Perceiving social interactions in the posterior superior temporal sulcus

Primates are highly attuned not just to social characteristics of individual agents, but also to social interactions between multiple agents. Here we report a neural correlate of the representation of social interactions in the human brain. Specifically, we observe a strong univariate response in the posterior superior temporal sulcus (pSTS) to stimuli depicting social interactions between two agents, compared with (i) pairs of agents not interacting with each other, (ii) physical interactions between inanimate objects, and (iii) individual animate agents pursuing goals and interacting with inanimate objects. We further show that this region contains information about the nature of the social interaction - specifically, whether one agent is helping or hindering the other. This sensitivity to social interactions is strongest in a specific subregion of the pSTS but extends to a lesser extent into nearby regions previously implicated in theory of mind and dynamic face perception. This sensitivity to the presence and nature of social interactions is not easily explainable in terms of low-level visual features, attention, or the animacy, actions, or goals of individual agents. This region may underlie our ability to understand the structure of our social world and navigate within it.National Science Foundation (U.S.) (Grant CCF-1231216

What is the Bandwidth of Perceptual Experience?

Although our subjective impression is of a richly detailed visual world, numerous empirical results suggest that the amount of visual information observers can perceive and remember at any given moment is limited. How can our subjective impressions be reconciled with these objective observations? Here, we answer this question by arguing that, although we see more than the handful of objects, claimed by prominent models of visual attention and working memory, we still see far less than we think we do. Taken together, we argue that these considerations resolve the apparent conflict between our subjective impressions and empirical data on visual capacity, while also illuminating the nature of the representations underlying perceptual experience. Numerous empirical results highlight the limits of visual perception, attention, and working memory. However, it intuitively feels as though we have a rich perceptual experience, leading many to claim that conscious perception overflows these limited cognitive mechanisms.A relatively new field of study (visual ensembles and summary statistics) provides empirical support for the notion that perception is not limited and that observers have access to information across the entire visual world.Ensemble statistics, and scene processing in general, also appear to be supported by neural structures that are distinct from those supporting object perception. These distinct mechanisms can work partially in parallel, providing observers with a broad perceptual experience.Moreover, new demonstrations show that perception is not as rich as is intuitively believed. Thus, ensemble statistics appear to capture the entirety of perceptual experience.National Institutes of Health (U.S.). Ruth L. Kirschstein National Research Service Award (F32EY024483)National Institutes of Health (U.S.) (Grant EY13455

How fMRI Can Inform Cognitive Theories

How can functional magnetic resonance imaging (fMRI) advance cognitive theory? Some have argued that fMRI can do little beyond localizing brain regions that carry out certain cognitive functions (and may not even be able to do that). However, in this article, we argue that fMRI can inform theories of cognition by helping to answer at least four distinct kinds of questions. Which mental functions are performed in brain regions specialized for just that function (and which are performed in more general-purpose brain machinery)? When fMRI markers of a particular Mental Process X are found, is Mental Process X engaged when people perform Task Y? How distinct are the representations of different stimulus classes? Do specific pairs of tasks engage common or distinct processing mechanisms? Thus, fMRI data can be used to address theoretical debates that have nothing to do with where in the brain a particular process is carried out

Color-Biased Regions of the Ventral Visual Pathway Lie between Face- and Place-Selective Regions in Humans, as in Macaques

The existence of color-processing regions in the human ventral visual pathway (VVP) has long been known from patient and imaging studies, but their location in the cortex relative to other regions, their selectivity for color compared with other properties (shape and object category), and their relationship to color-processing regions found in nonhuman primates remain unclear. We addressed these questions by scanning 13 subjects with fMRI while they viewed two versions of movie clips (colored, achromatic) of five different object classes (faces, scenes, bodies, objects, scrambled objects). We identified regions in each subject that were selective for color, faces, places, and object shape, and measured responses within these regions to the 10 conditions in independently acquired data. We report two key findings. First, the three previously reported color-biased regions (located within a band running posterior–anterior along the VVP, present in most of our subjects) were sandwiched between face-selective cortex and place-selective cortex, forming parallel bands of face, color, and place selectivity that tracked the fusiform gyrus/collateral sulcus. Second, the posterior color-biased regions showed little or no selectivity for object shape or for particular stimulus categories and showed no interaction of color preference with stimulus category, suggesting that they code color independently of shape or stimulus category; moreover, the shape-biased lateral occipital region showed no significant color bias. These observations mirror results in macaque inferior temporal cortex (Lafer-Sousa and Conway, 2013), and taken together, these results suggest a homology in which the entire tripartite face/color/place system of primates migrated onto the ventral surface in humans over the course of evolution.National Institutes of Health (U.S.) (Grant EY13455)National Institutes of Health (U.S.) (Grant EY023322)National Institutes of Health (U.S.) (Grant 5T32GM007484-38)National Science Foundation (U.S.) (STC Award CCF-1231216)National Science Foundation (U.S.) (Grant 1353571)National Science Foundation (U.S.). Graduate Research Fellowshi

