It is known that moving visual stimuli (bouncing balls) have an advantage over static visual ones (flashes) in sensorimotor synchronization, such that the former match auditory beeps in driving synchronization while the latter do not. This occurs in beat-based synchronization but not in beat-based purely perceptual tasks, suggesting that the advantage is action-specific. The main goal of this study was to test the advantage of moving over static visual stimuli in a different perceptual timing system – duration-based perception – to determine whether the advantage is action-specific in a broad sense, i.e., if it excludes both beat-based and duration-based perception. We asked a group of participants to perform different tasks with three stimulus types: auditory beeps, visual bouncing balls (moving) and visual flashes (static). First, participants performed a duration-based perception task in which they judged whether intervals were speeding up or slowing down; then they did a synchronization task with isochronous sequences; finally, they performed a beat-based perception task in which they judged whether sequences sounded right or wrong. Bouncing balls outperformed flashes and matched beeps in synchronization. In the duration-based perceptual task, beeps, balls and flashes were equivalent, but in beat-based perception beeps outperformed balls and flashes. Our findings suggest that the advantage of moving over static visual stimuli is grounded on action rather than perception in a broad sense, in that it is absent in both beat-based and duration-based perception.

Dyslexics underperform controls in estimating and comparing time intervals defined by visual stimuli. Accuracy in vision-based duration perception requires efficient processing of visual events because these will define the onset and offset of time intervals. Since dyslexics have difficulties processing dimensions of visual stimuli like luminance contrasts and motion, we do not know the extent to which these visual deficits are responsible for their difficulties in judging time intervals. To address this gap, we asked adults with dyslexia and matched controls to perform an interval comparison task involving five different types of visual stimuli with different levels of challenge regarding luminance contrasts and motion. If the expected disadvantage of dyslexics in visual duration perception increased for stimuli requiring increased luminance or motion processing, this would indicate that visual processing plays a role. Results showed poorer time discrimination in dyslexics, but this disadvantage did not change according to stimulus type. Complementary analyses of oculomotor behavior during the task suggested that the poorer timing performance of dyslexics may relate instead to attention and/or engagement with the task. Our findings strengthen the evidence in favor of visual duration perception deficits in dyslexia, but not the hypothesis that these result from purely visual problems.

Objective:To evaluate whether exposing rats to individual or combined environmental stressors triggers endophenotypes related to mood and anxiety disorders, and whether this effect depends on the nature of the behavior (i.e., innate or learned).Methods:We conducted a three-phase experimental protocol. In phase I (baseline), animals subjected to mixed schedule of reinforcement were trained to press a lever with a fixed interval of 1 minute and a limited hold of 3 seconds. On the last day of phase I, an open-field test was performed and the animals were divided into four experimental groups (n=8/group). In phase II (repeated stress), each group was exposed to either hot air blast (HAB), paradoxical sleep deprivation (PSD) or both (HAB+PSD group) on alternate days over a 10-day period. Control group animals were not exposed to stressors. In phase III (post-stress evaluation), behavior was analyzed on the first (short-term effects), third (mid-term effects), and fifth (long-term effects) days after repeated stress.Results:The PSD group presented operant hyperactivity, the HAB group presented spontaneous hypoactivity and anxiety, and the HAB+PSD group presented spontaneous hyperactivity, operant hypoactivity, impulsivity, loss of interest, and cognitive impairment.Conclusion:A combination of environmental stressors (HAB and PSD) may induce endophenotypes related to bipolar disorder.

It is known that dyslexics underperform controls in time perception tasks using visual stimuli. However, it remains undetermined whether this deficit is secondary to problems in visual, time-unrelated domains, such as luminance contrasts and/or motion processing. To address this gap, we asked adults with dyslexia and matched controls to perform an interval comparison task involving five different types of visual stimuli with different levels of challenge regarding luminance contrasts and motion. Results showed poorer time discrimination in adults with dyslexia, but this group-related disadvantage did not change according to stimulus type. Complementary analyses of oculomotor behavior during the task suggested that the poorer timing performance of dyslexics may relate to attention and/or engagement with the task. Our findings strengthen the evidence in favor of time perception deficits in dyslexia, but they do not support the hypothesis that these are secondary to visual problems.

RESUMORestrição temporal de consumo diário de água é um dos vários procedimentos manipulados para garantir a efetividade da água como um reforçador em estudos de condicionamento operante. O presente artigo apresenta dados dos pesos de dezessete ratos machos adultos Wistar que foram submetidos à restrição de trinta minutos ou uma hora de consumo de água por dia, mas sem restrição sobre alimento. Sob restrição hídrica, o peso dos animais diminuiu gradual e progressivamente. As interrupções no procedimento de restrição resultaram em ganho imediato de peso, seguido por uma resistência à diminuição de peso a níveis anteriormente registrados. Os resultados replicam àqueles encontrados na literatura analítico-comportamental sobre o padrão da variação de peso em ratos Wistar, submetidos à restrição hídrica, e fornecem parâmetros pré-experimentais para a pesquisa comportamental.Palavras-chave: ratos machos, Wistar, restrição hídrica, peso corporal, privação.ABSTRACT Temporal restriction of daily water consumption is one of several procedures manipulated to ensure the effectiveness of water as a reinforcer in studies of operant conditioning. This article shows the weights of seventeen adult male Wistar rats that underwent restraint thirty minutes or an hour of water consumption per day, but no restriction on food. Under hydric restriction, the weight of the animals decreased gradually and progressively. The interruptions restriction procedure resulted in an immediate weight gain, followed by a weight loss resistance at levels previously reported. The results replicate those found in the behavior-analytic literature on the pattern of weight changes in rats subjected to hydric restriction, and provide pre-experimental parameters for behavioral research.