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He D, Öğmen H. A neural model for vector decomposition and relative-motion perception. Vision Res 2023; 202:108142. [PMID: 36423519 DOI: 10.1016/j.visres.2022.108142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 09/22/2022] [Accepted: 10/27/2022] [Indexed: 11/22/2022]
Abstract
The perception of motion not only depends on the detection of motion signals but also on choosing and applying reference-frames according to which motion is interpreted. Here we propose a neural model that implements the common-fate principle for reference-frame selection. The model starts with a retinotopic layer of directionally-tuned motion detectors. The Gestalt common-fate principle is applied to the activities of these detectors to implement in two neural populations the direction and the magnitude (speed) of the reference-frame. The output activities of retinotopic motion-detectors are decomposed using the direction of the reference-frame. The direction and magnitude of the reference-frame are then applied to these decomposed motion-vectors to generate activities that reflect relative-motion perception, i.e., the perception of motion with respect to the prevailing reference-frame. We simulated this model for classical relative motion stimuli, viz., the three-dot, rotating-wheel, and point-walker (biological motion) paradigms and found the model performance to be close to theoretical vector decomposition values. In the three-dot paradigm, the model made the prediction of perceived curved-trajectories for the target dot when its horizontal velocity was slower or faster than the flanking dots. We tested this prediction in two psychophysical experiments and found a good qualitative and quantitative agreement between the model and the data. Our results show that a simple neural network using solely motion information can account for the perception of group and relative motion.
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Affiliation(s)
- Dongcheng He
- Laboratory of Perceptual and Cognitive Dynamics, University of Denver, Denver, CO, USA; Department of Electrical & Computer Engineering, University of Denver, Denver, CO, USA; Ritchie School of Engineering & Computer Science, University of Denver, Denver, CO, USA
| | - Haluk Öğmen
- Laboratory of Perceptual and Cognitive Dynamics, University of Denver, Denver, CO, USA; Department of Electrical & Computer Engineering, University of Denver, Denver, CO, USA; Ritchie School of Engineering & Computer Science, University of Denver, Denver, CO, USA.
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2
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Tripathy SP, Öǧmen H. Sensory Memory Is Allocated Exclusively to the Current Event-Segment. Front Psychol 2018; 9:1435. [PMID: 30245646 PMCID: PMC6137426 DOI: 10.3389/fpsyg.2018.01435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 07/23/2018] [Indexed: 11/18/2022] Open
Abstract
The Atkinson-Shiffrin modal model forms the foundation of our understanding of human memory. It consists of three stores (Sensory Memory (SM), also called iconic memory, Short-Term Memory (STM), and Long-Term Memory (LTM)), each tuned to a different time-scale. Since its inception, the STM and LTM components of the modal model have undergone significant modifications, while SM has remained largely unchanged, representing a large capacity system funneling information into STM. In the laboratory, visual memory is usually tested by presenting a brief static stimulus and, after a delay, asking observers to report some aspect of the stimulus. However, under ecological viewing conditions, our visual system receives a continuous stream of inputs, which is segmented into distinct spatio-temporal segments, called events. Events are further segmented into event-segments. Here we show that SM is not an unspecific general funnel to STM but is allocated exclusively to the current event-segment. We used a Multiple-Object Tracking (MOT) paradigm in which observers were presented with disks moving in different directions, along bi-linear trajectories, i.e., linear trajectories, with a single deviation in direction at the mid-point of each trajectory. The synchronized deviation of all of the trajectories produced an event stimulus consisting of two event-segments. Observers reported the pre-deviation or the post-deviation directions of the trajectories. By analyzing observers' responses in partial- and full-report conditions, we investigated the involvement of SM for the two event-segments. The hallmarks of SM hold only for the current event segment. As the large capacity SM stores only items involved in the current event-segment, the need for event-tagging in SM is eliminated, speeding up processing in active vision. By characterizing how memory systems are interfaced with ecological events, this new model extends the Atkinson-Shiffrin model by specifying how events are stored in the first stage of multi-store memory systems.
