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Translational biological motion : speed perception, time-to-contact and time-to-passage estimations; Movimento biológico em translação : percepção de velocidade e estimativa do tempo até ao contacto e tempo para a intersecção

Mouta, Sandra Maria Caldas da Silva
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 06/10/2009 ENG
Relevância na Pesquisa
56.37%
Tese de doutoramento em Psicologia Experimental e Ciências Cognitivas; The development of norms and policies for the increase of traffic safety must consider all aspects of the road environment as well all the associated human factors. In order to analyse and prevent traffic conflicts, it is crucial to investigate how the available information on road environments is processed. Traffic conflicts are frequently caused by the late detection of other road users and pedestrians are especially vulnerable in those situations (Rumar, 1990). Knowing which variables affect the pedestrians’ detection and collision estimation can give an important contribution to the increase of road safety and injury prevention on vulnerable road users. Therefore, the main aim of this research was to understand how available information extracted from translational biological motion pattern is processed. From the studies of Johansson (1973, 1976) is generally assumed that the human visual system is highly prepared to extract meaningful information from biological motion patterns (Cutting & Kozlowski, 1977; Dittrich, 1993; Pollick, Kay, Heim, & Stringer, 2005; Troje, 2002, 2005). However, almost all classical studies on biological motion perception focus on the detection and recognition of specific patterns...

The benefit of multisensory integration with biological motion signals

Mendonça, Catarina; Santos, Jorge A.; López-Moliner, Joan
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
Relevância na Pesquisa
65.95%
Assessing intentions, direction, and velocity of others is necessary for most daily tasks, and such information is often made available by both visual and auditory motion cues. Therefore, it is not surprising our great ability to perceive human motion. Here, we explore the multisensory integration of cues of biological motion walking speed. After testing for audiovisual asynchronies (visual signals led auditory ones by 30ms in simultaneity temporal windows of 76.4ms), in the main experiment, visual, auditory, and bimodal stimuli were compared to a standard audiovisual walker in a velocity discrimination task. Results in variance reduction conformed to optimal integration of congruent bimodal stimuli across all subjects. Interestingly, the perceptual judgments were still close to optimal for stimuli at the smallest level of incongruence. Comparison of slopes allows us to estimate an integration window of about 60ms, which is smaller than that reported in audiovisual speech.

Temporal Integration in the perception of biological motion

Henriques, Bruno Armando Aragão
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 31/01/2013 ENG
Relevância na Pesquisa
56.39%
Tese de doutoramento em Psicologia (área de especilização em Psicologia Experimental e Ciências Cognitivas); The visual perception of motion is crucial to human survival. The information provided by objects in motion and by our own movements allows for an effective adaptation to the environment, especially in the interaction with others. The perception of humans in motion is so critical that our capacity to perceive it appears to be innate (Fox & McDaniel, 1982; Pavlova et al., 2003). The studies on biological motion met a great development in the last forty years, enhanced by the work of Johansson (1973), who developed a paradigm characterized by the use of impoverished visual stimuli - point-light walkers. The research with point-light walkers showed that we can extract relevant information from human motion, allowing for instance the distinction between different kinds of actions (Dittrich, 1993; Mather & Murdoch, 1994). Several authors have shown that we can not only differentiate actions, but also perceive social information, such as gender (Barclay, Cutting, & Kozlowski, 1978), identity (Cutting & Kozlowski, 1977), emotions (Dittrich et al. 1996), or deception and vulnerability (Runeson & Frykholm, 1983). Although many of the spatial characteristics of biological motion perception are sufficiently studied...

Percepção de velocidade do movimento biológico : mais resistente ao fenômeno de interferência?; Perception of speed in biological motion : more resistant to interference?

