Perception Of Object Motion Research Articles

Non-visual self-motion information influences the perception of object motion while walking

Non-visual self-motion information influences the perception of object motion while walking

Two Modes of Motion Perception: A Double-dissociation of the effects of contrast and field of view on perception of object-motion and self-motion

Two Modes of Motion Perception: A Double-dissociation of the effects of contrast and field of view on perception of object-motion and self-motion

Visual and non-visual contributions to the perception of object motion during self-motion

Many locomotor tasks involve interactions with moving objects. When observer (i.e., self-)motion is accompanied by object motion, the optic flow field includes a component due to self-motion and a component due to object motion. For moving observers to perceive the movement of other objects relative to the stationary environment, the visual system could recover the object-motion component – that is, it could factor out the influence of self-motion. In principle, this could be achieved using visual self-motion information, non-visual self-motion information, or a combination of both. In this study, we report evidence that visual information about the speed (Experiment 1) and direction (Experiment 2) of self-motion plays a role in recovering the object-motion component even when non-visual self-motion information is also available. However, the magnitude of the effect was less than one would expect if subjects relied entirely on visual self-motion information. Taken together with previous studies, we conclude that when self-motion is real and actively generated, both visual and non-visual self-motion information contribute to the perception of object motion. We also consider the possible role of this process in visually guided interception and avoidance of moving objects.

Acoustic facilitation of object movement detection during self-motion

In humans, as well as most animal species, perception of object motion is critical to successful interaction with the surrounding environment. Yet, as the observer also moves, the retinal projections of the various motion components add to each other and extracting accurate object motion becomes computationally challenging. Recent psychophysical studies have demonstrated that observers use a flow-parsing mechanism to estimate and subtract self-motion from the optic flow field. We investigated whether concurrent acoustic cues for motion can facilitate visual flow parsing, thereby enhancing the detection of moving objects during simulated self-motion. Participants identified an object (the target) that moved either forward or backward within a visual scene containing nine identical textured objects simulating forward observer translation. We found that spatially co-localized, directionally congruent, moving auditory stimuli enhanced object motion detection. Interestingly, subjects who performed poorly on the visual-only task benefited more from the addition of moving auditory stimuli. When auditory stimuli were not co-localized to the visual target, improvements in detection rates were weak. Taken together, these results suggest that parsing object motion from self-motion-induced optic flow can operate on multisensory object representations.

Differential effects of contrast and field size on the perception of object-motion and self-motion: new evidence for ambient and focal modes of vision

Differential effects of contrast and field size on the perception of object-motion and self-motion: new evidence for ambient and focal modes of vision

Unaffected perceptual thresholds for biological and non-biological form-from-motion perception in autism spectrum conditions.

BackgroundPerception of biological motion is linked to the action perception system in the human brain, abnormalities within which have been suggested to underlie impairments in social domains observed in autism spectrum conditions (ASC). However, the literature on biological motion perception in ASC is heterogeneous and it is unclear whether deficits are specific to biological motion, or might generalize to form-from-motion perception.Methodology and Principal FindingsWe compared psychophysical thresholds for both biological and non-biological form-from-motion perception in adults with ASC and controls. Participants viewed point-light displays depicting a walking person (Biological Motion), a translating rectangle (Structured Object) or a translating unfamiliar shape (Unstructured Object). The figures were embedded in noise dots that moved similarly and the task was to determine direction of movement. The number of noise dots varied on each trial and perceptual thresholds were estimated adaptively. We found no evidence for an impairment in biological or non-biological object motion perception in individuals with ASC. Perceptual thresholds in the three conditions were almost identical between the ASC and control groups.Discussion and ConclusionsImpairments in biological motion and non-biological form-from-motion perception are not across the board in ASC, and are only found for some stimuli and tasks. We discuss our results in relation to other findings in the literature, the heterogeneity of which likely relates to the different tasks performed. It appears that individuals with ASC are unaffected in perceptual processing of form-from-motion, but may exhibit impairments in higher order judgments such as emotion processing. It is important to identify more specifically which processes of motion perception are impacted in ASC before a link can be made between perceptual deficits and the higher-level features of the disorder.

