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We studied visual perception using an annular random-dot motion stimulus called the racetrack. We recorded neural activity using magnetoencephalography while subjects viewed variants of this stimulus that contained no inherent motion or various degrees of embedded motion. Subjects reported seeing rotary motion during viewing of all stimuli. We found that, in the absence of any motion signals, patterns of brain activity differed between states of motion perception and nonperception. Furthermore, when subjects perceived motion, activity states within the brain did not differ across stimuli of different amounts of embedded motion. In contrast, we found that during periods of nonperception brain-activity states varied with the amount of motion signal embedded in the stimulus. Taken together, these results suggest that during perception the brain may lock into a stable state in which lower-level signals are suppressed. racetrack illusion | visual motion perception doi/ 10.1073/pnas.1009857108

Correctly integrating sensory information across different modalities is a vital task, yet there are illusions which cause the incorrect localization of multisensory stimuli. A common example of these phenomena is the 'ventriloquism effect.' In this illusion, the localization of auditory signals is biased by the presence of visual stimuli. For instance, when a light and sound are simultaneously presented, observers may erroneously locate the sound closer to the light than its actual position. While this phenomenon has been studied extensively in azimuth at a single depth, little is known about the interactions of stimuli at different depth planes. In the current experiment, virtual acoustics and stereo-image displays were used to test the integration of visual and auditory signals across azimuth and depth. The results suggest that greater variability in the localization of sounds in depth may lead to a greater bias from visual stimuli in depth than in azimuth. These results offer interesting implications for understanding multisensory integration. DOI 10.2466/22.24.27.PMS.111.6.872-892

A white disk presented inside a small concentric circle (a display like the Delboeuf figure) looks lighter than when inside a larger one. The magnitude of the effect was measured with 20 observers (10 women, 10 men; ages 19 to 26 years). The decrements in luminance of the disk inside the smaller circle, in order to match the lightness of the disk inside the larger circle, are reported for three different grey backgrounds and correspond to 9.13, 10.33, and 10.46%. DOI 10.2466/24.27.PMS.111.6.799-804

Nosofsky (1983) reported that additional stimulus presentations within a trial increase discriminability in absolute identification, suggesting that each presentation creates an independent stimulus representation, but it remains unclear whether exposure duration or the formation of independent representations improves discrimination in such conditions. Experiment 1 replicated Nosofsky's result. Experiments 2 (masking the ISI between two-presentations) and 3 (manipulating stimulus duration without changing number of presentations or overall trial duration) ruled out an explanation in terms of extended opportunities for stimulus sampling, from either a sensory buffer during additional ISis or increased stimulus exposure, respectively. Experiment 4 (comparing two and three-presentations, other factors controlled) provided some limited additional support for Nosofsky's original claim that additional stimulus presentations can create either independent or duplicate representations. Experiments 5 and 6 (both manipulating ISI) demonstrated that a key factor in the additional stimulus presentation effect is the overall trial duration. We discuss the results in relation to models of absolute identification, their relative emphasis on stimulus sampling versus response selection, and the mechanisms by which duplicate representations could be created. Keywords: absolute identification, stimulus sampling, perceptual cognition, mathematical models DOI: 10.1037/a0020562

Participants' eye movements were monitored while they read sentences in which high-frequency and low-frequency target words were presented either in normal font (e.g., account) or case alternated (e.g., aCcOuNt). The influence of the word frequency and case alternation manipulations on fixation times was examined. Although both manipulations had comparable effects on standard first-pass fixation measures, word frequency, but not case alternation was found to influence the duration of the first fixation in trials with multiple first-pass fixations. Assuming that lexical processing is more often incomplete at the termination of the first in multiple first-pass fixations than at the end of single first-pass fixations, the present findings provide strong evidence for an influence of word frequency on early lexical processing. Importantly, such a demonstration of a fast acting influence of a lexical variable on fixation times satisfies a critical prerequisite for establishing lexical control of eye movements in reading. Keywords: eye movements, reading, lexical processing, word frequency, case alternation DOI: 10.1037/a0019959