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Affiliation(s)
- Srimant P Tripathy
- School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom
| | - Haluk Öǧmen
- Department of Electrical and Computer Engineering, University of Denver, Denver, CO, United States
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3
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The reference frame for encoding and retention of motion depends on stimulus set size. Atten Percept Psychophys 2017; 79:888-910. [PMID: 28092077 DOI: 10.3758/s13414-016-1258-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The goal of this study was to investigate the reference frames used in perceptual encoding and storage of visual motion information. In our experiments, observers viewed multiple moving objects and reported the direction of motion of a randomly selected item. Using a vector-decomposition technique, we computed performance during smooth pursuit with respect to a spatiotopic (nonretinotopic) and to a retinotopic component and compared them with performance during fixation, which served as the baseline. For the stimulus encoding stage, which precedes memory, we found that the reference frame depends on the stimulus set size. For a single moving target, the spatiotopic reference frame had the most significant contribution with some additional contribution from the retinotopic reference frame. When the number of items increased (Set Sizes 3 to 7), the spatiotopic reference frame was able to account for the performance. Finally, when the number of items became larger than 7, the distinction between reference frames vanished. We interpret this finding as a switch to a more abstract nonmetric encoding of motion direction. We found that the retinotopic reference frame was not used in memory. Taken together with other studies, our results suggest that, whereas a retinotopic reference frame may be employed for controlling eye movements, perception and memory use primarily nonretinotopic reference frames. Furthermore, the use of nonretinotopic reference frames appears to be capacity limited. In the case of complex stimuli, the visual system may use perceptual grouping in order to simplify the complexity of stimuli or resort to a nonmetric abstract coding of motion information.
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4
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Öğmen H, Herzog MH. A New Conceptualization of Human Visual Sensory-Memory. Front Psychol 2016; 7:830. [PMID: 27375519 PMCID: PMC4899472 DOI: 10.3389/fpsyg.2016.00830] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/18/2016] [Indexed: 11/16/2022] Open
Abstract
Memory is an essential component of cognition and disorders of memory have significant individual and societal costs. The Atkinson–Shiffrin “modal model” forms the foundation of our understanding of human memory. It consists of three stores: Sensory Memory (SM), whose visual component is called iconic memory, Short-Term Memory (STM; also called working memory, WM), and Long-Term Memory (LTM). Since its inception, shortcomings of all three components of the modal model have been identified. While the theories of STM and LTM underwent significant modifications to address these shortcomings, models of the iconic memory remained largely unchanged: A high capacity but rapidly decaying store whose contents are encoded in retinotopic coordinates, i.e., according to how the stimulus is projected on the retina. The fundamental shortcoming of iconic memory models is that, because contents are encoded in retinotopic coordinates, the iconic memory cannot hold any useful information under normal viewing conditions when objects or the subject are in motion. Hence, half-century after its formulation, it remains an unresolved problem whether and how the first stage of the modal model serves any useful function and how subsequent stages of the modal model receive inputs from the environment. Here, we propose a new conceptualization of human visual sensory memory by introducing an additional component whose reference-frame consists of motion-grouping based coordinates rather than retinotopic coordinates. We review data supporting this new model and discuss how it offers solutions to the paradoxes of the traditional model of sensory memory.
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Affiliation(s)
- Haluk Öğmen
- Department of Electrical and Computer Engineering, University of HoustonHouston, TX, USA; Center for Neuro-Engineering and Cognitive Science, University of HoustonHouston, TX, USA
| | - Michael H Herzog
- Laboratory of Psychophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
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5
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Abstract
A reference frame is required to specify how motion is perceived. For example, the motion of part of an object is usually perceived relative to the motion of the object itself. Johansson (Psychological Research, 38, 379-393, 1976) proposed that the perceptual system carries out a vector decomposition, which rewsults in common and relative motion percepts. Because vector decomposition is an ill-posed problem, several studies have introduced constraints by means of which the number of solutions can be substantially reduced. Here, we have adopted an alternative approach and studied how, rather than why, a subset of solutions is selected by the visual system. We propose that each retinotopic motion vector creates a reference-frame field in the retinotopic space, and that the fields created by different motion vectors interact in order to determine a motion vector that will serve as the reference frame at a given point and time in space. To test this theory, we performed a set of psychophysical experiments. The field-like influence of motion-based reference frames was manifested by increased nonspatiotopic percepts of the backward motion of a target square with decreasing distance from a drifting grating. We then sought to determine whether these field-like effects of motion-based reference frames can also be extended to stationary landmarks. The results suggest that reference-field interactions occur only between motion-generated fields. Finally, we investigated whether and how different reference fields interact with each other, and found that different reference-field interactions are nonlinear and depend on how the motion vectors are grouped. These findings are discussed from the perspective of the reference-frame metric field (RFMF) theory, according to which perceptual grouping operations play a central and essential role in determining the prevailing reference frames.