Perception of object motion in three-dimensional space induced by cast shadows

Cast shadows can be salient depth cues in three-dimensional (3D) vision. Using a motion illusion in which a ball is perceived to roll in depth on the bottom or to flow in the front plane depending on the slope of the trajectory of its cast shadow, we investigated cortical mechanisms underlying 3D vision based on cast shadows using fMRI techniques. When modified versions of the original illusion, in which the slope of the shadow trajectory (shadow slope) was changed in 5 steps from the same one as the ball trajectory to the horizontal, were presented to participants, their perceived ball trajectory shifted gradually from rolling on the bottom to floating in the front plane as the change of the shadow slope. This observation suggests that the perception of the ball trajectory in this illusion is strongly affected by the motion of the cast shadow. In the fMRI study, cortical activity during observation of the movies of the illusion was investigated. We found that the bilateral posterior-occipital sulcus (POS) and right ventral precuneus showed activation related to the perception of the ball trajectory induced by the cast shadows in the illusion. Of these areas, it was suggested that the right POS may be involved in the inferring of the ball trajectory by the given spatial relation between the ball and the shadow. Our present results suggest that the posterior portion of the medial parietal cortex may be involved in 3D vision by cast shadows.

The role of hMST in the perception of object movement during self-movement

The role of hMST in the perception of object movement during self-movement

The role of multi-area interactions for the computation of apparent motion

Apparent motion (AM) is a robust visual illusion, in which fast displays of static objects in successively different positions elicit the perception of object motion. Neurons in higher order areas 21 and 19 compute object motion under such conditions and send feedback to early visual areas 18 and 17, which is instrumental in eliciting computation of motion in those very areas. To explore the computational dynamics of AM, we made a neural field model consisting of two one-dimensional rings of simple neurons expressing firing rates, one for areas 17/18 and one for areas 19/21. The model neurons, without any orientation or direction selectivity, computed apparent motion for the range of space-timings of stimuli associated with short- and long-range AM in humans. The computation of long-range AM in 17/18 required two model areas and the presence of feedback and conduction/computation delays between those areas. As in the in vivo experiments of long-range AM, the stationary stimuli were initially mapped as stationary in model area 17/18, but after the feedback also these lower areas computed AM. The dynamics of the two-area network produces short-range and long-range apparent motion for a large range of feedback strengths and a small range of lateral excitation near the bifurcation to an amplitude instability. The computation of AM in higher order areas was due to the neurons in these areas having large receptive fields as a consequence of divergent feed-forward connectivity. This implies that these areas compute long-range AM when early areas 17 and 18 do not, and therefore higher order areas must enslave lower order areas to compute the same, if the whole network is to arrive at a coherent perceptual solution.

The contributions of edges and surfaces to the perception of object motion

The contributions of edges and surfaces to the perception of object motion

Motion perception during smooth pursuit eye movements: object and background motion perception depend on different non-retinal signals on eye velocity

Motion perception during smooth pursuit eye movements: object and background motion perception depend on different non-retinal signals on eye velocity

Long-range coupling of prefrontal cortex and visual (MT) or polysensory (STP) cortical areas in motion perception

