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It is widely suggested that ASD is characterized by atypical local/global processing, but the published findings are contradictory. In an effort to resolve this question, we tested a large group of children on both a free-choice task and an instructed task using hierarchical local-global stimuli. We find that although children with autism showed a reduced preference to report global properties of a stimulus when given a choice, their ability to process global properties when instructed to do so is unimpaired. These findings support prior claims that people with ASD show a disinclination, not a disability, in global processing, and highlight the broader question of whether other characteristics of autism may also reflect disinclinations rather than disabilities. Keywords Autism spectrum disorder * Global/local processing * Global attention * Cognitive development, Introduction Extensive research has investigated the hypothesis that people with autism differ from typical individuals in their processing of global versus local information, but the precise nature and even the [...]

Difficulties in visual attention are often implicated in autism spectrum disorders (ASD) but it remains unclear which aspects of attention are affected. Here, we used a multiple object tracking (MOT) task to quantitatively characterize dynamic attentional function in children with ASD aged 5-12. While the ASD group performed significantly worse overall, the group difference did not increase with increased object speed. This finding suggests that decreased MOT performance is not due to deficits in dynamic attention but instead to a diminished capacity to select and maintain attention on multiple targets. Further, MOT performance improved from 5 to 10 years in both typical and ASD groups with similar developmental trajectories. These results argue against a specific deficit in dynamic attention in ASD. Keywords Autism spectrum disorder * Multiple object tracking * Dynamic attention * Spatial attention * Cognitive development, Introduction Visual attention serves as a fundamental filter of experience, selecting a small subset of the incoming sensory information for further processing. Attention thus determines what we perceive, remember, and [...]

Ending violent international conflicts requires understanding the causal factors that perpetuate them. In the Israeli--Palestinian conflict, Israelis and Palestinians each tend to see themselves as victims, engaging in violence only in response to attacks initiated by a fundamentally and implacably violent foe bent on their destruction. Econometric techniques allow us to empirically test the degree to which violence on each side occurs in response to aggression by the other side. Prior studies using these methods have argued that Israel reacts strongly to attacks by Palestinians, whereas Palestinian violence is random (i.e., not predicted by prior Israeli attacks). Here we replicate prior findings that Israeli killings of Palestinians increase after Palestinian killings of Israelis, but crucially show further that when nonlethal forms of violence are considered, and when a larger dataset is used, Palestinian violence also reveals a pattern of retaliation: (i) the firing of Palestinian rockets increases sharply after Israelis kill Palestinians, and (ii) the probability (although not the number) of killings of Israelis by Palestinians increases after killings of Palestinians by Israel. These findings suggest that Israeli military actions against Palestinians lead to escalation rather than incapacitation. Further, they refute the view that Palestinians are uncontingently violent, showing instead that a significant proportion of Palestinian violence occurs in response to Israeli behavior. Well-established cognitive biases may lead participants on each side of the conflict to underappreciate the degree to which the other side's violence is retaliatory, and hence to systematically underestimate their own role in perpetuating the conflict. doi/ 10.1073/pnas.1012115107

Is the human mind/brain composed of a set of highly specialized components, each carrying out a specific aspect of human cognition, or is it more of a general-purpose device, in which each component participates in a wide variety of cognitive processes? For nearly two centuries, proponents of specialized organs or modules of the mind and brain--from the phrenologists to Broca to Chomsky and Fodor--have jousted with the proponents of distributed cognitive and neural processing--from Flourens to Lashley to McClelland and Rumelhart. I argue here that research using functional MRI is beginning to answer this long-standing question with new clarity and precision by indicating that at least a few specific aspects of cognition are implemented in brain regions that are highly specialized for that process alone. Cortical regions have been identified that are specialized not only for basic sensory and motor processes but also for the high-level perceptual analysis of faces, places, bodies, visually presented words, and even for the very abstract cognitive function of thinking about another person's thoughts. I further consider the as-yet unanswered questions of how much of the mind and brain are made up of these functionally specialized components and how they arise developmentally. brain imaging | modularity | functional MRI | fusiform face area doi/ 10.1073/pnas.1005062107