We investigated distractor processing in a dual-target rapid serial visual presentation (RSVP) task containing familiar objects, by measuring repetition priming from a priming distractor (PD) to Target 2 (T2). Priming from a visually identical PD was contrasted with priming from a PD in a different orientation from T2. We also tested the effect of attention on distractor processing, by placing the PD either within or outside the attentional blink (AB). PDs outside the AB induced positive priming when they were in a different orientation to T2 and no priming, or negative priming, when they were perceptually identical to T2. PDs within the AB induced positive priming regardless of orientation. These findings demonstrate (1) that distractors are processed at multiple levels of representation; (2) that the view-specific representations of distractors are actively suppressed during RSVP; and (3) that this suppression fails in the absence of attention. Keywords: distractor processing, distractor inhibition, attentional blink, object orientation DOI: 10.1037/a0019218

Locomoting through the environment typically involves anticipating impending changes in heading trajectory in addition to maintaining the current direction of travel. We explored the neural systems involved in the 'far road' and 'near road' mechanisms proposed by Land and Horwood (1995) using simulated forward or backward travel where participants were required to gauge their current direction of travel (rather than directly control it). During forward egomotion, the distant road edges provided future path information, which participants used to improve their heading judgments. During backward egomotion, the road edges did not enhance performance because they no longer provided prospective information. This behavioral dissociation was reflected at the neural level, where only simulated forward travel increased activation in a region of the superior parietal lobe and the medial intraparietal sulcus. Providing only near road information during a forward heading judgment task resulted in activation in the motion complex. We propose a complementary role for the posterior parietal cortex and motion complex in detecting future path information and maintaining current lane positioning, respectively. Keywords: heading, superior parietal lobe, intraparietal sulcus, motion complex, road features DOI: 10.1037/a0018728

Prior research indicates that synchronized tapping performance is very poor with flashing visual stimuli compared with auditory stimuli. Three finger-tapping experiments compared flashing visual metronomes with visual metronomes containing a spatial component, either compatible, incompatible, or orthogonal to the tapping action. In Experiment 1, synchronization success rates increased dramatically for spatio-temporal sequences of both geometric and biological forms over flashing sequences. In Experiment 2, synchronization performance was best when target sequences and movements were directionally compatible (i.e., simultaneously down), followed by orthogonal stimuli, and was poorest for incompatible moving stimuli and flashing stimuli. In Experiment 3, synchronization performance was best with auditory sequences, followed by compatible moving stimuli, and was worst for flashing and fading stimuli. Results indicate that visuomotor synchronization improves dramatically with compatible spatial information. However, an auditory advantage in sensorimotor synchronization persists. Keywords: sensorimotor synchronization, visuomotor synchronization, modality effects, timing, common coding DOI: 10.1037/a0019059

Coordinated rhythmic movement is specifically structured in humans. Movement at 0[degrees] mean relative phase is maximally stable, 180[degrees] is less stable, and other coordinations can, but must, be learned. Variations in perceptual ability play a key role in determining the observed stabilities so we investigated whether stable movements can be acquired by improving perceptual ability. We assessed movement stability in Baseline, Post Training, and Retention sessions by having participants use a joystick to coordinate the movement of two dots on a screen at three relative phases. Perceptual ability was also assessed using a two-alternative forced choice task in which participants identified a target phase of 90[degrees] in a pair of displays. Participants then trained with progressively harder perceptual discriminations around 90[degrees] with feedback. Improved perceptual discrimination of 90[degrees] led to improved performance in the movement task at 90[degrees] with no training in the movement task. The improvement persisted until Retention without further exposure to either task. A control group's movement stability did not improve. Movement stability is a function of perceptual ability, and information is an integral part of the organization of this dynamical system. Keywords: perception-action, rhythmic movement coordination, perceptual learning, movement stability DOI: 10.1037/a0020412