Event Abstract Back to Event Long-range coupling of prefrontal cortex and visual (MT) or polysensory (STP) cortical areas in motion perception Lucia M. Vaina1, 2*, Finnegan Calabro1, Fa-Hsuan Lin2 and Matti Hamalainen3 1 Boston University, United States 2 Harvard University, United States 3 Massachusetts General Hospital, United States To investigate how, where and when moving auditory cues interact with the perception of object-motion during self-motion, we conducted psychophysical, and MEG experiments in which the subjects viewed nine textured objects during simulated forward self-motion. On each trial, one object was randomly assigned its own looming motion within the scene. Subjects reported which of four labeled objects had independent motion within the scene in two conditions: (1) visual information only and (2) with additional auditory cue. In psychophysics, observers performed slightly better in the presence of an auditory cue moving in the same direction with the object target (p=0.003, t=4.18, df=8, min 1.2%, and max 8.1). When the auditory cue was static, uninformative, it had not impact on performance. In cortically-constrained MEG source estimates, comparison of the two conditions showed: (i) MT (middle temporal area) activity similar across conditions; (ii) additional activity in the auditory cue condition ventral to MT late after the stimulus presentation; (iii) with the auditory cue, early activity at the right auditory cortex (AC) together with STP (superior temporal polysensory area), (iv) different time courses of these two activities with STP signals later in the epoch together with frontal activity in the right hemisphere, (v) stronger activity in PPC (posterior parietal cortex) in the visual-only condition than in the auditory-cue condition. In addition, Dynamic Granger Causality analysis among cortical regions showed for the auditory cues condition a strong connection of the AC with STP but not with MT suggesting binding of visual and auditory information at STP. Also, while in the visual-only condition PFC is connected with MT, in the auditory-cue condition PFC (prefrontal cortex) is connected to STP. These results indicate that PFC allocates attention to the “object” as a whole, in STP to a moving visual-auditory object, and in MT to a moving visual object. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: Sensory Processing and Functional Connectivity Citation: Vaina LM, Calabro F, Lin F and Hamalainen M (2010). Long-range coupling of prefrontal cortex and visual (MT) or polysensory (STP) cortical areas in motion perception. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00212 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: 30 Mar 2010; Published Online: 30 Mar 2010. * Correspondence: Lucia M Vaina, Boston University, Boston, United States, vaina@bu.edu 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 Lucia M Vaina Finnegan Calabro Fa-Hsuan Lin Matti Hamalainen Google Lucia M Vaina Finnegan Calabro Fa-Hsuan Lin Matti Hamalainen Google Scholar Lucia M Vaina Finnegan Calabro Fa-Hsuan Lin Matti Hamalainen PubMed Lucia M Vaina Finnegan Calabro Fa-Hsuan Lin Matti Hamalainen 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.

Spatiotemporal aspects of pulsed electrical stimuli on the responses of rabbit retinal ganglion cells

Implanted intraocular microelectrode arrays are being used to provide sight to individuals who are blind due to photoreceptor degeneration. It is envisioned that this retinal prosthesis will create the illusion of motion by stimulating focal areas of the retina in a sequential fashion through neighboring electrodes, much like the rapid succession of still images in movies and computer animation gives rise to apparent motion. Using a high-density microelectrode array, we examined the extracellularly recorded responses of rabbit retinal ganglion cells to a bar-shaped electrode array that was stepped at 50 μm increments at different rates across the retina and compared these respons2es to the responses generated to a similarly shaped light stimulus that was stepped across the retina. When the retina was stimulated at 1 step/s, retinal ganglion cells gave robust bursts of action potentials to both the electrode array and the light stimulus. The responses to the ‘moving’ electrode array decreased progressively with increasing stepping frequency. At 16 steps/s (highest frequency tested), the number of spikes per sweep and the number of bursts per sweep were reduced 75% and 67% respectively. In contrast, when the retina was stimulated at 16 steps/s with the ‘moving’ light stimulus, the number of spikes per sweep and the number of bursts per sweep were reduced only 43% and 25% respectively. These findings suggest that simple translation of object motion to sequential stimulation through neighboring electrodes may not be the best way to convey the perception of object motion in a patient with a retinal prosthesis.

Object manipulation and motion perception: Evidence of an influence of action planning on visual processing.

In 3 experiments, the authors investigated the bidirectional coupling of perception and action in the context of object manipulations and motion perception. Participants prepared to grasp an X-shaped object along one of its 2 diagonals and to rotate it in a clockwise- or a counterclockwise direction. Action execution had to be delayed until the appearance of a visual go signal, which induced an apparent rotational motion in either a clockwise- or a counterclockwise direction. Stimulus detection was faster when the direction of the induced apparent motion was consistent with the direction of the concurrently intended manual object rotation. Responses to action-consistent motions were also faster when the participants prepared the manipulation actions but signaled their stimulus detections with another motor effector (i.e., with a foot response). Taken together, the present study demonstrates a motor-visual priming effect of prepared object manipulations on visual motion perception, indicating a bidirectional functional link between action and perception beyond object-related visuomotor associations.

