Attention makes moving objects be perceived to move faster

AbstractAlthough it is well established that attention affects visual performance in many ways, by using a novel paradigm [Carrasco, M., Ling, S., & Read. S. (2004). Attention alters appearance. Nature Neuroscience, 7, 308–313.] it has recently been shown that attention can alter the perception of different properties of stationary stimuli (e.g., contrast, spatial frequency, gap size). However, it is not clear whether attention can also change the phenomenological appearance of moving stimuli, as to date psychophysical and neuro-imaging studies have specifically shown that attention affects the adaptability of the visual motion system. Here, in five experiments we demonstrated that attention effectively alters the perceived speed of moving stimuli, so that attended stimuli were judged as moving faster than less attended stimuli. However, our results suggest that this change in visual performance was not accompanied by a corresponding change in the phenomenological appearance of the speed of the moving stimulus

Independent circuits in basal ganglia and cortex for the processing of reward and precision feedback

In order to understand human decision making it is necessary to understand how the brain uses feedback to guide goal-directed behavior. The ventral striatum (VS) appears to be a key structure in this function, responding strongly to explicit reward feedback. However, recent results have also shown striatal activity following correct task performance even in the absence of feedback. This raises the possibility that, in addition to processing external feedback, the dopamine-centered reward circuit might regulate endogenous reinforcement signals, like those triggered by satisfaction in accurate task performance. Here we use functional magnetic resonance imaging (fMRI) to test this idea. Participants completed a simple task that garnered both reward feedback and feedback about the precision of performance. Importantly, the design was such that we could manipulate information about the precision of performance within different levels of reward magnitude. Using parametric modulation and functional connectivity analysis we identified brain regions sensitive to each of these signals. Our results show a double dissociation: frontal and posterior cingulate regions responded to explicit reward but were insensitive to task precision, whereas the dorsal striatum - and putamen in particular - was insensitive to reward but responded strongly to precision feedback in reward-present trials. Both types of feedback activated the VS, and sensitivity in this structure to precision feedback was predicted by personality traits related to approach behavior and reward responsiveness. Our findings shed new light on the role of specific brain regions in integrating different sources of feedback to guide goal-directed behavior

Supernova Classes and Subclasses

The discovery of many objects with unprecedented, amazing observational characteristics caused the last decade to be the most prolific period for the supernova research. Many of these new supernovae are transitional objects between existing classes, others well enter within the defined classes, but still show unique properties. This makes the traditional classification scheme inadequate to take into account the overall SN variety and, consequently, requires the introduction of new subclasses.Comment: 10 pages, 2 figure, review for "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCra

Microsaccadic response during inhibition of return in a target–target paradigm

AbstractThis study examined the relationship between inhibition of return (IOR) in covert orienting and microsaccade statistics. Unlike a previous study [Galfano, G., Betta, E., & Turatto, M. (2004)], IOR was assessed by means of a target–target paradigm, and microsaccade dynamics were monitored as a function of both the first and the second visual event. In line with what has been reported with a cue-target paradigm, a significant directional modulation was observed opposite to the first visual event. Because participants were to respond to any stimulus, this rules out the possibility that the modulation resulted from a generic motor inhibition, showing instead that it is peculiarly coupled to the oculomotor system. Importantly, after the second visual event, a different response was observed in microsaccade orientation, whose direction critically depended of whether the second visual event appeared at the same location as the first visual event. The results are consistent with the notion that IOR is composed of both attentional and oculomotor components, and challenge the view that covert orienting paradigms engage the attentional component in isolation

Crossmodal object-based attention: auditory objects affect visual processing

Abstract According to the object-based view, visual attention can be deployed to "objects" or perceptual units, regardless of spatial locations. Recently, however, the notion of object has also been extended to the auditory domain, with some authors suggesting possible interactions between visual and auditory objects. Here we show that task-irrelevant auditory objects may affect the deployment of visual attention, providing evidence that crossmodal links can also occur at an object-based level. Hence, in addition to the well documented control of visual objects over what we hear, our findings demonstrate that, in some cases, auditory objects can affect visual processing. q 2005 Elsevier B.V. All rights reserved. Keywords: Crossmodal attention; Object-based attention; Auditory objects; Sensory modalities Attention is an important cognitive function by means of which the human cognitive system is able to select the information relevant for the current behaviour. According to the "space-based" vie

Context matters: Domestic chicks\u2019 short- and long-term habituation of freezing to a sudden acoustic stimulus

Habituation, a response decrement to an irrelevant stimulus across repeated presentations, is often described as the simplest form of non-associative learning, and it is often considered to be stimulus-specific1. However, associative models of habituation have been proposed, according to which a stimulus-context association is established in long-term memory when a stimulus is presented repeatedly2. If habituation is context-specific, the habituated response to the same stimulus should not transfer from one context to another3-5. We reared 51 chicks (Gallus gallus) in cages with an imprinting object as social companion for 2 days. On the next 2 days, all chicks underwent 2 daily sequences, 1 hour apart, of 5 sudden burst of white noise (250 ms), one every 30-60 seconds. Chicks could be administered the stimulation in the following conditions: a) always within a running wheel; b) one day in the home-cage and the next in the wheel; c) in a cage-replica placed in the same experimental room of the wheel and the next day in the wheel. Number and duration of stops of running in the wheel were the measures of chicks\u2019 freezing response. When tested in the wheel, chicks stimulated in their home-cage froze significantly more than those stimulated always in the wheel, and those stimulated in the cage-replica before being moved in the wheel. Chicks stimulated in the same environment (the experimental room) but in different contexts (wheel vs. cage-replica), showed a comparable level of habituation overall. However, a higher proportion of stops revealed a modulation of context when chicks were moved from the cage-replica to the wheel as compared to those stimulated only in the wheel. We documented in newborn chickens the presence of a sophisticated mechanism of associative learning that cannot be accounted for by classic non-associative models of habituation. Our data show that habituation relies both on local contextual and broader environmental information, which are not necessarily based on visual cues, and that probably involve other sensory information

Short-term memory mechanisms of habituation in the domestic chick (Gallus gallus)

Habituation and dishabituation reflect two forms of experience-dependent plasticity. Habituation consists of a response decrement to a reiterated irrelevant stimulus, whereas dishabituation consists in the recovery of the response to the habituated stimulus when a new one is presented. Dishabituation would arise because the model of the habituated stimulus stored in short-term memory (STM) is perturbed by the novel sensory input. Studying the ontogeny of these processes can shed light on the development of the underlying memory mechanisms. We investigated habituation and dishabituation of the freezing response to a sudden acoustic stimulation in newly hatched chicks (N=36) by comparing two early developmental ages (1 day vs. 3 days after hatching). The results showed that dishabituation was fully present a few hours after hatching, indicating that in this precocial avian species habituation and dishabituation share the same developmental trajectory, and that the underlying STM mechanisms are fully and simultaneously operative soon after birth. Moreover, the amount of habituation, after dishabituation, was larger in 1-day-old than in 3-day-old chicks, in agreement with previous findings showing a rapid attenuation of plasticity soon after birth in this avian species. Our results support the hypothesis that dishabituation represents a disruption of the habituation model stored in STM, but also indicate that dishabituation does not necessarily appear at later stages of development compared to habituation as previously postulated in other species