A pictured object can be readily detected in a rapid serial visual presentation sequence when the target is specified by a superordinate category name such as animal or vehicle. Are category features the initial basis for detection, with identification of the specific object occurring in a second stage (Evans & Treisman, 2005), or is identification of the object the basis for detection? When 2 targets in the same superordinate category are presented successively (lag 1), only the identification-first hypothesis predicts lag 1 sparing of the second target. The results of 2 experiments with novel pictures and a wide range of categories supported the identification-first hypothesis and a transient-attention model of lag 1 sparing and the attentional blink (Wyble, Bowman, & Potter, 2009). Keywords: attentional blink, lag 1 sparing, picture processing, categorical search, transient attention DOI: 10.1037/a0018730

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that Gestalt grouping can indeed occur in parallel in some situations, but we demonstrate that there are also situations where Gestalt grouping becomes serial. We observe substantial time delays when image elements have to be grouped indirectly through a chain of local groupings. We call this chaining process incremental grouping and demonstrate that it can occur for only a single object at a time. We suggest that incremental grouping requires the gradual spread of object-based attention so that eventually all the object's parts become grouped explicitly by an attentional labeling process. Our findings inspire a new incremental grouping theory that relates the parallel, local grouping process to feedforward processing and the serial, incremental grouping process to recurrent processing in the visual cortex. Keywords: Gestalt grouping, perceptual organization, parallel and serial processing, visual attention, contour integration DOI: 10.1037/a0020248

Person detection is an important prerequisite of social interaction, but is not well understood. Following suggestions that people in the visual field can capture a viewer's attention, this study examines the role of the face and the body for person detection in natural scenes. We observed that viewers tend first to look at the center of a scene, and only then to fixate on a person. When a person's face was rendered invisible in scenes, bodies were detected as quickly as faces without bodies, indicating that both are equally useful for person detection. Detection was optimized when face and body could be seen, but observers preferentially fixated faces, reinforcing the notion of a prominent role for the face in social perception. These findings have implications for claims of attention capture by faces in that they demonstrate a mediating influence of body cues and general scanning principles in natural scenes. Keywords: person detection, face, body, scenes, center of gravity DOI: 10.1037/a0019057

Adaptation is ubiquitous in the human visual system, allowing recalibration to the statistical regularities of its input. Previous work has shown that global scene properties such as openness and mean depth are informative dimensions of natural scene variation useful for human and machine scene categorization (Greene & Oliva, 2009b; Oliva & Torralba, 2001). A visual system that rapidly categorizes scenes using such statistical regularities should be continuously updated, and therefore is prone to adaptation along these dimensions. Using a rapid serial visual presentation paradigm, we show aftereffects to several global scene properties (magnitude 8-21%). In addition, aftereffects were preserved when the test image was presented 10 degrees away from the adapted location, suggesting that the origin of these aftereffects is not solely due to low-level adaptation. We show systematic modulation of observers' basic-level scene categorization performances after adapting to a global property, suggesting a strong representational role of global properties in rapid scene categorization. Keywords: scene recognition, aftereffects, global property, natural images, gist DOI: 10.1037/a0019058

The cost of attending to a visual event can be the failure to consciously detect other events. This processing limitation is well illustrated by the attentional blink paradigm, in which searching for and attending to a target presented in a rapid serial visual presentation stream of distractors can impair one's ability to detect a second target presented soon thereafter. The attentional blink critically depends on 'top-down' attentional settings, for it does not occur if participants are asked to ignore the first target. Here we show that 'bottom-up' attention can also lead to a profound but ephemeral deficit in conscious perception: Presentation of a novel, unexpected, and task-irrelevant stimulus virtually abolishes conscious detection of a target presented within half a second after the 'Surprise' stimulus, but only for its earliest occurrences (generally 1 to 2 presentations). This powerful but short-lived deficit contrasts with a milder but more enduring form of attentional capture that accompanies singleton presentations in rapid serial visual presentations. We conclude that the capture of stimulus-driven attention alone can limit explicit perception. Keywords: attention, orienting response, attentional blink, stimulus-driven DOI: 10.1037/a0020551

