A dynamic neural field model of temporal order judgments

Temporal ordering of events is biased, or influenced, by perceptual organization—figure–ground organization—and by spatial attention. For example, within a region assigned figural status or at an attended location, onset events are processed earlier (Lester, Hecht, & Vecera, 2009; Shore, Spence, & Klein, 2001), and offset events are processed for longer durations (Hecht & Vecera, 2011; Rolke, Ulrich, & Bausenhart, 2006). Here, we present an extension of a dynamic field model of change detection (Johnson, Spencer, Luck, & Schöner, 2009; Johnson, Spencer, & Schöner, 2009) that accounts for both the onset and offset performance for figural and attended regions. The model posits that neural populations processing the figure are more active, resulting in a peak of activation that quickly builds toward a detection threshold when the onset of a target is presented. This same enhanced activation for some neural populations is maintained when a present target is removed, creating delays in the perception of the target’s offset. We discuss the broader implications of this model, including insights regarding how neural activation can be generated in response to the disappearance of information. (PsycINFO Database Record (c) 2015 APA, all rights reserved

Attending to the parts of a single object: Part-based selection limitations

La temática engloba a todos aquellos con patologías susceptibles de ser compensada por una prótesis. Las mismas, para uso competitivo, son importadas y de costo prohibitivo sobre todo en vistas de la iniciación en su uso. Es una tecnología capaz de desarrollarse en el país logrando mayor índice de inclusión a temprana edad e igualdad de condiciones para nuestros atletas paralímpicos. El objetivo es generar el conocimiento que nos permita obtener una prótesis capaz de resistir las solicitaciones de una competencia y desarrollar los parámetros para una rápida adaptación a cada situación particular de los futuros usuarios. Se busca establecer los procedimientos para fabricar una nueva prótesis transtibial de tipo Flex-Foot en materiales compuestos que presente tamaño y proporción apropiada, sea liviana, tenga propiedades dinámicas y elásticas adecuadas, soporte la carga y fatiga provista por el corredor.Universidad Nacional de La Plat

Spatial attention: normal processes and their breakdown

High-level vision involves processes such as object recognition, selective attention, and visuomotor action, at the interface of perception and cognition. This article focuses on selective attention, a set of processes that allows selection of some stimuli over others and performance of multiple tasks in a coordinated manner Before discussing spatial attention, this article addresses what attention is, and what it is useful for. A common view is that attentional processes are required because the environment contains more information than can be processed and comprehended at any given time. Attentional processes can be viewed as protecting an organism from information overload and are selective in that they allow processing of some stimuli while disregarding others. The stimuli that are selected may become attended for several reasons. For example, when faced with much sensory input, an optimal strategy is to attend to those that are relevant to current behavior. For example, a driver's distance from a lead vehicle is relevant for the task of safe driving, but cell phone conversation generally is not. The processes that permit an organism to choose some environmental inputs over others are referred to collectively as attention

Graded effects in hierarchical figure-ground organization: A reply to Peterson

An important issue in vision researc

Serialization of Behavior During Car Following in Older Drivers

Age-related declines in cognitive functioning can push older adults to adopt strategies that may or may not improve their driving safety. Previous research suggests one strategy involves performing complex driving tasks (e.g., right turn negotiation) in discrete steps (“serialization”) rather than fluidly. The current study used simulator scenarios developed to test possible age-related serialization of behavior during complex car following. In all scenarios, participants closely monitored a lead vehicle using sustained attention. During multi-tasking scenarios, drivers performed an additional localization task designed to increase the demands on attention. The results demonstrate that older adults showed general impairments in multi-tasking and vehicle control during car following. Importantly, ageassociated changes in task execution were observed, demonstrating older adults also serialize car following behavior under certain conditions. As a result, older drivers withdrew attention from the lead vehicle for several seconds. This pattern of behavior identifies a remediable situation where age-associated impairments may increase crash risk

Attentional capture under high perceptual load.