Mouta, Sandra; Santos, Jorge A.
Fonte: Pontifícia Universidade Católica de Campinas Publicador: Pontifícia Universidade Católica de Campinas
Tipo: Artigo de Revista Científica
Publicado em 09/08/2011 POR
Relevância na Pesquisa
56.26%
O sistema visual humano é frequentemente referido como altamente preparado para extrair informação relevante de padrões de movimento biológico. Nesse sentido, este estudo analisa o efeito de contraste na percepção de velocidade. Os participantes realizaram o julgamento de velocidade numa situação na qual dois point-light walkers simultâneos foram apresentados com diferentes contrastes relativamente ao fundo e com diferentes velocidades de translação. Na Experiência 1, o movimento de translação biológico canônico foi comparado com o movimento de translação rígido, enquanto na Experiência 2 ele foi comparado com o movimento de translação biológico invertido. O padrão biológico canônico apresenta maior taxa de erro, tempos de reação mais elevados e maior vulnerabilidade ao efeito de contraste na percepção da velocidade do que o padrão rígido. No entanto, não foram encontradas diferenças significativas entre o estímulo canônico e o invertido. A Experiência 3 foi implementada com o objetivo de se controlar o papel das pistas posicionais na tarefa de julgamento de velocidade. Os pontos iniciais e finais da trajetória foram combinados de modo a que os point-light walkers mais rápidos e os mais lentos pudessem terminar o ensaio numa posição relativamente mais avançada ou atrasada. Apesar desta variação...

Functional neuroanatomy of biological motion perception in humans

Vaina, Lucia M.; Solomon, Jeffrey; Chowdhury, Sanjida; Sinha, Pawan; Belliveau, John W.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66.08%
We used whole brain functional MRI to investigate the neural network specifically engaged in the recognition of “biological motion” defined by point-lights attached to the major joints and head of a human walker. To examine the specificity of brain regions responsive to biological motion, brain activations obtained during a “walker vs. non-walker” discrimination task were compared with those elicited by two other tasks: (i) non-rigid motion (NRM), involving the discrimination of overall motion direction in the same “point-lights” display, and (ii) face-gender discrimination, involving the discrimination of gender in briefly presented photographs of men and women. Brain activity specific to “biological motion” recognition arose in the lateral cerebellum and in a region in the lateral occipital cortex presumably corresponding to the area KO previously shown to be particularly sensitive to kinetic contours. Additional areas significantly activated during the biological motion recognition task involved both, dorsal and ventral extrastriate cortical regions. In the ventral regions both face-gender discrimination and biological motion recognition elicited activation in the lingual and fusiform gyri and in the Brodmann areas 22 and 38 in superior temporal sulcus (STS). Along the dorsal pathway...

Perception of biological motion without local image motion

Beintema, J. A.; Lappe, M.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 16/04/2002 EN
Relevância na Pesquisa
66.29%
A vivid perception of the moving form of a human figure can be obtained from a few moving light points on the joints of the body. This is known as biological motion perception. It is commonly believed that the perception of biological motion rests on image motion signals. Curiously, however, some patients with lesions to motion processing areas of the dorsal stream are severely impaired in image motion perception but can easily perceive biological motion. Here we describe a biological motion stimulus based on a limited lifetime technique that tests the perception of a moving human figure in the absence of local image motion. We find that subjects can spontaneously recognize a moving human figure in displays without local image motion. Their performance is very similar to that for classic point-light displays. We also find that tasks involving the discrimination of walking direction or the coherence of a walking figure can be performed in the absence of image motion. Thus, although image motion may generally aid processes such as segmenting figure from background, we propose that it is not the basis for the percept of biological motion. Rather, we suggest biological motion is derived from dynamic form information on body posture evolving over time.

Impairments of Biological Motion Perception in Congenital Prosopagnosia

Lange, Joachim; de Lussanet, Marc; Kuhlmann, Simone; Zimmermann, Anja; Lappe, Markus; Zwitserlood, Pienie; Dobel, Christian
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 12/10/2009 EN
Relevância na Pesquisa
66.23%
Prosopagnosia is a deficit in recognizing people from their faces. Acquired prosopagnosia results after brain damage, developmental or congenital prosopagnosia (CP) is not caused by brain lesion, but has presumably been present from early childhood onwards. Since other sensory, perceptual, and cognitive abilities are largely spared, CP is considered to be a stimulus-specific deficit, limited to face processing. Given that recent behavioral and imaging studies indicate a close relationship of face and biological-motion perception in healthy adults, we hypothesized that biological motion processing should be impaired in CP. Five individuals with CP and ten matched healthy controls were tested with diverse biological-motion stimuli and tasks. Four of the CP individuals showed severe deficits in biological-motion processing, while one performed within the lower range of the controls. A discriminant analysis classified all participants correctly with a very high probability for each participant. These findings demonstrate that in CP, impaired perception of faces can be accompanied by impaired biological-motion perception. We discuss implications for dedicated and shared mechanisms involved in the perception of faces and biological motion.

