1,720,966 research outputs found
Do musicians perceive numerosity illusions differently?
No full textA large body of experimental evidence suggests that long-term musical training has profound consequences on the functional organization of the brain, leading to an improvement of cognitive abilities that are non-primarily involved in music. Here, we tested the hypothesis stating that long- term musical training has effects in the perceptual laws underlying vision. To achieve our goal, we compared the susceptibility of musicians and non-musicians to the Solitaire illusion, an illusion of numerosity based on the Gestalt law of proximity and good continuation. Both groups were observed in a relative (Experiment 1) and an absolute (Experiment 2) numerosity task: the former required an estimation of which array contained more blue dots; the latter required an estimation of the number of blue dots presented. In both experiments, the illusory pattern was presented as well. In control trials, no difference was found between musicians and non-musicians in the overall performance. The two groups were susceptible to the illusion in both experiments, although the musicians in Experiment 2 varied in their susceptibility to the numerosity misperception, perceiving a smaller illusory ratio compared with non-musicians. Based on these results, we suggest that prolonged music training may alter the perceptual laws in visual modality
Using an Automated Operant Conditioning Procedure to Test Colour Discrimination in Two Juvenile Piranhas, Pygocentrus nattereri: A Lesson on Failures and Pitfalls and How to Avoid Them
Full text linkMost studies on the cognitive abilities of fish have focused on model organisms adopted in behavioural neuroscience. To date, little attention has been devoted to characiformes fish and we record a lack of cognitive investigation on the piranha. In this study, we conducted a preliminary set of experiments to assess whether red-bellied piranhas (Pygocentrus nattereri) can solve an automated operant conditioning task, specifically, a reversal learning task. In Experiment 1, the fish were required to discriminate between red and green, while in Experiment 2, they had to discriminate between white and yellow. In either case, we found no evidence of learning capacities with our protocol after extensive training exceeding one thousand trials overall. In Experiment 3, we simplified the learning task by using achromatic stimuli (black and white discrimination) and always presenting the reinforced stimulus on the same side of the tank (a combination of response learning and place learning). Subjects did learn how to discriminate between the colours, although no subject was able to reach the criterion in the subsequent reversal learning task, suggesting that piranhas may be limited in their cognitive flexibility. However, our training procedure may have been inefficient in addressing this issue. We outline some potential limitations of the current methodology to help to establish a more effective approach for investigating operant conditioning in this species
Investigating acoustic numerosity illusions in professional musicians
Full text linkVarious studies have reported an association between musical expertise and enhanced visuospatial and mathematical abilities. A recent work tested the susceptibility of musicians and nonmusicians to the Solitaire numerosity illusion finding that also perceptual biases underlying numerical estimation are influenced by long-term music training. However, the potential link between musical expertise and different perceptual mechanisms of quantitative estimation may be either limited to the visual modality or universal (i.e., modality independent). We addressed this question by developing an acoustic version of the Solitaire illusion. Professional musicians and nonmusicians listened to audio file recordings of piano and trombone notes and were required to estimate the number of piano notes. The stimuli were arranged to form test trials, with piano and trombone notes arranged in a way to form the Solitaire pattern, and control trials, with randomly located notes to assess their quantitative abilities in the acoustic modality. In the control trials, musicians were more accurate in numerical estimation than nonmusicians. In the presence of illusory patterns, nonmusicians differed from musicians in the esteem of regularly arranged vs. randomly arranged notes. This suggests that the association between long-term musical training and different perceptual mechanisms underlying numerical estimation may not be confined to the visual modality. However, neither musicians nor nonmusicians seemed to be susceptible to the acoustic version of the Solitaire illusion, suggesting that the emergence of this illusion may be stimulus and task-dependent
Do body colour and sociability impact scototaxis response of fish?