Multivariate Patterns in Object-Selective Cortex Dissociate Perceptual and Physical Shape Similarity

Prior research has identified the lateral occipital complex (LOC) as a critical cortical region for the representation of object shape in humans. However, little is known about the nature of the representations contained in the LOC and their relationship to the perceptual experience of shape. We used human functional MRI to measure the physical, behavioral, and neural similarity between pairs of novel shapes to ask whether the representations of shape contained in subregions of the LOC more closely reflect the physical stimuli themselves, or the perceptual experience of those stimuli. Perceptual similarity measures for each pair of shapes were obtained from a psychophysical same-different task; physical similarity measures were based on stimulus parameters; and neural similarity measures were obtained from multivoxel pattern analysis methods applied to anterior LOC (pFs) and posterior LOC (LO). We found that the pattern of pairwise shape similarities in LO most closely matched physical shape similarities, whereas shape similarities in pFs most closely matched perceptual shape similarities. Further, shape representations were similar across participants in LO but highly variable across participants in pFs. Together, these findings indicate that activation patterns in subregions of object-selective cortex encode objects according to a hierarchy, with stimulus-based representations in posterior regions and subjective and observer-specific representations in anterior regions

Feature-Binding Errors After Eye Movements and Shifts of Attention

When people move their eyes, the eye-centered (retinotopic) locations of objects must be updated to maintain world-centered (spatiotopic) stability. Here, we demonstrated that the attentional-updating process temporarily distorts the fundamental ability to bind object locations with their features. Subjects were simultaneously presented with four colors after a saccade—one in a precued spatiotopic target location—and were instructed to report the target’s color using a color wheel. Subjects’ reports were systematically shifted in color space toward the color of the distractor in the retinotopic location of the cue. Probabilistic modeling exposed both crude swapping errors and subtler feature mixing (as if the retinotopic color had blended into the spatiotopic percept). Additional experiments conducted without saccades revealed that the two types of errors stemmed from different attentional mechanisms (attention shifting vs. splitting). Feature mixing not only reflects a new perceptual phenomenon, but also provides novel insight into how attention is remapped across saccades.National Institutes of Health (U.S.) (Grant R01-EY13455

Discovering Structure in the Space of fMRI Selectivity Profiles

We present a method for discovering patterns of selectivity in fMRI data for experiments with multiple stimuli/tasks. We introduce a representation of the data as profiles of selectivity using linear regression estimates, and employ mixture model density estimation to identify functional systems with distinct types of selectivity. The method characterizes these systems by their selectivity patterns and spatial maps, both estimated simultaneously via the EM algorithm. We demonstrate a corresponding method for group analysis that avoids the need for spatial correspondence among subjects. Consistency of the selectivity profiles across subjects provides a way to assess the validity of the discovered systems. We validate this model in the context of category selectivity in visual cortex, demonstrating good agreement with the findings based on prior hypothesis-driven methods.McGovern Institute Neurotechnology (MINT) ProgramNational Institutes of Health (U.S.) (Grant NIBIB NAMIC U54-EB005149)National Institutes of Health (U.S.) (Grant NCRR NAC P41-RR13218)National Eye Institute (grant 13455)National Science Foundation (U.S.) (grant CAREER 0642971)Collaborative Research in Computational Neuroscience (IIS/CRCNS 0904625)Deshpande Center for Technological Innovation (MIT HST Catalyst grant)American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

Multiple Object Tracking in Autism Spectrum Disorders

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.Ellison Medical FoundationSimons Foundatio

Global/Local Processing in Autism: Not a Disability, but a Disinclination

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.Ellison Medical FoundationSimons Foundatio