Comparing Biological Motion Perception in Two Distinct Human Societies

Pica, Pierre; Jackson, Stuart; Blake, Randolph; Troje, Nikolaus F.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/12/2011 EN
Relevância na Pesquisa
66.17%
Cross cultural studies have played a pivotal role in elucidating the extent to which behavioral and mental characteristics depend on specific environmental influences. Surprisingly, little field research has been carried out on a fundamentally important perceptual ability, namely the perception of biological motion. In this report, we present details of studies carried out with the help of volunteers from the Mundurucu indigene, a group of people native to Amazonian territories in Brazil. We employed standard biological motion perception tasks inspired by over 30 years of laboratory research, in which observers attempt to decipher the walking direction of point-light (PL) humans and animals. Do our effortless skills at perceiving biological activity from PL animations, as revealed in laboratory settings, generalize to people who have never before seen representational depictions of human and animal activity? The results of our studies provide a clear answer to this important, previously unanswered question. Mundurucu observers readily perceived the coherent, global shape depicted in PL walkers, and experienced the classic inversion effects that are typically found when such stimuli are turned upside down. In addition, their performance was in accord with important recent findings in the literature...

An asymmetry of translational biological motion perception in schizophrenia

Hastings, Caitlín N. M.; Brittain, Philip J.; ffytche, Dominic H.
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 16/07/2013 EN
Relevância na Pesquisa
66.1%
Background: Biological motion perception is served by a network of regions in the occipital, posterior temporal, and parietal lobe, overlapping areas of reduced cortical volume in schizophrenia. The atrophy in these regions is assumed to account for deficits in biological motion perception described in schizophrenia but it is unknown whether the asymmetry of atrophy found in previous studies has a perceptual correlate. Here we look for possible differences in sensitivity to leftward and rightward translation of point-light biological motion in data collected for a previous study and explore its underlying neurobiology using functional imaging.

Neural correlates of coherent and biological motion perception in autism

Koldewyn, Kami; Whitney, David; Rivera, Susan M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66.22%
Recent evidence suggests those with autism may be generally impaired in visual motion perception. To examine this, we investigated both coherent and biological motion processing in adolescents with autism employing both psychophysical and fMRI methods. Those with autism performed as well as matched controls during coherent motion perception but had significantly higher thresholds for biological motion perception. The autism group showed reduced posterior Superior Temporal Sulcus (pSTS), parietal and frontal activity during a biological motion task while showing similar levels of activity in MT+/V5 during both coherent and biological motion trials. Activity in MT+/V5 was predictive of individual coherent motion thresholds in both groups. Activity in dorsolateral prefrontal cortex (DLPFC) and pSTS was predictive of biological motion thresholds in control participants but not in those with autism. Notably, however, activity in DLPFC was negatively related to autism symptom severity. These results suggest that impairments in higher-order social or attentional networks may underlie visual motion deficits observed in autism.

Biological Motion Perception Is Affected by Age and Cognitive Style in Children Aged 8–15

Ghanouni, Parisa; Memari, Amir Hossein; Shayestehfar, Monir; Moshayedi, Pouria; Gharibzadeh, Shahriar; Ziaee, Vahid
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
66.21%
The current paper aims to address the question of how biological motion perception in different social contexts is influenced by age or also affected by cognitive styles. We examined developmental changes of biological motion perception among 141 school children aged 8–15 using point-light displays in monadic and dyadic social contexts. Furthermore, the cognitive styles of participants were investigated using empathizing-systemizing questionnaires. Results showed that the age and empathizing ability strongly predicted improvement in action perception in both contexts. However the systemizing ability was an independent predictor of performance only in monadic contexts. Furthermore, accuracy of action perception increased significantly from 46.4% (SD = 16.1) in monadic to 62.5% (SD = 11.5) in dyadic social contexts. This study can help to identify the roles of social context in biological motion perception and shows that children with different cognitive styles may present different biological motion perception.