The biased-competition theory accounts for attentional effects at the single-neuron level: It predicts that the neuronal response to simultaneously-presented stimuli is a weighted average of the response to isolated stimuli, and that attention biases the weights in favor of the attended stimulus. Perception, however, relies not on single neurons but on larger neuronal populations. The responses of such populations are in part reflected in large-scale multivoxel fMRI activation patterns. Because the pooling of neuronal responses into blood-oxygen-level-dependent signals is non-linear, fMRI effects of attention need not mirror those observed at the neuronal level. Thus, to bridge the gap between neuronal responses and human perception, it is fundamental to understand attentional influences in large-scale multivariate representations of simultaneously-presented objects. Here, we ask how responses to simultaneous stimuli are combined in multivoxel fMRI patterns, and how attention affects the paired response. Objects from four categories were presented singly, or in pairs such that each category was attended, unattended, or attention was divided between the two. In a multidimensional voxel space, the response to simultaneously-presented categories was well described as a weighted average. The weights were biased toward the preferred category in category-selective regions. Consistent with single-unit reports, attention shifted the weights by [approximately equal to]30% in favor of the attended stimulus. These findings extend the biased-competition framework to the realm of large-scale multivoxel brain activations. pattern classification | fMRI | response combination | ventral temporal cortex doi/ 10.1073/pnas.0907330106

Theories of probabilistic cognition postulate that internal representations are made up of multiple simultaneously held hypotheses, each with its own probability of being correct (henceforth, 'probability distributions'). However, subjects make discrete responses and report the phenomenal contents of their mind to be all-or-none states rather than graded probabilities. How can these 2 positions be reconciled? Selective attention tasks, such as those used to study crowding, the attentional blink, rapid serial visual presentation, and so forth, were recast as probabilistic inference problems and used to assess how graded, probabilistic representations may produce discrete subjective states. The authors asked subjects to make multiple guesses per trial and used 2nd-order statistics to show that (a) visual selective attention operates in a graded fashion in time and space, selecting multiple targets to varying degrees on any given trial; and (b) responses are generated by a process of sampling from the probabilistic states that result from graded selection. The authors concluded that although people represent probability distributions, their discrete responses and conscious states are products of a process that samples from these probabilistic representations. Keywords: attention, cognition, probabilistic inference DOI: 10.1037/a0017352

Since Ungerleider and Mishkin [Underleider LG, Mishkin M (1982) Two cortical visual systems. Analysis of Visual Behavior, eds Ingle MA, Goodale MI, Masfield RJW (MIT Press, Cambridge, MA), pp 549-586] proposed separate visual pathways for processing object shape and location, steady progress has been made in characterizing the organization of the two kinds of information in extrastriate visual cortex in humans. However, to date, there has been no broad-based survey of category and location information across all major functionally defined object-selective regions. In this study, we used an fMRI region-of-interest (ROI) approach to identify eight regions characterized by their strong selectivity for particular object categories (faces, scenes, bodies, and objects). Participants viewed four types of stimuli (faces, scenes, bodies, and cars) appearing in each of three different spatial locations (above, below, or at fixation). Analyses based on the mean response and voxelwise patterns of response in each ROI reveal location information in almost all of the known object-selective regions. Furthermore, category and location information can be read out independently of one another such that most regions contain both position-invariant category information and category-invariant position information. Finally, we find substantially more location information in ROIs on the lateral than those on the ventral surface of the brain, even though these regions have equal amounts of category information. Although the presence of both location and category information in most object-selective regions argues against a strict physical separation of processing streams for object shape and location, the ability to extract position-invariant category information and category-invariant position information from the same neural population indicates that form and location information nonetheless remain functionally independent. fusiform face area | position invariance | parahippocampal place area

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-9280.2008.02046.x Byline: Edward Vul (1), Mark Nieuwenstein (1), Nancy Kanwisher (1) Abstract: ABSTRACT How does temporal selection work, and along what dimensions does it vary from one instance to the next? We explored these questions using a phenomenon in which temporal selection goes awry. In the attentional blink, subjects fail to report the second of a pair of targets (T1 and T2) when they are presented at stimulus onset asynchronies (SOAs) of roughly 200 to 500 ms. We directly tested the properties of temporal selection during the blink by analyzing distractor intrusions at a fast rate of item presentation. Our analysis shows that attentional selection is (a) suppressed, (b) delayed, and (c) diffused in time during the attentional blink. These effects are dissociated by their time course: The measure of each effect returns to the baseline value at a different SOA. Our results constrain theories of the attentional blink and indicate that temporal selection varies along at least three dissociable dimensions: efficacy, latency, and precision. Author Affiliation: (1)Department of Brain and Cognitive Science, Massachusetts Institute of Technology Article History: (R eceived 3/2/07; R evision accepted 6/9/07) Article note: Mark Nieuwenstein is now at the Department of Cognitive Psychology, Vrije Universiteit, Amsterdam, The Netherlands. Address correspondence to Edward Vul, Department of Brain and Cognitive Science, Massachusetts Institute of Technology, 77 Massachusetts Ave. 46-4141, Cambridge, MA 02139, e-mail: evul@mit.edu.

