Object-centered Reference Frame Research Articles

Orientation and Experience in the Perception of Form: A Study with the Arizona Whale–Kangaroo

Abstract When subjects are presented with the Arizona whale–kangaroo, an ambiguous figure, perception of the whale is more common than perception of the kangaroo. However, this difference is smaller in Australian than American subjects. Perception of the kangaroo is more orientation dependent than perception of the whale, which is perceived at all orientations of the stimulus. Together with the difference between subject populations, this effect reveals an influence of past experience on the perception of this new ambiguous figure. Perception of the whale versus the kangaroo differs in both reconstrual of parts and realignment of the object-centered reference frame. Observers report reference frame reconstruals before reference frame reversals, shedding light on the organization of object memory.

Testing the role of response repetition in spatial priming in visual search.

In common "attention" tasks, which require stimulus-identity processing prior to the formation of a speeded key-press response, spatial priming effects depend on response repetition. Typically, the repetition of a stimulus location is advantageous when the prior response repeats, but disadvantageous or inconsequential when the prior response changes. This link between responding and space makes it difficult to draw inferences about attentional bias from two-choice key-press tasks. Instead, the findings are accounted for by episodic retrieval theories, which argue that the response associated with a prior stimulus location is retrieved when a later stimulus occupies its space. This retrieval operation is advantageous if the prior response is needed but not otherwise, which explains typical patterns. This perspective motivated us to evaluate whether spatial priming effects in the visual-search literature depend critically on response repetition. To assess this, we reevaluated a series of experiments recently published by Tower-Richardi, Leber, and Golomb (Attention, Perception, & Psychophysics, 78(1), 114-132, 2016). Their goal was to determine the reference frame of spatial priming across visual search displays. Reassessment reveals that spatial priming was strongly dependent on response repetition when spatiotopic, retinotopic, and object-centered reference frames were perfectly confounded. However, when eye movements were made to dissociate the spatiotopic and object-centered reference frame from the retinotopic reference frame, spatial priming was positive and unaffected by response repetition. The findings demonstrate that at least two distinct processes factor into spatial priming across visual searches, which occur at different levels of representation.

A neuroanatomical model of space-based and object-centered processing in spatial neglect

Visual attention can be deployed in space-based or object-centered reference frames. Right-hemisphere damage may lead to distinct deficits of space- or object-based processing, and such dissociations are thought to underlie the heterogeneous nature of spatial neglect. Previous studies have suggested that object-centered processing deficits (such as in copying, reading or line bisection) result from damage to retro-rolandic regions while impaired spatial exploration reflects damage to more anterior regions. However, this evidence is based on small samples and heterogeneous tasks. Here, we tested a theoretical model of neglect that takes in account the space- and object-based processing and relates them to neuroanatomical predictors. One hundred and one right-hemisphere-damaged patients were examined with classic neuropsychological tests and structural brain imaging. Relations between neglect measures and damage to the temporal-parietal junction, intraparietal cortex, insula and middle frontal gyrus were examined with two structural equation models by assuming that object-centered processing (involved in line bisection and single-word reading) and space-based processing (involved in cancelation tasks) either represented a unique latent variable or two distinct variables. Of these two models the latter had better explanatory power. Damage to the intraparietal sulcus was a significant predictor of object-centered, but not space-based processing, while damage to the temporal-parietal junction predicted space-based, but not object-centered processing. Space-based processing and object-centered processing were strongly intercorrelated, indicating that they rely on similar, albeit partly dissociated processes. These findings indicate that object-centered and space-based deficits in neglect are partly independent and result from superior parietal and inferior parietal damage, respectively.

Positional priming of visual pop-out search is supported by multiple spatial reference frames.

The present study investigates the representations(s) underlying positional priming of visual ‘pop-out’ search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions.

Perception of shape and space across rigid transformations

Objects in our environment are subject to manifold transformations, either of the physical objects themselves or of the object images on the retina. Despite drastic effects on the objects’ physical appearances, we are often able to identify stable objects across transformations and have strong subjective impressions of the transformations themselves. This suggests the brain is equipped with sophisticated mechanisms for inferring both object constancy, and objects’ causal history. We employed a dot-matching task to study in geometrical detail the effects of rigid transformations on representations of shape and space. We presented an untransformed ‘base shape’ on the left side of the screen and its transformed counterpart on the right (rotated, scaled, or both). On each trial, a dot was superimposed at a given location on the contour (Experiment 1) or within and around the shape (Experiment 2). The participant’s task was to place a dot at the corresponding location on the right side of the screen. By analyzing correspondence between responses and physical transformations, we tested for object constancy, causal history, and transformation of space. We find that shape representations are remarkably robust against rotation and scaling. Performance is modulated by the type and amount of transformation, as well as by contour saliency. We also find that the representation of space within and around a shape is transformed in line with the shape transformation, as if shape features establish an object-centered reference frame. These findings suggest robust mechanisms for the inference of shape, space and correspondence across transformations.