A new technique for generating disordered point-light animations for the study of biological motion perception

Kim, Jejoong; Jung, Eunice L.; Lee, Sang-Hun; Blake, Randolph
Fonte: The Association for Research in Vision and Ophthalmology Publicador: The Association for Research in Vision and Ophthalmology
Tipo: Artigo de Revista Científica
Publicado em 25/08/2015 EN
Relevância na Pesquisa
66.26%
Studies of biological motion perception often use stimuli depicting human actions portrayed via point-light (PL) displays. Typically, counterpart, or control, stimuli for PL biological motion are created by spatially scrambling motion trajectories of individual PL dots. Depending on the purpose of the study, however, this procedure may be inappropriate as a foil for genuine PL animations, because spatial scrambling not only disrupts coherent motion activity but also eliminates pair-wise motion relationships among dots and, unless corrected, alters the spatial spread of PL dot motions. We introduce a new technique for producing perturbed PL animations, called pair-wise shuffled motion, that preserves the elementary features of biological motion in spatial and motion energy domains and only disrupts the specific sense of global, coherent perception of biological motion. First we describe the procedure for creating pair-wise shuffled motion sequences. Next we compare unperturbed PL animations to pair-wise shuffled motion, to spatially scrambled motion, and to spatially constrained scrambled motion in terms of spatial distributions of the dots, spatiotemporal amplitude spectra derived from Fourier analysis of those sequences, and space-time motion energy associated with those perturbed animations. We then show that the results from those analyses generalize to a large family of PL animations...

Deficient biological motion perception in schizophrenia: results from a motion noise paradigm

Kim, Jejoong; Norton, Daniel; McBain, Ryan; Ongur, Dost; Chen, Yue
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
96.36%
Background:: Schizophrenia patients exhibit deficient processing of perceptual and cognitive information. However, it is not well-understood how basic perceptual deficits contribute to higher level cognitive problems in this mental disorder. Perception of biological motion, a motion-based cognitive recognition task, relies on both basic visual motion processing and social cognitive processing, thus providing a useful paradigm to evaluate the potentially hierarchical relationship between these two levels of information processing. Methods: In this study, we designed a biological motion paradigm in which basic visual motion signals were manipulated systematically by incorporating different levels of motion noise. We measured the performances of schizophrenia patients (n = 21) and healthy controls (n = 22) in this biological motion perception task, as well as in coherent motion detection, theory of mind, and a widely used biological motion recognition task. Results: Schizophrenia patients performed the biological motion perception task with significantly lower accuracy than healthy controls when perceptual signals were moderately degraded by noise. A more substantial degradation of perceptual signals, through using additional noise, impaired biological motion perception in both groups. Performance levels on biological motion recognition...

Biologically Plausible Neural Model for the Recognition of Biological Motion and Actions

Giese, Martin Alexander; Poggio, Tomaso
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Formato: 26 p.; 3562724 bytes; 2540946 bytes; application/postscript; application/pdf
EN_US
Relevância na Pesquisa
75.9%
The visual recognition of complex movements and actions is crucial for communication and survival in many species. Remarkable sensitivity and robustness of biological motion perception have been demonstrated in psychophysical experiments. In recent years, neurons and cortical areas involved in action recognition have been identified in neurophysiological and imaging studies. However, the detailed neural mechanisms that underlie the recognition of such complex movement patterns remain largely unknown. This paper reviews the experimental results and summarizes them in terms of a biologically plausible neural model. The model is based on the key assumption that action recognition is based on learned prototypical patterns and exploits information from the ventral and the dorsal pathway. The model makes specific predictions that motivate new experiments.

