Search

Duration perception abilities seem to enhance reading skills, but the reason for this remains under debate. Some studies focused on the ability to perceive the length of sounds (speech-related duration perception), while others approached general time skills (using, e.g., beep stimuli), but a direct comparison between the two modalities has not been done so far. In the present study, we compared the relevance of domain-general (comparison of time intervals defined by beeps) vs. speech-specific duration perception (pre-attentive EEG responses to different consonants) as statistical predictors of reading in adults. Reading included word and pseudoword decoding, as well as reading comprehension. We made regression-based analyses with the two time-related predictors for each reading skill. Pseudoword decoding was the only reading skill that was significantly predicted by duration perception, and this happened for domain-general duration perception only. Our findings strengthen the idea that skilled duration perception enhances phonological coding and its impact on grapheme-to-phoneme conversion processes. They also suggest that the benefits to phonological encoding are not specifically related to better processing of speech sound durations. Instead, the impact of skilled duration perception may rely on its connection to entrainment-to-speech skills, and the enhanced encoding of speech units that comes with it.

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.

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.

A sincronização com estímulos visuais em movimento (e.g., bolas a saltar) é mais eficaz que a sincronização com estímulos visuais estáticos (e.g., flash, ou imagem estática intermitente), e os primeiros são tão eficazes como os estímulos auditivos (bipes) enquanto os segundos não são. A vantagem dos estímulos visuais em movimento ocorre na sincronização com uma batida, mas não em tarefas de perceção temporal envolvendo uma batida, sugerindo que se trata de uma vantagem específica da ação. Neste estudo, testámos se a vantagem dos estímulos visuais em movimento ocorre num sistema percetual diferente, envolvendo durações absolutas. Um grupo de participantes foi submetido a diferentes provas, utilizando três tipos de estímulos: bipes (auditivos), bolas (visuais) em movimento e bolas (visuais) estáticas e intermitentes. As provas foram divididas em três fases: (1) Perceção da duração (intervalos a acelerar ou a atrasar), (2) Sincronização com estímulos isócronos, (3) Perceção baseada em batidas (sequências corretas ou incorretas). Os resultados da sincronização reforçaram a evidência de que as bolas em movimento são mais eficazes que bolas estáticas, e tão eficazes como os bipes. Na perceção baseada em durações, não houve efeito do estímulo, enquanto que, na perceção baseada em batidas, os bipes superaram tanto as bolas em movimento quanto as estáticas. Os resultados sugerem que a vantagem dos estímulos visuais em movimento em relação aos estímulos visuais estáticos é, num sentido amplo, específica da sincronização, visto que esta vantagem está ausente nos dois sistemas de perceção temporal (duração e batida).

Restrição 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., 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. Keywords: male rats, Wistar, hydric restriction, body weight, deprivation.