How do category-selective regions arise in human extrastriate cortex? Visually presented words provide an ideal test of the role of experience: Although individuals have extensive experience with visual words, our species has only been reading for a few thousand years, a period not thought to be long enough for natural selection to produce a genetically specified mechanism dedicated to visual word recognition per se. Using relatively high-resolution functional magnetic resonance imaging (1.4 x 1.4 x 2-mm voxels), we identified a small region of extrastriate cortex in most participants that responds selectively to both visually presented words and consonant strings, compared with line drawings, digit strings, and Chinese characters. Critically, we show that this pattern of selectivity is dependent on experience with specific orthographies: The same region responds more strongly to Hebrew words in Hebrew readers than in nonreaders of Hebrew. These results indicate that extensive experience with a given visual category can produce strong selectivity for that category in discrete cortical regions. learning | vision | fMRI | experience | ventral visual pathway

Functional magnetic resonance imaging (fMRI) was used to test predictions of the object-based theory that pre-attentive mechanisms section the visual array into objects, groups or surfaces, which act as visual attentional targets. Attending to one attribute of an object was found to enhance the neural representation of the attributed, and also of the other attribute of the same object.

It has been established that there is a region of parahippocampal cortex that responds selectively to visual scenes showing places. Activation in this region takes place automatically even when no explicit cognitive test is needed. The region, named the parahippocampal place area, only responds weakly to single objects and not at all to faces. It is suggested that this region represents places by encoding the geometry of the local environment.

Positron emission tomography (PET) was used to locate an area in human extrastriate cortex that subserves a specific component process of visual object recognition. Regional blood flow increased in a bilateral extrastriate area on the inferolateral surface of the brain near the border between the occipital and temporal lobes (and a smaller area in the right fusiform gyrus) when subjects viewed line drawings of 3-dimensional objects compared to viewing scrambled drawings with no clear shape interpretation. Responses were seen for both novel and familiar objects, implicating this area in the bottom-up (i.e., memory-independent) analysis of visual shape., INTRODUCTION Although neurophysiological studies over the last 25 years have provided a richly detailed map of the 30 or more different visual areas of the macaque brain (Felleman & Van [...]

Selective attention to color or shape minimizes spatial repetition blindness, as selecting the color of one object and the shape of another simultaneous object results in the access of both dimensions for both objects. Results of three follow-up studies confirmed that performance is only affected by repetition on both dimensions when the same dimension is judged for both stimuli, while performance is affected by repetition on both dimensions when different dimensions were judged for the two stimuli.

N. G. Kanwisher (1987; J. Park & N. G. Kanwisher, 1994) has explained repetition blindness in terms of a distinction in visual perception between type activation and token individuation; repeated items are successfully recognized (matched to stored types) but are less likely than unrepeated items to become individuated as separate perceptual tokens. Whittlesea and colleagues (B. W. A. Whittlesea, M. D. Dorken, & K. W. Podrouzek, 1995; B. W. A. Whittlesea & K. W. Podrouzek, 1995) argued that repetition blindness does not reflect different processing of repeated and unrepeated items but is better explained as the result of a combination of separate but nondistinctive processing of repeated items and postlist report biases. However, we argue that none of the results reported by Whittlesea and colleagues are inconsistent with the token-individuation hypothesis.

Negative priming (NP) is commonly thought to occur because distractor inhibition is necessary for target selection (the distractor inhibition hypothesis). Contrary to this account, the selection of a target in the preceding trial is shown to be neither necessary (Experiment 1) nor sufficient (Experiments 2 and 3) for NP in a target localization task modeled after S. P. Tipper, J. C. Brehaut, and J. Driver (1990). Experiments 4 and 5 provide further evidence against the distractor inhibition hypothesis and support an alternative mismatching account: NP in the spatial selection task apparently results from a change in the symbol bound to a given location (D. Kahneman, A. M. Treisman, & B. J. Gibbs, 1992), rather than a change in the status of that location from distractor to target (S. P. Tipper, J. C. Brehaut, & J. Driver, 1990).

Repetition blindness (RB) for letters presented in rapid serial visual presentation (RSVP) was shown to be highly dependent on absolute stimulus presentation rate (Experiment 1) and on the duration of the 2nd occurrence (C2) but not the 1st occurrence (C1) of the repeated item (Experiment 2). In Experiments 3-6, RB was strongly affected by C1-C2 interstimulus interval but not by response requirements or total memory load. In Experiment 7, sensitivity for detection of the 2nd vowel in an RSVP sequence of consonants was lower when it was identical to the 1st vowel (mean d prime = .40) than when it was different (mean d prime = .70). It is argued that RB is not due to (a) temporal overlap of C1 and C2 recognition, (b) forgetting of C2, (c) item-specific output interference, (d) response bias, or (e) guessing strategies; rather, RB arises because of the failure to bind recognized types to individuated tokens.