In a contextual cuing paradigm, we examined how memory for the spatial structure of a natural scene guides visual search. Participants searched through arrays of objects that were embedded within depictions of real-world scenes. If a repeated search array was associated with a single scene during study, then array repetition produced significant contextual cuing. However, expression of that learning was dependent on instantiating the original scene in which the learning occurred: Contextual cuing was disrupted when the repeated array was transferred to a different scene. Such scene-specific learning was not absolute, however. Under conditions of high scene variability, repeated search array were learned independently of the scene background. These data suggest that when a consistent environmental structure is available, spatial representations supporting visual search are organized hierarchically, with memory for functional subregions of an environment nested within a representation of the larger scene. Keywords: scene perception, visual search, visual memory, spatial memory, contextual cuing DOI: 10.1037/a0019257

Visual search efficiency improves by presenting (previewing) one set of distractors before the target and remaining distractor items (D. G. Watson & G. W. Humphreys, 1997). Previous work has shown that this preview benefit is abolished if the old items change their shape when the new items are added (e.g., D. G. Watson & G. W. Humphreys, 2002). Here we present 5 experiments that examined whether such object changes are still effective in recapturing attention if the changes occur while the previewed objects are occluded or masked. Overall, the findings suggest that masking transients are effective in preventing both object changes and the presentation of new objects from capturing attention in time-based visual search conditions. The findings are discussed in relation to theories of change blindness, new object capture, and the ecological properties of time-based visual selection. Keywords: visual marking, visual search, change blindness, attentional capture, luminance change DOI: 10.1037/a0020565

The human visual system is constantly confronted with an overwhelming amount of information, only a subset of which can be processed in complete detail. Attention and implicit learning are two important mechanisms that optimize vision. This study addressed the relationship between these two mechanisms. Specifically we asked, Is implicit learning of spatial context affected by the amount of working memory load devoted to an irrelevant task? We tested observers in visual search tasks where search displays occasionally repeated. Observers became faster when searching repeated displays than unrepeated ones, showing contextual cuing. We found that the size of contextual cuing was unaffected by whether observers learned repeated displays under unitary attention or when their attention was divided using working memory manipulations. These results held when working memory was loaded by colors, dot patterns, individual dot locations, or multiple potential targets. We conclude that spatial context learning is robust to interference from manipulations that limit the availability of attention and working memory. Keywords: contextual cuing, divided attention, visual search, visual working memory, implicit learning DOI: 10.1037/a0020558

The optic tectum of zebrafish is involved in behavioral responses that require the detection of small objects. The superficial layers of the tectal neuropil receive input from retinal axons, while its deeper layers convey the processed information to premotor areas. Imaging with a genetically encoded calcium indicator revealed that the deep layers, as well as the dendrites of single tectal neurons, are preferentially activated by small visual stimuli. This spatial filtering relies on GABAergic interneurons (using the neurotransmitter [gamma]-aminobutyric acid) that are located in the superficial input layer and respond only to large visual stimuli. Photo-ablation of these cells with KillerRed, or silencing of their synaptic transmission, eliminates the size tuning of deeper layers and impairs the capture of prey. 10.1126/science.1192949

