory showed that the decision criterion was raised, avoiding anticipatory and false alarm errors. The form-based choice RT task presented decrease in response time in the prime stimulus location, with no speed-accuracy trade-offs. Our main results indicate that stimulus-response integration can interfere with the prime stimulus effect through strategic modulations dependent on stimuli features relevant to the task in hand.

A ocorrência de um estímulo auditivo imediatamente antes de um estímulo alvo visual reduz o tempo de reação em dezenas de milisegundos, um efeito atribuído a atenção temporal automática. O presente estudo investigou se este efeito é resultante de uma facilitação de mecanismos sensoriais. Dois experimentos foram realizados. No primeiro, foi realizada uma tarefa de tempo de reação simples por meio da resposta a estímulos alvos visuais com variações em sua detectabilidade. Esperava-se que o tamanho do efeito facilitador pudesse aumentar com o aumento da dificuldade de detecção do alvo. No segundo experimento foi realizada uma tarefa de acurácia. Os dados foram analisados pela teoria de detecção de sinais. Esperava-se que o estímulo precedente possibilitasse o aumento da detectabilidade do alvo e redução do critério de resposta. No primeiro experimento, não houve influência do estímulo precedente no aumento da detectabilidade do alvo. Os resultados do segundo experimento indicaram haver influência do estímulo precedente no aumento da detectabilidade do alvo e redução do critério pra a resposta. Esses resultados reforçam a teoria de que a atenção temporal automática facilita o processamento sensorial. / The occurrence of an auditory stimulus immediately before a visual target stimulus shortens reaction time by tens of milliseconds, an effect attributed to automatic temporal expectation. The present study investigated whether this effect results from a facilitation of sensory mechanisms. Two experiments were performed. In the first one the volunteers performed a simple reaction time task. They responded to visual targets which differ in detectability. It was expected that the size of the facilitatory effect would increase with the difficulty of target detection. In the second experiment the volunteers performed an accuracy task. Its data were analyzed on basis of signal detection theory. It was expected that the warning stimulus would increase the detectability of the target and lower the criterion to respond. The results of the first experiment did not indicate any influence of target detectability. The results of the second experiment indicate that both the detectability of the target and the criterion to respond were affected by the warning stimulus. These results provide support to the idea that automatic temporal expectancy facilitates sensory processing.