Egocentric representations of space co-exist with allocentric representations: Evidence from spatial neglect

The brain transforms sensory input to motor coordinates to accommodate for changes of posture and gaze direction. Neurophysiological and neuropsychological evidence supports the existence of multiple representations of space. A debated issue regards whether objects that we see are encoded in egocentric frames only or also maintain an object-centered frame of reference. Previous clinical studies were unable to discriminate between these models as the stimuli used to determine object-based (allocentric) biases are contaminated by body-centered (egocentric) effects. To address this, we used stimuli where allocentric side was elicited by gestalt configuration rather than egocentric location. We then displayed these stimuli at different egocentric positions allowing us to independently measure the effects of allocentric position, egocentric position as well as their interaction. In a group of stroke patients with neglect we demonstrate that allocentric biases are modulated as a function of egocentric position. These findings help adjudicate between the different models of space representation, demonstrating that specific allocentric deficits not only exist but also often co-exist with egocentric biases.

Object-centered orienting and IOR.

Three recent studies reported retinotopic (eye-centered) and object-centered attentional facilitation following exogenous cuing in dynamic displays. The present study replicates this finding and shows, under the very same experimental conditions, inhibition of return (IOR) in both retinotopic and object-centered reference frames. Unlike in previous findings, we show that when a single object is present in the display, IOR is bound to both retinotopic and object-centered locations, defined as a specific location within the boundaries of a single object.

The spatially asymmetric cost of memory load on visual perception: Transient stimulus-centered neglect.

Recent evidence suggests that visual working memory (VWM) load reduces performance accuracy on a concurrent visual recognition task, particularly for objects presented in the left hemifield. It has also been shown that high VWM load causes suppression of activity in the right temporoparietal junction (TPJ). Given the resemblance of VWM load effects to symptoms of unilateral neglect (i.e., impaired perception on the left side and lesion to the right TPJ), we investigated whether VWM load effects are restricted to the left side of space or extend to object-centered reference frames. In other words, akin to object-centered neglect, can high VWM load cause a perceptual cost in attending to the left side of the stimulus? We addressed this question using an object recognition task (Experiment 1) and a visual search task (Experiment 2) showing that this transient left-neglect can indeed be modulated by an object-centered frame of reference. These findings suggest that load-induced impairments of visual attention are spatially asymmetric and can emerge within multiple spatial reference frames. Therefore, the attentional consequences of high VWM load on conscious perception may serve as a useful model of unilateral perceptual neglect.

Object-centered reference frames in depth as revealed by induced motion

An object-centric reference frame is a spatial representation in which objects or their parts are coded relative to others. The existence of object-centric representations is supported by the phenomenon of induced motion, in which the motion of an inducer frame in a particular direction induces motion in the opposite direction in a target dot. We report on an experiment made with an induced motion display where a degree of slant is imparted to the inducer frame using either perspective or binocular disparity depth cues. Critically, the inducer frame oscillates perpendicularly to the line of sight, rather than moving in depth. Participants matched the perceived induced motion of the target dot in depth using a 3D rotatable rod. Although the frame did not move in depth, we found that subjects perceived the dot as moving in depth, either along the slanted frame or against it, when depth was given by perspective and disparity, respectively. The presence of induced motion is thus not only due to the competition among populations of planar motion filters, but rather incorporates 3D scene constraints. We also discuss this finding in the context of the uncertainty related to various depth cues, and to the locality of representation of reference frames.

Functional and structural architecture of the human dorsal frontoparietal attention network

The dorsal frontoparietal attention network has been subdivided into at least eight areas in humans. However, the circuitry linking these areas and the functions of different circuit paths remain unclear. Using a combination of neuroimaging techniques to map spatial representations in frontoparietal areas, their functional interactions, and structural connections, we demonstrate different pathways across human dorsal frontoparietal cortex for the control of spatial attention. Our results are consistent with these pathways computing object-centered and/or viewer-centered representations of attentional priorities depending on task requirements. Our findings provide an organizing principle for the frontoparietal attention network, where distinct pathways between frontal and parietal regions contribute to multiple spatial representations, enabling flexible selection of behaviorally relevant information.