Repetition blindness (RB) is the failure to detect or recall repetitions of words in rapid serial visual presentation. Experiment 1 showed that synonym pairs are not susceptible to RB. In Experiments 2 and 3, RB was still found when one occurrence of the word was part of a compound noun phrase. In Experiment 4, homonyms produced RB if they were spelled identically (even if pronounced differently) but not if spelled differently and pronounced the same. Similarly spelled but otherwise unrelated word pairs appeared to generate RB (Experiment 5), but Experiment 6 produced an alternative account. Experiments 7 and 8 demonstrated that repeated letters are susceptible to RB only when displayed individually, not as part of two otherwise different words. It is concluded that RB can occur at either an orthographic (possibly morphemic) level or a case-independent letter level, depending on which unit (words or single letters) is the focus of processing.

What is the sequence of processing steps involved in visual object recognition? We varied the exposure duration of natural images and measured subjects' performance on three different tasks, each designed to tap a different candidate component process of object recognition. For each exposure duration, accuracy was lower and reaction time longer on a within-category identification task (e.g., distinguishing pigeons from other birds) than on a perceptual categorization task (e.g., birds vs. cars). However, strikingly, at each exposure duration, subjects performed just as quickly and accurately on the categorization task as they did on a task requiring only object detection: By the time subjects knew an image contained an object at all, they already knew its category. These findings place powerful constraints on theories of object recognition.

We used functional magnetic resonance imaging (fMRI) to investigate the psychological refractory period (PRP), the delay in the response to the second of two tasks occurring in immediate succession. Our results were consistent with prior work on the PRP in that when two visual-manual tasks were presented within 100 ms of each other, the second response was delayed on the order of 500 ms, compared with when the two tasks were separated by 1,500 ms. Surprisingly, in brain regions postulated to be important for executive functions, there was virtually no increase in brain activation in the short-interval compared with the long-interval condition. These data suggest that passive queuing, rather than active monitoring, occurs during the PRP.

This article examines the role of covert orienting of attention in response to channel activation. The authors, employing the flanker interference and precueing models in four experiments, conclude flanker interference proceeds at unattended locations and response channel activation can occur independently from spatial attention.

Despite extensive evidence for regions of human visual cortex that respond selectively to faces, few studies have considered the cortical representation of the appearance of the rest of the human body. We present a series of functional magnetic resonance imaging (fMRI) studies revealing substantial evidence for a distinct cortical region in humans that responds selectively to images of the human body, as compared with a wide range of control stimuli. This region was found in the lateral occipitotemporal cortex in all subjects tested and apparently reflects a specialized neural system for the visual perception of the human body., One of the most fundamental questions about visual object recognition in humans is whether all kinds of objects are processed by the same neural mechanisms, or whether instead some object [...]

The human lateral occipital complex (LOC) has been implicated in object recognition, but it is unknown whether this region represents low-level image features or perceived object shape. We used an event-related functional magnetic resonance imaging adaptation paradigm in which the response to pairs of successively presented stimuli is lower when they are identical than when they are different. Adaptation across a change between the two stimuli in a pair provides evidence for a common neural representation invariant to that change. We found adaptation in the LOC when perceived shape was identical but contours differed, but not when contours were identical but perceived shape differed. These data indicate that the LOC represents not simple image features, but rather higher level shape information., A central goal for any theory of human visual object recognition is to characterize the internal representations we extract from visually presented objects. Recent findings from neuroimaging in humans suggest [...]

Abstract * A still photograph of an object in motion may convey dynamic information about the position of the object immediately before and after the photograph was taken (implied motion). [...]

Repetition blindness (Kanwisher, 1986, 1987) is the failure to detect repetitions of words in lists presented in rapid serial visual presentation (RSVP). Two questions were investigated in the present study. First, if repetition blindness is not found with auditory presentation, it would support a specifically visual account of the effect. Second, if displacement of the two instances in visual space eliminates repetition blindness, it would suggest that repetition blindness is restricted to instances in which identical stimuli are distinguished solely by temporal differences. In Experiment 1, the subjects omitted second occurrences of repeated words in verbatim recall of rapid sentences presented visually (in RSVP), but not auditorily (using compressed speech), indicating that repetition blindness is a modality-specific phenomenon. In Experiments 2 and 3, repetition blindness was observed even when two occurrences of a written word were presented in different locations, showing that distinct locations do not guarantee token individuation. The results are discussed within a model that distinguishes between processes of type recognition and token individuation.

Seeing the world around you is like drinking from a firehose. The flood of information that enters the eyes could easily overwhelm the capacity of the visual system. To solve [...]