Frühe bilaterale, subkortikale, parieto-occipitale Läsionen und ihr Einfluss auf die motorische Entwicklung sowie die Wahrnehmung biologischer Bewegung am Beispiel der periventrikulären PVL bei ehemaligen Frühgeborenen; Periventricular leukomalacia in former preterms a model for early bilateral, subcortical, parieto-occipital lesions and their influence on motor development and perception of biological motion

Böhm, Helene Selina
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
86.15%
Frühgeborene, die zwischen der 27. und 33. Schwangerschaftswoche geboren werden, haben ein erhöhtes Risiko für Gehirnläsionen, typischerweise einer periventriculären Leukomalazie (PVL). Diese führt je nach Grösse und Lokalisation zu unterschiedlichen neurologischen Symptomen (spatische Cerbralparese (CP), Störung der visuellen Wahrnehmung, psychomotorische Retardierung...). Aufgrund der typischen parieto-occipitalen Lokalisation ist es möglich bei diesen Kindern Fragestellungen zu frühen subkortikalen Läsionen und deren Einfluss auf die motorische (nähe zur Pyramidenbahn) und visuelle (Nähe zur primären und sekundären Sehrinde und zum dorsalen pathway) Entwicklung zu untersuchen. Im Rahmen dieser Studie wurde zum einen die Frage untersucht, ob es einen Zusammenhang zwischen motorischer Funktion sowie Größe und Lokalisation der PVL im Bereich der Pyramidenbahn gibt. Dazu wurden insgesamt 32 Kinder zwischen 13 und 16 Jahren ,13 davon ehemalige Frühgeborene ( geboren in der 27-34 Schwangerschaftswoche (SSW) ) mit PVL, und 19 Kontrollen (10 ehemalige Frühgeborene ohne PVL (28-33 SSW) und neun Reifgeborene) ohne neurologische Auffälligkeiten, neurologisch und mit dem MRI untersucht. Bei der MRI Untersuchung wurde auf semicoronaren MRI-Rekonstruktionen entlang anatomischer Landmarken entsprechend der Somatotopie im präcentralen Gyrus und in der Capsula interna die Schwere der Schädigung der Pyramidenbahn durch die PVL bestimmt. Das Gesamtvolumen der weissen Substanz diente als Maß für die globale Schwere der PVL. Es fand sich eine starke Korrelation zwischen der Einschränkung der motorischen Funktion der vier Extremitäten und der Schädigung der Pyramidenbahn durch die PVL. Es fand sich keine Korrelation zwischen der motorischen Funktion und dem Volumen der weißen Substanz Des weiteren wurde die Fragestellung untersucht ob ehemalige Frühgeborene mit periventrikulärer Leukomalazie in der Wahrnehmung maskierter biologischer Bewegung beeinträchtigt sind. Dazu wurde bei 28 Kindern ( 19 davon Frühgeboren...

Effects of anxiety on perceptual biases for ambiguous biological motion stimuli

Heenan, Adam
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
76.1%
Biological motion stimuli, depicted as orthographically projected point-light or stick-figure walkers, do not contain any information about their orientation in depth. The projections of such stimuli, therefore, provide the same visual information when oriented towards the viewer as when oriented away. Even though this is the case, naïve observers display a bias to perceive the facing-towards percept more often. Some researchers have speculated that this facing-the-viewer bias may exist for sociobiological reasons. That is, mistaking another human as retreating when they are actually approaching could potentially have more severe consequences than the opposite error. This theory implies that the facing-towards percept of a biological motion stimulus is potentially more threatening. Measures of anxiety and the facing-the-viewer bias should therefore be related, as researchers have consistently found that anxious individuals display an attentional bias towards more threatening stimuli. In our first experiment, we demonstrated that individuals with greater anxiety do indeed have greater facing-the-viewer biases, and that this relationship is mediated by inhibitory ability (Chapter 2). As our first experiment was correlational in nature...