Exogenous object-centered attention

The present paper shows that the exogenous spatial cueing effect moves along with a rotating object. We exogenously cued one side of a horizontal bar with an abrupt onset.After cueing, this bar rotated to a vertical position. We found an object-centered cueing effect. In a second experiment, we cued one arm of a rotating cross and showed that retinotopic(eye-centered) and object-centered cueing effects are equally strong. Our results indicate that retinotopic and object centered reference frames are simultaneously present and accessible. Consistent with neurophysiology, we argue that there are two dissociable attentional systems: one for visual object processing and one for spatial processing [corrected].

What is the hierarchical representation of tasks involving objects with complex internal dynamics?

Event Abstract Back to Event What is the hierarchical representation of tasks involving objects with complex internal dynamics? Anastasia Sylaidi1* and Aldo A. Faisal1, 2 1 Imperial College London, Dep. of Bioengineering, United Kingdom 2 Imperial College London, Dep. of Computing, United Kingdom Motor circuits, limb kinematics and many real-world tasks are organised hierarchically [1-2]. This prompts the question how the brain represents hierarchical task dependencies and how these are mapped onto the nervous system and control of movement. It was previously suggested that the CNS represents object manipulation tasks with regard to an intrinsic frame of reference centered on the body’s actuators and sensors and/or an extrinsic frame of reference related to task context, environmental settings or properties of point-like objects [3-5]. Ultimately, these two reference frames have to be linked to support the completion of high-level tasks [1], such as pouring wine into a glass. Here, we examine how joint- and body-based reference frames are organised as parts of a hierarchical structure of task representation that underlies motor learning. Towards this end we focus on the manipulation of objects with naturalistic internal dynamic. We test 3 possible hierarchical schemes of motor learning in object manipulation tasks: (a) In the first one task dynamics are principally learned and represented in intrinsic joint-based reference frames, on which the extrinsic reference frame of the object depends. This predicts, that humans generalise learned motor tasks over all joint space, but with regard to only one object orientation. (b) Conversely, in the second scheme, task dynamics are principally learned in an object-centered reference frame. This predicts generalisation across object orientations, but not across joint configurations. (c) In the third scheme both reference frames are learned independently. In order to test which of the three candidate mechanisms underlies motor control we conducted a behavioural study. Human subjects were asked to perform a rotational task within a given accuracy inside a 3D virtual reality setup, using a bottle of complex or static internal dynamics. In 2 different experiments subjects learned a single training task and were subsequently instructed to complete multiple testing tasks, in which object or joint positioning varied (experiment 1 and 2 respectively). Their performance was estimated in terms of pivot point displacement and used to examine how learning is transferred from training to testing conditions. Our results revealed a significant increase of pivot point displacement from training to testing phases in both experiments and for both object types. (Wilcoxon test, p<0.0125). This increase demonstrates a poor generalization capability of learned task dynamics to novel task contexts. This observation provides supporting evidence that task representations are independently learned for both the body-centered and object-centered coordinate frames and ad-hoc combined during motor actions. Our results lead to further investigations of the frames’ respective timescales, their potentially weighted contribution to motor learning, as well as the dependence of this weight on the nature of object dynamics.

Nonretinotopic Exogenous Attention

Attention is crucial for visual perception because it allows the visual system to effectively use its limited resources by selecting behaviorally and cognitively relevant stimuli from the large amount of information impinging on the eyes. Reflexive, stimulus-driven attention is essential for successful interactions with the environment because it can, for example, speed up responses to life-threatening events. It is commonly believed that exogenous attention operates in the retinotopic coordinates of the early visual system. Here, using a novel experimental paradigm [1], we show that a nonretinotopic cue improves both accuracy and reaction times in a visual search task. Furthermore, the influence of the cue is limited both in space and time, a characteristic typical of exogenous cueing. These and other recent findings show that many more aspects of vision are processed nonretinotopically than previously thought.