Daily life continually confronts us with an exuberance of external, sensory stimuli competing with a rich stream of internal deliberations, plans and ruminations. The brain must select one or more of these for further processing. How this competition is resolved across multiple sensory and cognitive regions is not known; nor is it clear how internal thoughts and attention regulate this competition (1-4). Recording from single neurons in patients implanted with intracranial electrodes for clinical reasons (5-9), here we demonstrate that humans can regulate the activity of their neurons in the medial temporal lobe (MTL) to alter the outcome of the contest between external images and their internal representation. Subjects looked at a hybrid superposition of two images representing familiar individuals, landmarks, objects or animals and had to enhance one image at the expense of the other, competing one. Simultaneously, the spiking activity of their MTL neurons in different subregions and hemispheres was decoded in real time to control the content of the hybrid. Subjects reliably regulated, often on the first trial, the firing rate of their neurons, increasing the rate of some while simultaneously decreasing the rate of others. They did so by focusing onto one image, which gradually became clearer on the computer screen in front of their eyes, and thereby overriding sensory input. On the basis of the firing of these MTL neurons, the dynamics of the competition between visual images in the subject's mind was visualized on an external display., One can direct one's thoughts via external stimuli or internal imagination. Decades of single-neuron electrophysiology and functional brain imaging have revealed the neurophysiology of the visual pathway (1,2). When images [...]

The purpose of this study is to examine the effects of various levels of alcohol consumption on human response to auditory and visual stimuli in terms of reaction time, movement time, total reaction time, and error rate. Placebo level and three low-level alcohol doses were randomly assigned to 20 male university student volunteers. 30 min. after consuming the alcohol or placebo, participants responded to either auditory or visual stimuli. Total reaction time increased significantly at the mid-low dose of alcohol (0.3 g/kg). For alcohol doses less than .5 g/kg, the change in total reaction time was confined to reaction time, i.e., the processing time between onset of stimulus and onset of movement. Effects of alcohol were significantly more pronounced in the choice-type tests. Notably, the effects of alcohol on total reaction time and error rate were significant for auditory but not visual stimuli. DOI 10.2466/13.15.18.22.PMS.111.5.589-607

When something unique is present in a scene, this element may become immediately visible and one has the impression that it pops out from the scene. This phenomenon, known as pop-out in the visual search literature, is thought to produce the fastest search possible, and response times for the detection of the pop-out target do not vary as a function of the number of nontargets. In this study, we challenge this notion and show that the detection of a given visual feature is faster for multiple targets than for a single pop-out target. However, when the task requires a detailed target analysis, the pop-out condition can be faster than the multiple-target condition. Current models of visual search are discussed in light of the findings. Keywords: attention, pop-out, visual search DOI: 10.1037/a0019960

An important effect of sustained attention is the facilitation of perception. Although the term 'sustained' suggests that this beneficial effect endures continuously as long as something is attended, we present electrophysiological evidence that perception at attended locations is actually modulated periodically. Subjects detected brief light flashes that were presented peripherally at locations that were either attended or unattended. We analyzed the correlation between detection performance for attended and unattended stimuli and the phase of ongoing EEG oscillations, which relate to subsecond fluctuations of neuronal excitability. Although on average, detection performance was improved by attention--indicated by reduced detection thresholds at attended locations--we found that detection performance for attended stimuli actually fluctuated over time along with the phase of spontaneous oscillations in the 0 ([approximately equal to] 7 Hz) frequency band just before stimulus onset. This fluctuation was absent for unattended stimuli. This pattern of results suggests that 'sustained' attention in fact exerts its facilitative effect on perception in a periodic fashion. www.pnas.org/cgi/doi/10.1073/pnas.1004801107

We investigated whether young and older adults differ on measures of interference (INT), negative priming (NP), and inhibition of return (IOR) on a spatial selective attention task that gradually increased in cognitive demand, from simple perceptual matching to letter identification. For both groups, INT increased and IOR decreased with task demand; while NP remained stable. We round age-related increases in INT, NP, and IOR, independent of task demand. However, only between-groups differences in IOR remained after correcting for age-related slowing in response times. Finally, we found no association between our measures of attention across groups, suggesting negligible overlap between INT, NP, and IOR. Our results indicate that attention is selectively and independently influenced by age and task demands, with both effects dependent on how attention is measured. These findings shed light on the 'frontal hypothesis of aging.' Keywords: attention, aging, task complexity DOI: 10.1037/a0020650