Full text link: Scototaxis test is an anxiety-like test used by behavioural neuroscientists consisting in the assessment of dark/light preference of laboratory animals. This test has been widely used in fish. Most of the species have been shown to express a preference for the dark environment. However, the majority of the investigated species has a dark body colour, thus making a clear contrast with a white/bright background. Also, while in nature fish tend to be highly social, studies in the scototaxis literature tested single fish. Yet, individual vs. group behaviour might interact with scototaxis response. In experiment 1, we assessed the individual response to test the hypothesis that the different colours of the body might modulate the dark/light preference. We found that species with a dark body colour (Hyphessobrycon megalopterus) and a largely transparent body colour (Kryptopterus bicirrhis) strongly preferred the darker environment. Instead, the preference for darkness of a species with a luminescent part of the body (Paracheirodon axelrodi) was less pronounced. Lastly, a species with a white body colour (Corydoras albini) did not prefer either a bright or a dark sector. In experiment 2, we explored the behaviour of these species when inserted in shoals of 20 individuals in the experimental apparatus. While H. megalopterus and K. bichirrhis confirmed their robust preference for darker environments, the other two species changed their preference. Taken together, these results suggest that scototaxis response is context-dependent, as it appears to be modulated by the body colour and the presence/absence of other conspecifics in the surrounding
Is the Susceptibility to Visual Illusions Related to the Relative Brain Size? Insights from Small-Brained Species
Full text linkVisual illusions are powerful tools to understand similarities and differences in the perceptual mechanisms of human and nonhuman animals. Such investigation is particularly important in the presence of animal species whose brains largely differ from ours, because it can reveal whether perceptual laws described in humans are strictly related to the peculiarity of large brains, as the case of mammals and birds. Here we review the literature on visual illusions in species with a much smaller relative brain size. Most works on this subject have investigated fish, whereas only a few studies have been conducted on amphibians and reptiles. Taken together, the existing literature found more similarities than differences in the perceptual mechanisms underlying size, numerosity, brightness, motion, and subjective contours among vertebrates, regardless of the high variability in the relative brain size of the species
Does brain lateralization affect the performance in binary choice tasks? A study in the animal model Danio rerio
Full text linkResearchers in behavioral neuroscience commonly observe the behavior of animal subjects in the presence of two alternative stimuli. However, this type of binary choice introduces a potential confound related to side biases. Understanding whether subjects exhibit this bias, and the origin of it (pre-existent or acquired throughout the experimental sessions), is particularly important to interpreting the results. Here, we tested the hypothesis according to which brain lateralization may influence the emergence of side biases in a well-known model of neuroscience, the zebrafish. As a measure of lateralization, individuals were observed in their spontaneous tendencies to monitor a potential predator with either the left or the right eye. Subjects also underwent an operant conditioning task requiring discrimination between two colors placed on the left-right axis. Although the low performance exhibited in the operant conditioning task prevents firm conclusions from being drawn, a positive correlation was found between the direction of lateralization and the tendency to select the stimulus presented on one specific side (e.g., right). The choice for this preferred side did not change throughout the experimental sessions, meaning that this side bias was not the result of the prolonged training. Overall, our study calls for a wider investigation of pre-existing lateralization biases in animal models to set up methodological counterstrategies to test individuals that do not properly work in a binary choice task with stimuli arranged on the left-right axis
Searching for the Critical p of Macphail’s Null Hypothesis: The Contribution of Numerical Abilities of Fish
Full text linkIn 1985, Macphail argued that there are no differences among the intellects of non-human vertebrates and that humans display unique cognitive skills because of language. Mathematical abilities represent one of the most sophisticated cognitive skills. While it is unquestionable that humans exhibit impressive mathematical skills associated with language, a large body of experimental evidence suggests that Macphail hypothesis must be refined in this field. In particular, the evidence that also small-brained organisms, such as fish, are capable of processing numerical information challenges the idea that humans display unique cognitive skills. Like humans, fish may take advantage of using continuous quantities (such as the area occupied by the objects) as proxy of number to select the larger/smaller group. Fish and humans also showed interesting similarities in the strategy adopted to learn a numerical rule. Collective intelligence in numerical estimation has been also observed in humans and guppies. However, numerical acuity in humans is considerably higher than that reported in any fish species investigated, suggesting that quantitative but not qualitative differences do exist between humans and fish. Lastly, while it is clear that contextual factors play an important role in the performance of numerical tasks, inter-species variability can be found also when different fish species were tested in comparable conditions, a fact that does not align with the null hypothesis of vertebrate intelligence. Taken together, we believe that the recent evidence of numerical abilities in fish call for a deeper reflection of Macphail’s hypothesis
Anisotropy of perceived numerosity: Evidence for a horizontal–vertical numerosity illusion
No full textMany studies have investigated whether numerical and spatial abilities share similar cognitive systems. A novel approach to this issue consists of investigating whether the same perceptual biases underlying size illusions can be identified in numerical estimation tasks. In this study, we required adult participants to estimate the number of white dots in arrays made of white and black dots displayed in such a way as to generate horizontal–vertical illusions with inverted T and L configurations. In agreement with previous literature, we found that participants tended to underestimate the target numbers. However, in the presence of the illusory patterns, participants were less inclined to underestimate the number of vertically aligned white dots. This reflects the perceptual biases underlying horizontal–vertical illusions. In addition, we identified an enhanced illusory effect when participants observed vertically aligned white dots in the T shape compared to the L shape, a result that resembles the length bisection bias reported in the spatial domain. Overall, we found the first evidence that numerical estimation differs as a function of the vertical or horizontal displacement of the stimuli. In addition, the involvement of the same perceptual biases observed in spatial tasks supports the idea that spatial and numerical abilities share similar cognitive processes
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