Using MVPA to dissociate the role of object-centered and eye-centered reference frames in attention

Using MVPA to dissociate the role of object-centered and eye-centered reference frames in attention

A neural model for the visual tuning properties of action-selective neurons

AbstractSUMMARY: The recognition of actions of conspecifics is crucial for survival and social interaction. Most current models on the recognition of transitive (goal-directed) actions rely on the hypothesized role of internal motor simulations for action recognition. However, these models do not specify how visual information can be processed by cortical mechanisms in order to be compared with such motor representations. This raises the question how such visual processing might be accomplished, and in how far motor processing is critical in order to account for the visual properties of action-selective neurons.We present a neural model for the visual processing of transient actions that is consistent with physiological data and that accomplishes recognition of grasping actions from real video stimuli. Shape recognition is accomplished by a view-dependent hierarchical neural architecture that retains some coarse position information on the highest level that can be exploited by subsequent stages. Additionally, simple recurrent neural circuits integrate effector information over time and realize selectivity for temporal sequences. A novel mechanism combines information about the shape and position of object and effector in an object-centered frame of reference. Action-selective model neurons defined in such a relative reference frame are tuned to learned associations between object and effector shapes, as well as their relative position and motion.We demonstrate that this model reproduces a variety of electrophysiological findings on the visual properties of action-selective neurons in the superior temporal sulcus, and of mirror neurons in area F5. Specifically, the model accounts for the fact that a majority of mirror neurons in area F5 show view dependence. The model predicts a number of electrophysiological results, which partially could be confirmed in recent experiments.We conclude that the tuning of action-selective neurons given visual stimuli can be accounted for by well-established, predominantly visual neural processes rather than internal motor simulations. METHODS: The shape recognition relies on a hierarchy of feature detectors of increasing complexity and invariance [1]. The mid-level features are learned from sequences of gray-level images depicting segmented views of hand and object shapes. The highest hierarchy level consists of detector populations for complete shapes with a coarse spatial resolution of approximately 3.7°. Additionally, effector shapes are integrated over time by asymmetric lateral connections between shape detectors using a neural field approach [2]. These model neurons thus encode actions such as hand opening or closing for particular grip types.We exploit gain field mechanism in order to implement the central coordinate transformation of the shape representations to an object-centered reference frame [3]. Typical effector-object-interactions correspond to activity regions in such a relative reference frame and are learned from training examples. Similarly, simple motion-energy detectors are applied in the object-centered reference frame and encode relative motion. The properties of transitive action neurons are modeled as a multiplicative combination of relative shape and motion detectors. RESULTS: The model performance was tested on a set of 160 unsegmented sequences of hand grasping or placing actions performed on objects of different sizes, using different grip types and views. Hand actions and objects could be reliably recognized despite their mutual occlusions. Detectors on the highest level showed correct action tuning in more than 95% of the examples and generalized to untrained views.Furthermore, the model replicates a number of electrophysiological as well as imaging experiments on action-selective neurons, such as their particular selectivity for transitive actions compared to mimicked actions, the invariance to stimulus position, and their view-dependence. In particular, using the same stimulus set the model nicely fits neural data from a recent electrophysiological experiment that confirmed sequence selectivity in mirror neurons in area F5, as was predicted before by the model.

From Motion to Object: How Visual Cortex Does Motion Vector Decomposition to Create Object-Centered Reference Frames

From Motion to Object: How Visual Cortex Does Motion Vector Decomposition to Create Object-Centered Reference Frames

Mirror-image confusions: Implications for representation and processing of object orientation

Perceiving the orientation of objects is important for interacting with the world, yet little is known about the mental representation or processing of object orientation information. The tendency of humans and other species to confuse mirror images provides a potential clue. However, the appropriate characterization of this phenomenon is not entirely clear, in part because the stimuli used in most previous studies were not adequate for distinguishing various forms of mirror-image and non-mirror-image error. In the present study we explore the nature of mirror-image confusion and what the phenomenon can reveal about object-orientation representations. We report several experiments in which participants reported the orientations of pictures. In all of the experiments mirror-reflection errors were more frequent than other orientation errors. However, whereas mirror-image confusion has previously been described as a tendency to confuse stimuli that are related by reflection across an extrinsic (usually vertical) axis, the vast majority of mirror-image errors in our experiments were reflections across an object axis. This finding calls into question several hypotheses proposed to explain mirror-image confusion. We describe a coordinate-system orientation representation (COR) hypothesis that can account for our results ( McCloskey, Valtonen, & Sherman, 2006). COR assumes that orientation representations map an object-centered reference frame onto a reference frame extrinsic to the object, with this mapping specified by several parameters. According to COR, mirror-image confusions and other orientation errors arise from failures in representing or processing specific parameters. Considered in light of COR, our results suggest that orientation representations are compositional, and that object-centered reference frames play a central role in orientation representation.