To examine whether interhemispheric transfer during foveal word recognition entails a discontinuity between the information presented to the left and right of fixation, we presented target words in such a way that participants fixated immediately left or right of an embedded word (as in [gr.sup.*] apple, [bull.sup.*] et) or in the middle of an embedded word ([grapp.sup.*] le, [bu.sup.*] llet). Categorization responses to target words were faster and more accurate in a congruent condition (in which the embedded word was associated with the same response; e.g., Does bullet refer to an item of clothing?) than in an incongruent condition (e.g., Does bullet refer to a type of animal?). However. the magnitude of this effect did not vary as a function of position of fixation, relative to the embedded word, as might be expected if information from the 2 visual fields was initially split over the cerebral hemispheres and integrated only late in the word identification process. Equivalent results were observed in Experiment 1 (long stimulus duration) and Experiment 2 (in which stimulus duration was 200 ms: i.e., less than the time required to initiate a refixation). Keywords: split fovea, embedded word recognition, semantic categorization DOI: 10.1037/a0020224

Schizophrenia is characterized by impaired visual contrast sensitivity and anomalous perceptual experiences. The aim of this study was to investigate these phenomena in unmedicated patients with first-episode schizophrenia. Visual contrast sensitivity was measured with pulsed-pedestal and steady-pedestal tests, which bias information processing toward the parvocellular and magnocellular pathways, respectively. Anomalous perceptual experiences were investigated with the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that patients with schizophrenia (n = 20) exhibited increased contrast sensitivity values on the magnocellular test relative to the control participants (n = 20). In the parvocellular condition, there was no significant difference between the two groups. The higher magnocellular contrast sensitivity values were associated with increased visual SIAPA scores, especially at the two lowest spatial frequencies (0.25 and 0.5 cycles/degree). These results indicate the heightened sensitivity of magnocellular pathways in unmedicated first-episode schizophrenia, which may contribute to anomalous perceptual experiences and sensory overloading. Keywords: schizophrenia, first episode, contrast sensitivity, magnocellular pathways, vision DOI: 10.1037/a0019610

We addressed the question of how we locate and identify objects in complex natural environments by simultaneously recording single neurons from two brain regions that play different roles in this familiar activity--the frontal eye field (FEF), an area in the prefrontal cortex that is involved in visual spatial selection, and the inferotemporal cortex (IT), which is involved in object recognition--in monkeys performing a covert visual search task. Although the monkeys reported object identity, not location, neural activity specifying target location was evident in FEF before neural activity specifying target identity in IT. These two distinct processes were temporally correlated implying a functional linkage between the end stages of 'where' and 'what' visual processing and indicating that spatial selection is necessary for the formation of complex object representations associated with visual perception. attention | cognition | object recognition | perception doi/ 10.1073/pnas.1002870107

The purpose of this study was to examine variables that may contribute to shot accuracy in women's college lacrosse. A convenience sample of 15 healthy women's National Collegiate Athletic Association Division III College lacrosse players aged 18-23 (mean [+ or -] SD, 20.27 [+ or -] 1.67) participated in the study. Four experimental variables were examined: balance, visual search, hand grip strength, and shoulder joint position sense. Balance was measured by the Biodex Stability System (BSS), and visual search was measured by the Trail-Making Test Part A (TMTA) and Trail-Making Test Part B (TMTB). Hand-grip strength was measured by a standard hand dynamometer, and shoulder joint position sense was measured using a modified inclinometer. All measures were taken in an indoor setting. These experimental variables were then compared with lacrosse-shot error that was measured indoors using a high-speed video camera recorder and a specialized L-shaped apparatus. A Stalker radar gun measured lacrosse-shot velocity. The mean lacrosse-shot error was 15.17 cm with a mean lacrosse-shot velocity of 17.14 m x [s.sup.-1] (38.35 mph). Lower scores on the BSS level 8 eyes open (BSS L8 E/O) test and TMTB were positively related to less lacrosse-shot error (r = 0.760, p = 0.011) and (r = 0.519, p = 0.048), respectively. Relations were not significant between lacrosse-shot error and grip strength (r = 0.191, p = 0.496), lacrosse-shot error and BSS level 8 eyes closed (BSS L8 E/C) (r = 0.501, p = 0.102), lacrosse-shot error and BSS level 4 eyes open (BSS L4 E/O) (r = 0.313, p = 0.378), lacrosse-shot error and BSS level 4 eyes closed (BSS L4 E/C) (r = -0.029, p = 0.936) lacrosse-shot error and shoulder joint position sense (r= -0.509, p = 0.055) and between lacrosse-shot error and TMTA (r = 0.375, p = 0.168). The results reveal that greater levels of shot accuracy may be related to greater levels of visual search and balance ability in women college lacrosse athletes. KEY WORDS attention, athletic performance, cognition, eye gaze