World-centered perception of 3D object motion during visually guided self-motion

We investigated how human observers estimate an object's three-dimensional (3D) motion trajectory during visually guided self-motion. Observers performed a task in an immersive virtual reality system consisting of front, left, right, and floor screens of a room-sized cube. In one experiment, we found that the presence of an optic flow simulating forward self-motion in the background induces a world-centered frame of reference, instead of an observer-centered frame of reference, for the perceived rotation of a 3D surface from motion. In another experiment, we found that the perceived direction of 3D object motion is biased toward a world-centered frame of reference when an optic flow pattern is presented in the background. In a third experiment, we confirmed that the effect of the optic flow pattern on the perceived direction of 3D object motion was not caused only by local motion detectors responsible for the change of the retinal size of the target. These results suggest that visually guided self-motion from optic flow induces world-centered criteria for estimates of 3D object motion.

From monkey calls to human words? An evolutionary perspective on the neural basis of the conceptual representation and vocal communication systems

Event Abstract Back to Event From monkey calls to human words? An evolutionary perspective on the neural basis of the conceptual representation and vocal communication systems Ricardo Gil-da-Costa1* 1 The Salk Institute for Biological Studies, Vision Center Laboratory, United States Mental representation of objects and events is a fundamental component of our cognitive processes. The very act of thinking needs implicit content that can be acquired both by ontogeny, and by phylogeny through species evolution. Non-human primates produce a diverse repertoire of species-specific calls and have rich conceptual systems. These calls are designed to convey information about concepts such as predators, food, and social relationships, as well as the affective state of the caller, making vocal communication a powerful ‘tool’ to probe their conceptual representation system. We reported neurophysiological evidence for the evolution of the conceptual representation system. Our results indicate differential activation by categorical association with recall-related activity in higher-order visual areas by auditory meaningful stimuli. These areas included regions in the inferior temporal lobe associated with the visual perception of object form (TE/TEO) and motion (STS, MT) and in storing visual object information into long-term memory (TE). Brain patterns of selective activity were also found in limbic (the amygdala and hippocampus), and paralimbic regions (ventromedial prefrontal cortex) associated with the interpretation and memory encoding of highly salient and affective material and knowledge of conspecifics. This neural circuitry strongly corresponds to the network shown in humans. These findings advance our understanding on the evolution of conceptual representation and long-term memory systems, suggesting that monkeys and humans have a common neural substrate for representing object concepts. Moreover, we have found that such vocalizations, but not control stimuli, evoke distinct patterns of brain activity in ventrolateral frontal cortex (PmV) and Tpt, areas previously reported as the structural homologues of Broca’s and Wernicke’s, the human perisylvian language areas. The activation of these homologue areas may represent a way of coupling meaning encoded in sound to the more general conceptual system. These findings support the hypothesis that the common ancestor of macaques and humans, 25-30 million years ago already possessed the key neural mechanisms later exapted for the evolution of language. Lastly, the knowledge gained by the integration of findings in the macaque with correlated findings in humans should help us move towards the use of these primates as an animal model for human disorders in which the semantic system is affected. Conference: 11th Meeting of the Portuguese Society for Neuroscience, Braga, Portugal, 4 Jun - 6 Jun, 2009. Presentation Type: Oral Presentation Topic: Symposium 2 – Brain Networks Citation: Gil-da-Costa R (2009). From monkey calls to human words? An evolutionary perspective on the neural basis of the conceptual representation and vocal communication systems. Front. Neurosci. Conference Abstract: 11th Meeting of the Portuguese Society for Neuroscience. doi: 10.3389/conf.neuro.01.2009.11.016 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: 05 Aug 2009; Published Online: 05 Aug 2009. * Correspondence: Ricardo Gil-da-Costa, The Salk Institute for Biological Studies, Vision Center Laboratory, La Jolla, United States, ricardo@salk.edu 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 Ricardo Gil-da-Costa Google Ricardo Gil-da-Costa Google Scholar Ricardo Gil-da-Costa PubMed Ricardo Gil-da-Costa 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.

