abstract: Timing performance is sensitive to fluctuations in time and motivation, thus interval timing and motivation are either inseparable or conflated processes. A behavioral systems model (e.g., Timberlake, 2000) of timing performance (Chapter 1) suggests that timing performance in externally-initiated (EI) procedures conflates behavioral modes differentially sensitive to motivation, but that response-initiated (RI) procedures potentially dissociate these behavioral modes. That is, timing performance in RI procedures is expected to not conflate these behavioral modes. According to the discriminative RI hypothesis, as initiating-responses become progressively discriminable from target responses, initiating-responses increasingly dissociate interval timing and motivation. Rats were trained in timing procedures in which a switch from a Short to a Long interval indexes timing performance (a latency-to-switch, LTS), and were then challenged with pre-feeding and extinction probes. In experiments 1 (Chapter 2) and 2 (Chapter 3), discriminability of initiating-responses was varied as a function of time, location, and form for rats trained in a switch-timing procedure. In experiment 3 (Chapter 4), the generalizability of the discriminative RI hypothesis was evaluated in rats trained in a temporal bisection procedure. In experiment 3, but not 1 and 2, RI enhanced temporal control of LTSs relative to EI. In experiments 1 and 2, the robustness of LTS medians to pre-feeding but not extinction increased with the discriminability of initiating-responses from target responses. In experiment 3, the mean LTS was robust to pre-feeding in EI and RI. In all three experiments, pre-feeding increased LTS variability in EI and RI. These results provide moderate support for the discriminative RI hypothesis, indicating that initiating-responses selectively and partially dissociate interval timing and motivation processes. Implications for the study of cognition and motivation processes are discussed (Chapter 5). / Dissertation/Thesis / Doctoral Dissertation Psychology 2018

abstract: Temporal bisection is a common procedure for the study of interval timing in humans and non-human animals, in which participants are trained to discriminate between a “short” and a “long” interval of time. Following stable and accurate discrimination, unreinforced probe intervals between the two values are tested. In temporal bisection studies, intermediate non-reinforced probe intervals are typically arithmetically- or geometrically- spaced, yielding point of subjective equality at the arithmetic and geometric mean of the trained anchor intervals. Brown et al. (2005) suggest that judgement of the length of an interval, even when not reinforced, is influenced by its subjective length in comparison to that of other intervals. This hypothesis predicts that skewing the distribution of probe intervals shifts the psychophysical function relating interval length to the probability of reporting that interval as “long.” Data from the present temporal bisection study, using rats, suggest that there may be a within-session shift in temporal bisection responding which accounts for observed shifts in the psychophysical functions, and that this may also influence how rats categorize ambiguous intervals. / Dissertation/Thesis / Masters Thesis Psychology 2019

L’objectif de ma thèse était d’étudier de façon plus approfondie l’influence des émotions sur la perception du temps, et surtout d’essayer d’identifier les mécanismes sous-jacents, encore méconnus aujourd’hui. Pour cela, j’ai mené 6 études organisées autour de 2 axes. L’objectif de l’Axe 1 était d’identifier les mécanismes impliqués dans l’effet des émotions sur la perception de la durée de stimuli émotionnels dans une tâche de bissection temporelle. L’objectif de l’Axe 2 était d’élaborer de nouvelles techniques d’induction permettant d’observer des effets plus robustes. Les résultats révèlent un allongement subjectif du temps, avec différents types de stimuli émotionnels fortement activateurs sur le plan physiologique. Cet effet apparait avec plusieurs types de stimuli menaçants et un large éventail de durées, allant de 0.3 à 8 s. Il apparait également de manière similaire chez l’adulte et l’enfant, du moins dès l’âge de 5 ans. De plus, cette dilatation du temps n’est pas accompagnée d’une amélioration de la sensibilité au temps, même quand la discrimination temporelle s’avère difficile. L’ensemble de ces données suggère un effet robuste des émotions fortement activatrices sur le jugement du temps, qui serait expliqué principalement par des mécanismes automatiques, et provoquerait l’accélération de l’horloge interne. Dans les situations de menace, cette accélération de l'horloge permettrait d’agir le plus rapidement possible. Quand le temps passe plus vite, l’individu est plus promptement prêt à agir. Toutefois, d’autres études sont encore nécessaires pour trancher la question de l’automaticité des processus et l’absence d’effet attentionnel. / The objective of this thesis was to study more precisely the influence of emotions on time perception, and above all to try to identify the underlying mechanisms, still unknown to this day. For this, I conducted 6 studies organized around 2 axes. The goal of Axis 1 was to identify the mechanisms involved in the effect of emotions on the duration judgment of emotional stimuli in a temporal bisection task. The goal of Axis 2 was to develop new induction methods in order to observe more robust effects.The results reveal a subjective lengthening of time, with different types of highly arousing emotional stimuli. This effect appears with several types of threatening stimuli and a wide range of durations, ranging from 0.3 to 8 s. It also appears similarly in adults and children, at least from the age of 5. Moreover, this time dilatation is not accompanied by an improvement in time sensitivity, even when temporal discrimination was difficult. All of these data suggest a robust effect of highly arousing emotions on time perception, which would be explained mainly by automatic mechanisms, and would cause the acceleration of the internal clock. In a situation of danger, this clock acceleration would allow the individual to react as quickly as possible. When time goes faster, the individual is prepared to act quicker. However, further studies are still needed to resolve the issue of automatic processes and the absence of attentional effects.