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6
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Retinotopy of visual masking and non-retinotopic perception during masking. Atten Percept Psychophys 2015; 77:1263-84. [DOI: 10.3758/s13414-015-0844-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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7
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Agaoglu MN, Herzog MH, Öğmen H. The effective reference frame in perceptual judgments of motion direction. Vision Res 2015; 107:101-12. [PMID: 25536467 DOI: 10.1016/j.visres.2014.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 11/26/2014] [Accepted: 12/02/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Mehmet N Agaoglu
- Department of Electrical and Computer Engineering, University of Houston, N308 Engineering Building 1, Houston, TX 77204-4005, USA; Center for Neuro-Engineering and Cognitive Science, University of Houston, Houston, TX 77204-4005, USA
| | - Michael H Herzog
- Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Haluk Öğmen
- Department of Electrical and Computer Engineering, University of Houston, N308 Engineering Building 1, Houston, TX 77204-4005, USA; Center for Neuro-Engineering and Cognitive Science, University of Houston, Houston, TX 77204-4005, USA
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8
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Palinopsia revamped: A systematic review of the literature. Surv Ophthalmol 2015; 60:1-35. [DOI: 10.1016/j.survophthal.2014.06.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/23/2014] [Accepted: 06/24/2014] [Indexed: 02/07/2023]
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Herzog MH, Hermens F, Oğmen H. Invisibility and interpretation. Front Psychol 2014; 5:975. [PMID: 25278910 PMCID: PMC4166109 DOI: 10.3389/fpsyg.2014.00975] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 08/18/2014] [Indexed: 11/29/2022] Open
Abstract
Invisibility is often thought to occur because of the low-level limitations of the visual system. For example, it is often assumed that backward masking renders a target invisible because the visual system is simply too slow to resolve the target and the mask separately. Here, we propose an alternative explanation in which invisibility is a goal rather than a limitation and occurs naturally when making sense out of the plethora of incoming information. For example, we present evidence that (in)visibility of an element can strongly depend on how it groups with other elements. Changing grouping changes visibility. In addition, we will show that features often just appear to be invisible but are in fact visible in a way the experimenter is not aware of.
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Affiliation(s)
- Michael H Herzog
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
| | - Frouke Hermens
- School of Psychology, University of Aberdeen Aberdeen, UK
| | - Haluk Oğmen
- Department of Electrical and Computer Engineering, Center for NeuroEngineering and Cognitive Science, University of Houston Houston, TX, USA
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10
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A neural model of visual figure-ground segregation from kinetic occlusion. Neural Netw 2013; 37:141-64. [DOI: 10.1016/j.neunet.2012.09.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 09/19/2012] [Accepted: 09/20/2012] [Indexed: 11/19/2022]
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11
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Ağaoğlu MN, Herzog MH, Oğmen H. Non-retinotopic feature processing in the absence of retinotopic spatial layout and the construction of perceptual space from motion. Vision Res 2012; 71:10-7. [PMID: 22929811 DOI: 10.1016/j.visres.2012.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 07/18/2012] [Accepted: 08/14/2012] [Indexed: 11/29/2022]
Abstract
The spatial representation of a visual scene in the early visual system is well known. The optics of the eye map the three-dimensional environment onto two-dimensional images on the retina. These retinotopic representations are preserved in the early visual system. Retinotopic representations and processing are among the most prevalent concepts in visual neuroscience. However, it has long been known that a retinotopic representation of the stimulus is neither sufficient nor necessary for perception. Saccadic Stimulus Presentation Paradigm and the Ternus-Pikler displays have been used to investigate non-retinotopic processes with and without eye movements, respectively. However, neither of these paradigms eliminates the retinotopic representation of the spatial layout of the stimulus. Here, we investigated how stimulus features are processed in the absence of a retinotopic layout and in the presence of retinotopic conflict. We used anorthoscopic viewing (slit viewing) and pitted a retinotopic feature-processing hypothesis against a non-retinotopic feature-processing hypothesis. Our results support the predictions of the non-retinotopic feature-processing hypothesis and demonstrate the ability of the visual system to operate non-retinotopically at a fine feature processing level in the absence of a retinotopic spatial layout. Our results suggest that perceptual space is actively constructed from the perceptual dimension of motion. The implications of these findings for normal ecological viewing conditions are discussed.
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Affiliation(s)
- Mehmet N Ağaoğlu
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77024-4005, USA
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12
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Herzog MH, Otto TU, Ogmen H. The fate of visible features of invisible elements. Front Psychol 2012; 3:119. [PMID: 22557985 PMCID: PMC3338119 DOI: 10.3389/fpsyg.2012.00119] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 04/01/2012] [Indexed: 11/13/2022] Open
Abstract
To investigate the integration of features, we have developed a paradigm in which an element is rendered invisible by visual masking. Still, the features of the element are visible as part of other display elements presented at different locations and times (sequential metacontrast). In this sense, we can "transport" features non-retinotopically across space and time. The features of the invisible element integrate with features of other elements if and only if the elements belong to the same spatio-temporal group. The mechanisms of this kind of feature integration seem to be quite different from classical mechanisms proposed for feature binding. We propose that feature processing, binding, and integration occur concurrently during processes that group elements into wholes.