The dynamic routing model of visuospatial attention

Event Abstract Back to Event The dynamic routing model of visuospatial attention Bruce Bobier1*, Terry Stewart1 and Chris Eliasmith1 1 University of Waterloo, Canada The dynamic control of information routing in the brain has been most extensively studied in the context of visual attention, although the underlying mechanisms employed by the involved neural populations remain unclear. Several models have suggested that selective routing of attended information may be performed by modulating the gain of stimulus representations or by modifying synaptic connection weights. A problem with many such models is that they do not address how these processes are performed at the cellular level, or do so in a biologically implausible manner. Here we present the Dynamic Routing Model (DRM), which frames the problem of visuospatial attention as the dynamic routing information through a hierarchy of topographically organized cortical regions to an object-centered reference frame. In the DRM, the inferior and lateral pulvinar are hypothesized to encode the retinotopic location at which attention should be engaged, and project this signal to cortical control columns in each visual area. Each control column serves to guide information routing for a small group of adjacent visual columns. At each layer, the pulvinar signal is transformed by the cortical control columns to encode the location from which information should be represented. The dendrites of a neuron in a given column encode a vector containing the control signal and its inputs, and the synaptic weights of the dendrites collectively serve to approximate a function that modulates the gain of each input depending on its distance from the location specified by the cortical control signal. We begin by considering the attentional routing performed in a five layer hierarchy, where each layer is reciprocally connected with pulvinar. For each visual column, we can determine the interactions between the control and visual inputs that are required to optimally route information from the focus of attention to an object-centered reference frame at the top layer. After defining this interaction, we next investigate whether this function can be represented within the dendrites. The routing mechanism is the same for all nodes in the hierarchy, and by using the Neural Engineering Framework to model a subset of this large-scale network, we can use this high level mathematical description to analytically derive the optimal connection weights to perform the routing function. Simulation results show that in a model composed of a single cortical control population and nine visual columns, each containing 200 LIF neurons that project to a single output population, the neurons are able to accurately route visual information. We then show that the model accounts for numerous findings from neurophysiological and psychophysical studies, including attentional effects occurring earlier and more strongly in higher cortical areas, dynamic receptive field shifts, center-surround suppression, as well as impairments observed in pulvinar lesion patients. The DRM also generates several predictions concerning the character of the suppressive annulus surrounding the focus of attention, the role of pulvinar in engaging attention, and the computations performed by cortical neurons under attention. Conference: Computational and Systems Neuroscience 2010, Salt Lake City, UT, United States, 25 Feb - 2 Mar, 2010. Presentation Type: Poster Presentation Topic: Poster session III Citation: Bobier B, Stewart T and Eliasmith C (2010). The dynamic routing model of visuospatial attention. Front. Neurosci. Conference Abstract: Computational and Systems Neuroscience 2010. doi: 10.3389/conf.fnins.2010.03.00121 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 Mar 2010; Published Online: 01 Mar 2010. * Correspondence: Bruce Bobier, University of Waterloo, Waterloo, Canada, bbobier@engmail.uwaterloo.ca Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Bruce Bobier Terry Stewart Chris Eliasmith Google Bruce Bobier Terry Stewart Chris Eliasmith Google Scholar Bruce Bobier Terry Stewart Chris Eliasmith PubMed Bruce Bobier Terry Stewart Chris Eliasmith Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Aligning body and world: Stable reference frames improve young children’s search for hidden objects

This study investigated how young children’s increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2- and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children who were given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels and significantly better than children who were given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning—aligning egocentric and object-centered reference frames—play a role in the ramp task during this transitional phase in development.

Parietal cortex, navigation, and the construction of arbitrary reference frames for spatial information

The registration of spatial information by neurons of the parietal cortex takes on many forms. In most experiments, spatially modulated parietal activity patterns are found to take as their frame of reference some part of the body such as the retina. However, recent findings obtained in single neuron recordings from both rat and monkey parietal cortex suggest that the frame of reference utilized by parietal cortex may also be abstract or arbitrary in nature. Evidence in rats comes from work indicating that parietal activity in freely behaving rodents is organized according to the space defined by routes taken through an environment. In monkeys, evidence for an object-centered frame of reference has recently been presented. The present work reviews single neuron recording experiments in parietal cortex of freely behaving rats and considers the potential contribution of parietal cortex in solving navigational tasks. It is proposed that parietal cortex, in interaction with the hippocampus, plays a critical role in the selection of the most appropriate route between two points and, in addition, produces a route-based positional signal capable of guiding sensorimotor transitions.