The first aim of this study was to investigate how visual and somatosensory information influence bandstand performance according to the expertise level of gymnasts. The second aim was to determine whether the general perceptual characteristics of gymnasts are linked with their handstand performances. In the first experiment, expert and nonexpert gymnasts performed a handstand on a force platform in 4 conditions: open or closed eyes on a firm or foam support. To assess the gymnasts' performance, the surface area ([mm.sup.2]) covered by the trajectory of the center of pressure (COP) was recorded. The results showed that (a) experts had significantly (p < 0.05) better postural performance during the handstand than did nonexperts, whatever the visual condition, (b) nonexperts were unable to maintain the bandstand without vision, whatever the support, and (c) the CoP surface was significantly greater on the foam surface than on the firm surface for both experts and nonexperts and, only for experts, whatever the visual condition. In the second experiment, the gymnasts' general perceptual characteristics (field dependence-independence) were evaluated using the rod-and-frame test (RFT). Experts were less field dependent than nonexperts, and the RFT results were positively correlated with postural performance. We thus suggest that, although they did not cope more efficiently with the somatosensory perturbation, expert gymnasts had developed a capacity to use the remaining sensory modalities efficiently when vision was removed. Also, a high level of gymnastics training may improve the ability to change the frame of reference. For the bandstand, exercises alternating the use of visual and nonvisual information could be an interesting technique for trainers to improve gymnasts' performance. KEY WORDS handstand, postural performance, sensory information, rod-and-frame test, training

Linguistic categories have been shown to influence perceptual discrimination, to do so preferentially in the right visual field, to fail to do so when competing demands are made on verbal memory, and to vary with the color-term boundaries of different languages. However, because there are strong commonalities across languages in the placement of color-term boundaries, the question remains open whether observed categorical perception for color can be entirely a result of learned categories or may rely to some degree on innate ones. We show here that lateralized color categorical perception can be entirely the result of learned categories. In a visual search task, reaction times to targets were faster in the right than the left visual field when the target and distractor colors, initially sharing the same linguistic term (e.g., 'blue'), became between-category colors after training (i.e., when two different shades of blue had each acquired a new name). A control group, whose conditions exactly matched those of the experimental group except that no new categories were introduced, did not show this effect, establishing that the effect was not dependent on increased familiarity with either the color stimuli or the task. The present results show beyond question that lateralized categorical perception of color can reflect strictly learned color categories, even artificially learned categories that violate both universal tendencies in color naming and the categorization pattern of the language of the subject. category learning | Whorf hypothesis | nature versus nurture | linguistic relativity doi/ 10.1073/pnas.1005669107

Two experiments were conducted to assess the effects of verbal interference on categorical perception. The task involved simultaneous color discrimination with no memory demands, and a concurrent Stroop task was employed as verbal interference. Exp. I demonstrated that categorical perception was eliminated by an incongruent color word (i.e., Stroop interference), but not by a congruent color word or nonword fixation crosses. Exp. 2 demonstrated that categorical perception decreased when the intensity of Stroop Interference was increased, and it increased when correct verbal coding was enhanced. These results provide further evidence that interfering with verbal coding disrupts categorical perception, suggesting that verbal coding has a crucial role in categorical 'perception.' It is also suggested that categorical perception could occur at the encoding or decision level but not at the storage or memory level. The possible mechanisms for categorical perception are also discussed. DOI 10.2466/PMS. 110.3.857-878

