The present thesis set out to investigate how sensory modality and spatial presentation influence visual and auditory duration judgments in the millisecond range. The effects of modality and spatial location were explored by considering right and left side presentations of mixed or blocked visual and auditory stimuli. Several studies have shown that perceived duration of a stimulus can be affected by various extra-temporal factors such as modality and spatial position. Auditory stimuli lead to more precise duration judgments than visual stimuli and often last subjectively longer than visual stimuli of equal duration. The circumstances under which these modality differences occur are not clear yet. Recent studies indicated an interaction between temporal and spatial processing. Overestimation of durations was associated with right side presentation of visual stimuli, underestimation with left side presentation. However, the effect of spatial presentation has not been explored in the auditory temporal judgments. Furthermore, there is a debate concerning the mechanisms underlying processing of visual and auditory intervals with some researchers supporting the view that there is a central, amodal temporal mechanism and others arguing in favour of distinct, modality specific temporal mechanisms. The above issues were examined in a series of experiments using the duration discrimination paradigm. Processing demands where varied between experiments by varying the number of stimuli positions and the way that different modality trials were presented (mixed or blocked). Across all experiments we found no effect of location either in visual or auditory domain. However, in experiments in which different modality trials were intermixed, participants in the visual versions of the task tended to overestimate durations of comparison stimuli that were presented at different locations to the standard stimuli. In such conditions, visual stimuli were also judged to be longer than the auditory. However, when the location of the comparison stimulus was at the same side as the standard a reverse effect was observed. These findings call into question an influence of the position per se on temporal judgments as the visual duration judgments were affected rather by the change of the location. Auditory judgments were not affected by location manipulations, suggesting that different mechanisms might underlie visual and auditory temporal processing. Based on these results, we propose the existence of an error-correction mechanism, according to which a specific duration is added in order to compensate for the loss of time caused by spatial attention shifts. This mechanism is revealed under some circumstances (such as mixed modality) where it is over-activated, resulting into a systematic bias. This work has important implications for the contemporary research in time perception as it is shedding new light on the possible ways that a unified experience of timing arises from modally and spatially specific temporal mechanisms.

False memories (FM´s) occur when we remember the events that never happened in reality, situations at which we were not present, and places where we never been to or when we remember some event differently from what really happened. The main purpose of this work was to check the durability of individual s memory after a time span of one week and to check the influence of the source monitoring on the creation of FM´s. For this, it was used the Deese-Roediger-McDermott (DRM) paradigm, which consists of the presentation of twelve lists of fifteen associated words (targets) to an undisclosed one which is called the critical distractor or critical nonpresented word. The individuals were picked among 80 UFU Psychology undergraduates who volunteer to participate. They were divided in two groups: auditory and visual ones. This separation was due to the difference in the modality of lists presentation at study. All participants were asked to pay attention to the words and half of them were asked to do the source monitoring of the words, whether it is auditory or visually form. Following the presentation of the twelve lists, they solved simple arithmetic problems. At last, it was done an immediate recognition memory test which has seventy words: thirty six studied itens (targets), twelve related lures (critical distractors) and twenty two unrelated lures (new words which were not semantically associated to any of the ten lists previously presented to them). One week later, they came back to do the delayed recognition memory test. The test and the procedure were the same as for the immediate recognition memory test. In these recognition tests they had to choose between Yes or No for each word, whether they did or did not recognize the words from one of the lists and they were asked to identify the word s source: Auditory or Visually form. The results showed that false memories are created and can be kept until one week later, more than real memories. Visual modality was better to the correct recognition (targets) and further more, it was responsible for the smaller rate of false recognition. Instructions to the individuals improved the source monitoring for targets, but it did not cut down on the misattribution for the critical distractor. / Falsas memórias (FM´s) podem ser definidas como o fato de nos lembrarmos de eventos que não ocorreram na realidade, de situações as quais nunca presenciamos, de lugares onde nunca estivemos, ou então, de nos lembrarmos de algum evento de maneira um pouco distorcida do que realmente aconteceu. O objetivo geral deste trabalho foi verificar a durabilidade da memória dos sujeitos ao longo de uma semana, bem como verificar a influência do monitoramento da fonte na criação de falsas memórias. Para tanto, neste estudo foi usado o procedimento de Deese/ Roediger/ McDermott (DRM) que consiste de listas de palavras associadas. O instrumento utilizado foi composto de doze listas de quinze palavras associadas (alvos) a um tema central que recebe o nome de distrator crítico e não aparece na lista. Os participantes da pesquisa foram 80 universitários do curso de Psicologia da UFU que aceitaram voluntariamente participar do estudo. Eles foram divididos em dois grupos: auditivo e visual. Esta separação foi devida a diferença da modalidade de apresentação das palavras no estudo. Foi pedido a todos que prestassem atenção às palavras e para a metade da amostra de cada grupo, foi informado que deveriam fazer o monitoramento da fonte das palavras, via auditiva ou visual. Após a apresentação das doze listas, eles fizeram uma tarefa de distração com problemas simples de matemática. Ao final, foi feito um teste de reconhecimento imediato contendo setenta palavras, sendo: trinta e seis alvos, os doze distratores críticos e vinte e duas palavras acrescentadas e que não eram semanticamente relacionadas a nenhuma das listas. Após uma semana, fizeram um teste de reconhecimento posterior, no qual receberam a mesma folha do teste de reconhecimento imediato e procederam da mesma forma. Nos testes de reconhecimento, eles tinham que assinalar a opção (Sim ou Não) em cada palavra, conforme reconhecessem ou não a palavra de alguma das listas e identificar a fonte na qual a palavra foi apresentada: auditiva ou visual. Os resultados mostraram que as falsas memórias são criadas e podem ser mantidas, após uma semana, mais do que as memórias reais. A modalidade visual foi melhor para o reconhecimento verdadeiro e foi a responsável pela menor taxa de reconhecimento falso. A instrução aos participantes melhorou o monitoramento da fonte para os alvos, mas não fez com que o índice de atribuição de fontes para os distratores críticos diminuísse. / Mestre em Psicologia Aplicada