Attentional capture by abrupt onsets can be modulated by several factors, including the complexity, or perceptual load, of a scene. We have recently demonstrated that observers are less likely to be captured by abruptly appearing, task-irrelevant stimuli when they perform a search that is high, as opposed to low, in perceptual load Scenes contain a tremendous amount of information, often more than an observer can process at one time. As a result, selective attention mechanisms have developed that allow us to focus only on the information most relevant for carrying out our goals. For example, when attempting to read a newspaper in a crowded coffeehouse, we focus on the words on the page and ignore the irrelevant sights and sounds around us. Such goal-directed attentional control allows us to focus on the task at hand without interruption from extraneous information. However, sometimes our attention is captured by salient information in the environment regardless of its relevance to our goals. This type of stimulus-driven attentional capture is ubiquitous and can cause us to shift away from our primary goals and attend to information outside of our current focus

Changes in area affect figure–ground assignment in pigeons

A critical cue for figure–ground assignment in humans is area: smaller regions are more likely to be perceived as figures than are larger regions. To see if pigeons are similarly sensitive to this cue, we trained birds to report whether a target appeared on a colored figure or on a differently colored background. The initial training figure was either smaller than (Experiments 1 and 2) or the same area as (Experiment 2) the background. After training, we increased or decreased the size of the figure. When the original training shape was smaller than the background, pigeons’ performance improved with smaller figures (and worsened with larger figures); when the original training shape was the same area as the background, pigeons’ performance worsened when they were tested with smaller figures. A smaller figural region appeared to improve the figure–ground discrimination only when size was a relevant cue in the initial discrimination

Does hand position affect orienting when no action is required? An electrophysiological study

Previous research has shown that attention can be biased to targets appearing near the hand that require action responses, arguing that attention to the hand facilitates upcoming action. It is unclear whether attention orients to non-targets near the hand not requiring responses. Using electroencephalography/event-related potentials (EEG/ERP), this study investigated whether hand position affected visual orienting to non-targets under conditions that manipulated the distribution of attention. We modified an attention paradigm in which stimuli were presented briefly and rapidly on either side of fixation; participants responded to infrequent targets (15%) but not standard non-targets and either a hand or a block was placed next to one stimulus location. In Experiment 1, attention was distributed across left and right stimulus locations to determine whether P1 or N1 ERP amplitudes to non-target standards were differentially influenced by hand location. In Experiment 2, attention was narrowed to only one stimulus location to determine whether attentional focus affected orienting to non-target locations near the hand. When attention was distributed across both stimulus locations, the hand increased overall N1 amplitudes relative to the block but not selectively to stimuli appearing near the hand. However, when attention was focused on one location, amplitudes were affected by the location of attentional focus and the stimulus, but not by hand or block location. Thus, hand position appears to contribute only a non-location-specific input to standards during visual orienting, but only in cases when attention is distributed across stimulus locations

Toward a biased competition account of object-based segregation and attention

Abstract. Because the visual system cannot process all of the objects, colors, and features present in a visual scene, visual attention allows some visual stimuli to be selected and processed over others. Most research on visual attention has focused on spatial or location-based attention, in which the locations occupied by stimuli are selected for further processing. Recent research, however, has demonstrated the importance of objects in organizing (or segregating) visual scenes and guiding attentional selection. Because of the long history of spatial attention research, theories of spatial attention are more mature than theories of other visual processes, such as object segregation and object attention. In the present paper, I outline a biased competition account of object segregation and attention, following similar accounts that have been developed for spatial attention (Desimone and Duncan, 1995). In my biased competition account, I seek to understand how some objects can be segregated and selected over other objects in a complex visual scene. Under this account, there are two sources of visual information that allow an object to be processed over other objects: bottom-up information carried by the physical stimulus and top-down information based on an observer’s goals. I use the biased competition account to combine many diverse findings from the object segregation and attention literatures into a common framework

What Are You Looking at? Impaired 'social Attention' Following Frontal-Lobe Damage

Abstract Humans are able to predict the behavior of others. Several studies have investigated this capability by determining if social cues, such as eye gaze direction, can influence the allocation of visual attention. When a viewer sees a face looking to the left, the viewer's attention is allocated in the gazed-at direction. These 'social attention' studies have asked if this allocation of attention is automatic or under voluntary control. In this paper, we show that a patient with frontal-lobe damage is impaired at allocating attention to peripheral locations voluntarily, although attention can be allocated there automatically. The patient, EVR, can use peripheral cues to selectively process one location over another but cannot use symbolic cues (words) to allocate attention. EVR is also impaired in using eye gaze cues to allocate attention, suggesting that 'social attention' may involve frontal-lobe processes that control voluntary, not automatic, shifts of visuospatial attention