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apergo.2009.10.002 Byline: AnaA[macron]s Mayeur (a)(b), Roland Bremond (a), J.M. Christian Bastien (c) Abstract: The Small Target Visibility (STV) model is the main model used to assess the quality of road lighting installations (). However, this model is based on a simple detection task in foveal vision using psychophysical data from laboratory conditions. The purpose of this study was to evaluate the impact of a complex background and apparent motion on target detection performance in mesopic vision, for three luminance contrasts, with reference to the STV scenario. To do so, participants were invited to detect standard square targets varying in terms of contrast presented in three Conditions: a uniform background, still images, and a video. Luminance levels were chosen in the mesopic domain relevant for road lighting at night. Images and video were chosen in relation to a driving task at night. The results showed that both the spatial context and the apparent motion had a negative impact on peripheral target detection performance: contrasts which are easy to detect in conditions close to the STV reference data may lead to poor performance if one adds context variables. These results give evidence that the STV model used for road lighting design based on laboratory data is limited, which strengthens previous results (). The results are discussed in relation to the field factor used by practitioners to compensate for the differences between the STV reference scenario (detection of a small square target on a lit road while driving) and the STV psychophysical reference data. Author Affiliation: (a) Universite Paris Est, LEPSiS, INRETS-LCPC, Paris, France (b) Universite Paris Descartes, ECI, Paris, France (c) Universite Paul Verlaine, ETIC, Metz, France Article History: Received 3 March 2009; Accepted 5 October 2009

In the past 20 years, numerous theories and findings have suggested that the unit of visual attention is the object. In this study, 1 first clarity 2 different meanings of unit of visual attention, namely the unit of access in the sense of measurement and the unit of selection in the sense of division. In accordance with this distinction, I argue that an object, as commonly described, is only the unit of selection. The unit of access is better characterized as a Boolean map (Huang & Pashler. 2007), that is, the linkage of a single feature value per dimension associated with a map (i.e., a set of locations). The experiments in this study demonstrated the following: (a) Grouping items into a single object (by connecting them) does not improve the perception of these items (Experiment 1): (b) same-object advantage exists only when the features to be perceived are different dimensions of a single Boolean map and not when they belong to different parts of an object (Experiments 2 and 3); (c) cuing the relevant feature does not help perception when the features to be perceived are different dimensions of a single Boolean map but does help significantly when these features belong to different parts of an object (Experiment 4); and (d) connection, as used in Experiments 1-4, is effective in affecting object structure (i.e., affecting the mechanism of selection) in both an enumeration and a tracking task (Experiments 5 and 6). The results of these experiments, together with data available in the literature, demonstrate that the unit of access is a Boolean map, not an object. Keywords: visual attention, Boolean map, object, object-based attention DOI: 10.1037/a0018034

A tight correspondence has been postulated between the representations of number and space. The spatial numerical association of response codes (SNARC) effect, which reflects the observation that people respond faster with the left-hand side to small numbers and with the right-hand side to large numbers, is regarded as strong evidence for this correspondence. The dominant explanation of the SNARC effect is that it results from visuospatial coding of magnitude (e.g., the mental number line hypothesis). In a series of experiments, we demonstrated that this is only part of the story and that verbal-spatial coding influences processes and representations that have been believed to be purely visuospatial. Additionally, when both accounts were directly contrasted, verbal-spatial coding was observed in absence of visuospatial coding. Relations to other number-space interactions and implications for other tasks are discussed. Keywords: SNARC effect, numerical cognition DOI: 10.1037/a0017688