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Affiliation(s)
- Michael H Herzog
- Laboratory of Psychophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL) Lausanne, Switzerland
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13
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Wu B, Klatzky RL, Stetten GD. Mental visualization of objects from cross-sectional images. Cognition 2012; 123:33-49. [PMID: 22217386 DOI: 10.1016/j.cognition.2011.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 11/16/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
We extended the classic anorthoscopic viewing procedure to test a model of visualization of 3D structures from 2D cross-sections. Four experiments were conducted to examine key processes described in the model, localizing cross-sections within a common frame of reference and spatiotemporal integration of cross sections into a hierarchical object representation. Participants used a hand-held device to reveal a hidden object as a sequence of cross-sectional images. The process of localization was manipulated by contrasting two displays, in situ vs. ex situ, which differed in whether cross sections were presented at their source locations or displaced to a remote screen. The process of integration was manipulated by varying the structural complexity of target objects and their components. Experiments 1 and 2 demonstrated visualization of 2D and 3D line-segment objects and verified predictions about display and complexity effects. In Experiments 3 and 4, the visualized forms were familiar letters and numbers. Errors and orientation effects showed that displacing cross-sectional images to a remote display (ex situ viewing) impeded the ability to determine spatial relationships among pattern components, a failure of integration at the object level.
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Affiliation(s)
- Bing Wu
- Cognitive Science and Engineering Program, Arizona State University, Mesa, AZ 85212, USA.
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14
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Aydın M, Herzog MH, Oğmen H. Barrier effects in non-retinotopic feature attribution. Vision Res 2011; 51:1861-71. [PMID: 21767561 DOI: 10.1016/j.visres.2011.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 06/17/2011] [Accepted: 06/27/2011] [Indexed: 11/30/2022]
Abstract
When objects move in the environment, their retinal images can undergo drastic changes and features of different objects can be inter-mixed in the retinal image. Notwithstanding these changes and ambiguities, the visual system is capable of establishing correctly feature-object relationships as well as maintaining individual identities of objects through space and time. Recently, by using a Ternus-Pikler display, we have shown that perceived motion correspondences serve as the medium for non-retinotopic attribution of features to objects. The purpose of the work reported in this manuscript was to assess whether perceived motion correspondences provide a sufficient condition for feature attribution. Our results show that the introduction of a static "barrier" stimulus can interfere with the feature attribution process. Our results also indicate that the barrier stops feature attribution based on interferences related to the feature attribution process itself rather than on mechanisms related to perceived motion.
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Affiliation(s)
- Murat Aydın
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77024-4005, USA
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15
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Boi M, Oğmen H, Herzog MH. Motion and tilt aftereffects occur largely in retinal, not in object, coordinates in the Ternus-Pikler display. J Vis 2011; 11:11.3.7. [PMID: 21389102 DOI: 10.1167/11.3.7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Recent studies have shown that a variety of aftereffects occurs in a non-retinotopic frame of reference. These findings have been taken as strong evidence that remapping of visual information occurs in a hierarchic manner in the human cortex with an increasing magnitude from early to higher levels. Other studies, however, failed to find non-retinotopic aftereffects. These experiments all relied on paradigms involving eye movements. Recently, we have developed a new paradigm, based on the Ternus-Pikler display, which tests retinotopic vs. non-retinotopic processing without the involvement of eye movements. Using this paradigm, we found strong evidence that attention, form, and motion processing can occur in a non-retinotopic frame of reference. Here, we show that motion and tilt aftereffects are largely retinotopic.
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Affiliation(s)
- Marco Boi
- Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Switzerland.
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The faux, fake, forged, false, fabricated, and phony: Problems for the independence of similarity-based theories of concepts. Behav Brain Sci 2010; 33:215. [DOI: 10.1017/s0140525x10000385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractSome things in our environment are not what they seem, and they provide a challenge to theories of concepts that emphasize similarity. Section 1 of my commentary explores a dilemma this situation creates for Machery. Section 2 describes a more general problem for prototype and exemplar theories. Section 3 locates a place for similarity-based concepts, and indicates an alternative to Machery's thesis.