Filling-in visual motion with sounds

Information about the motion of objects can be extracted by multiple sensory modalities, and, as a consequence, object motion perception typically involves the integration of multi-sensory information. Often, in naturalistic settings, the flow of such information can be rather discontinuous (e.g. a cat racing through the furniture in a cluttered room is partly seen and partly heard). This study addressed audio-visual interactions in the perception of time-sampled object motion by measuring adaptation after-effects. We found significant auditory after-effects following adaptation to unisensory auditory and visual motion in depth, sampled at 12.5Hz. The visually induced (cross-modal) auditory motion after-effect was eliminated if visual adaptors flashed at half of the rate (6.25Hz). Remarkably, the addition of the high-rate acoustic flutter (12.5Hz) to this ineffective, sparsely time-sampled, visual adaptor restored the auditory after-effect to a level comparable to what was seen with high-rate bimodal adaptors (flashes and beeps). Our results suggest that this auditory-induced reinstatement of the motion after-effect from the poor visual signals resulted from the occurrence of sound-induced illusory flashes. This effect was found to be dependent both on the directional congruency between modalities and on the rate of auditory flutter. The auditory filling-in of time-sampled visual motion supports the feasibility of using reduced frame rate visual content in multisensory broadcasting and virtual reality applications.

Perception of object trajectory: Parsing retinal motion into self and object movement components

A moving observer needs to be able to estimate the trajectory of other objects moving in the scene. Without the ability to do so, it would be difficult to avoid obstacles or catch a ball. We hypothesized that neural mechanisms sensitive to the patterns of motion generated on the retina during self-movement (optic flow) play a key role in this process, "parsing" motion due to self-movement from that due to object movement. We investigated this "flow parsing" hypothesis by measuring the perceived trajectory of a moving probe placed within a flow field that was consistent with movement of the observer. In the first experiment, the flow field was consistent with an eye rotation; in the second experiment, it was consistent with a lateral translation of the eyes. We manipulated the distance of the probe in both experiments and assessed the consequences. As predicted by the flow parsing hypothesis, manipulating the distance of the probe had differing effects on the perceived trajectory of the probe in the two experiments. The results were consistent with the scene geometry and the type of simulated self-movement. In a third experiment, we explored the contribution of local and global motion processing to the results of the first two experiments. The data suggest that the parsing process involves global motion processing, not just local motion contrast. The findings of this study support a role for optic flow processing in the perception of object movement during self-movement.

Contrast and Assimilation in Motion Perception and Smooth Pursuit Eye Movements

The analysis of visual motion serves many different functions ranging from object motion perception to the control of self-motion. The perception of visual motion and the oculomotor tracking of a moving object are known to be closely related and are assumed to be controlled by shared brain areas. We compared perceived velocity and the velocity of smooth pursuit eye movements in human observers in a paradigm that required the segmentation of target object motion from context motion. In each trial, a pursuit target and a visual context were independently perturbed simultaneously to briefly increase or decrease in speed. Observers had to accurately track the target and estimate target speed during the perturbation interval. Here we show that the same motion signals are processed in fundamentally different ways for perception and steady-state smooth pursuit eye movements. For the computation of perceived velocity, motion of the context was subtracted from target motion (motion contrast), whereas pursuit velocity was determined by the motion average (motion assimilation). We conclude that the human motion system uses these computations to optimally accomplish different functions: image segmentation for object motion perception and velocity estimation for the control of smooth pursuit eye movements.

Neural activity involved in the perception of human and meaningful object motion

We characterized magnetoencephalographic responses during observation of point-light displays of human and object motion. Time courses of grand-mean source estimates were computed and time frequency maps were calculated. For both conditions, activity began in the posterior occipital and mid-parietal areas. Further, late peaks were observed in the parietal, sensory-motor and left temporal regions. Only observation of human motion resulted in activation of the right temporal area. Both viewing conditions resulted in alpha and beta event-related desynchronization over the parietal, sensory-motor and temporal areas. A significant increase in beta activity was seen in the posterior temporal region in the human motion condition. The visual analyses of human and object motion appear to involve both overlapping and divergent patterns of neural activity.