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Otto TU, Ogmen H, Herzog MH. Feature integration across space, time, and orientation. J Exp Psychol Hum Percept Perform 2010; 35:1670-86. [PMID: 19968428 DOI: 10.1037/a0015798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The perception of a visual target can be strongly influenced by flanking stimuli. In static displays, performance on the target improves when the distance to the flanking elements increases-presumably because feature pooling and integration vanishes with distance. Here, we studied feature integration with dynamic stimuli. We show that features of single elements presented within a continuous motion stream are integrated largely independent of spatial distance (and orientation). Hence, space-based models of feature integration cannot be extended to dynamic stimuli. We suggest that feature integration is guided by perceptual grouping operations that maintain the identity of perceptual objects over space and time.
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Affiliation(s)
- Thomas U Otto
- Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Federale de Lausanne, Switzerland.
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Öğmen H, Herzog MH. The Geometry of Visual Perception: Retinotopic and Non-retinotopic Representations in the Human Visual System. PROCEEDINGS OF THE IEEE. INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS 2010; 98:479-492. [PMID: 22334763 PMCID: PMC3277856 DOI: 10.1109/jproc.2009.2039028] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Geometry is closely linked to visual perception; yet, very little is known about the geometry of visual processing beyond early retinotopic organization. We present a variety of perceptual phenomena showing that a retinotopic representation is neither sufficient nor necessary to support form perception. We discuss the popular "object files" concept as a candidate for non-retinotopic representations and, based on its shortcomings, suggest future directions for research using local manifold representations. We suggest that these manifolds are created by the emergence of dynamic reference-frames that result from motion segmentation. We also suggest that the metric of these manifolds is based on relative motion vectors.
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Affiliation(s)
- Haluk Öğmen
- Department of Electrical & Computer Engineering and Center for NeuroEngineering & Cognitive Science, University of Houston, Houston, TX 77204-4005 USA (phone: 713-743-4428; fax: 713-743-4444
| | - Michael H. Herzog
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Abstract
When a figure moves behind a stationary narrow slit, observers often report seeing the figure as a whole, a phenomenon called slit viewing or anorthoscopic perception. Interestingly, in slit viewing, the figure is perceived compressed along the axis of motion. As with other perceptual distortions, it is unclear whether the perceptual space in the vicinity of the slit or the representation of the figure itself undergoes compression. In a psychophysical experiment, we tested these two hypotheses. We found that the percept of a stationary bar, presented within the slit, was not distorted even when at the same time a circle underwent compression by moving through the slit. This result suggests that the compression of form results from figural rather than from space compression. In support of this hypothesis, we found that when the bar was perceptually grouped with the circle, the bar appeared compressed. Our results show that, in slit viewing, the distortion occurs at a non-retinotopic level where grouped objects are jointly represented.
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Affiliation(s)
- Murat Aydin
- Department of Electrical and Computer Engineering, University of Houston, Houston, TX 77024-4005, USA.
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Visual masking and the dynamics of human perception, cognition, and consciousness A century of progress, a contemporary synthesis, and future directions. Adv Cogn Psychol 2008; 3:1-8. [PMID: 20517493 PMCID: PMC2864989 DOI: 10.2478/v10053-008-0009-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2007] [Accepted: 04/20/2007] [Indexed: 11/20/2022] Open
Abstract
The 1990s, the “decade of the brain,” witnessed major advances in the study of
visual perception, cognition, and consciousness. Impressive techniques in
neurophysiology, neuroanatomy, neuropsychology, electrophysiology, psychophysics
and brain-imaging were developed to address how the nervous system transforms
and represents visual inputs. Many of these advances have dealt with the
steady-state properties of processing. To complement this “steady-state
approach,” more recent research emphasized the importance of dynamic aspects of
visual processing. Visual masking has been a paradigm of choice for more than a
century when it comes to the study of dynamic vision. A recent workshop
(http://lpsy.epfl.ch/VMworkshop/), held in Delmenhorst, Germany,
brought together an international group of researchers to present
state-of-the-art research on dynamic visual processing with a focus on visual
masking. This special issue presents peer-reviewed contributions by the workshop
participants and provides a contemporary synthesis of how visual masking can
inform the dynamics of human perception, cognition, and consciousness.
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Abstract
Most theories of visual masking focus prima-rily on the temporal aspects of
visual information processing, strongly neglecting spatial factors. In recent
years, however, we have shown that this position is not tenable. Spatial aspects
cannot be neglected in metacontrast, pattern and un-masking. Here, we review
these results.
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Aydın M, Herzog MH, Öğmen H. Perceived speed differences explain apparent compression in slit viewing. Vision Res 2008; 48:1603-12. [DOI: 10.1016/j.visres.2008.04.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 04/23/2008] [Accepted: 04/23/2008] [Indexed: 11/28/2022]
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