Local invariants for biological motion perception

Chang, Dorita Hue Fung
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
86.31%
Observers can retrieve the facing direction of a walker from point-light displays that are devoid of structure-from-motion information and retain solely local motion signals. This ability is orientation-dependent and relies on the motions representing the feet of the agent. The experiments described here were designed to investigate visual sensitivity to local cues contained in biological motion. Initial experiments revealed that local biological motion carries information about animacy in addition to the agent’s facing direction in an orientation-dependent manner (Chapter 2). The mechanism underlying the perception of local biological motion can be dissociated from that underlying the retrieval of global structure-from-motion information according to characteristics such as sensitivity to learning and noise (Chapter 3). Further experiments revealed that the orientation-dependency for perceiving local biological motion is carried by vertical acceleration in the foot’s motion (Chapter 4). The importance of acceleration for biological motion perception raises the need to achieve a better understanding of acceleration sensitivity across various parameters such as stimulus size. To this end, Chapter 5 showed that acceleration thresholds for perceiving a linearly accelerating stimulus scale according to mean velocity as predicted by size invariance and are inversely proportional to stimulus duration. An important role for acceleration for the perception of biological motion was further corroborated by findings in an evolutionarily guided psychophysical search for the adequate local motion...

Components of Biological Motion Perception

SAUNDERS, Daniel Robert
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
86.22%
Biological motion perception, defined as the ability to retrieve information from minimal displays of animal motion, has often been discussed as though it represents a single mechanism. However, depending on the task and details of the stimuli, there have been divergent results as to whether this ability is primarily based on motion or form processing, whether it relies more on local or global information, and whether the knowledge that is applied is learned or innate. These results can be reconciled by a multi-component framework, with five major components: local motion invariant processing, structure-from-motion, figure-ground segregation, action categorization, and style recognition. Several experiments are reported that are motivated by this framework. To investigate the sensitivity of the visual system to local motion invariants, performance was tested on a direction discrimination and a detection task with a point-light walker based on real motion-capture data or a synthetic walker created by Cutting (Chapter 2). When the walkers were displayed normally, performance was equal for both stimuli. However, when the walkers were spatially scrambled, the direction could only be determined for the natural walker, demonstrating that the invariant is found in subtle features of the local motion trajectories. Another experiment examined the difference in attentional distribution due to the task requirements (Chapter 3). Participants looked more often at the feet in a direction task than they did in a gender task...

The Interpretation of Biological Motion

Hoffman, D.D.; Flinchbaugh, B.E.
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Formato: 22 p.; 6654072 bytes; 4775914 bytes; application/postscript; application/pdf
EN_US
Relevância na Pesquisa
66.02%
The term biological motion has been coined by G. Johansson (1973) to refer to the ambulatory patterns of terrestrial bipeds and quadripeds. In this paper a computational theory of the visual perception of biological motion is proposed. The specific problem addressed is how the three dimensional structure and motions of animal limbs may be computed from the two dimensional motions of their projected images. It is noted that the limbs of animals typically do not move arbitrarily during ambulation. Rather, for anatomical reasons, they typically move in single planes for extended periods of time. This simple anatomical constraint is exploited as the basis for utilizing a "planarity assumption" in the interpretation of biological motion. The analysis proposed is: (1) divide the image into groups of two or three elements each; (2) test each group for pairwise-rigid planar motion; (3) combine the results from (2). Fundamental to the analysis are two 'structure from planar motion' propositions. The first states that the structure and motion of two points rigidly linked and rotating in a plane is recoverable from three orthographic projections. The second states that the structure and motion of three points forming two hinged rods constrained to move in a plane is recoverable from two orthographic projections. The psychological relevance of the analysis and possible interactions with top down recognition processes are discussed.

Perception of biological motion in visual agnosia

Huberle, Elisabeth; Rupek, Paul; Lappe, Markus; Karnath, Hans-Otto
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 28/08/2012 EN
Relevância na Pesquisa
56.31%
Over the past 25 years, visual processing has been discussed in the context of the dual stream hypothesis consisting of a ventral (“what”) and a dorsal (“where”) visual information processing pathway. Patients with brain damage of the ventral pathway typically present with signs of visual agnosia, the inability to identify and discriminate objects by visual exploration, but show normal perception of motion perception. A dissociation between the perception of biological motion and non-biological motion has been suggested: perception of biological motion might be impaired when “non-biological” motion perception is intact and vice versa. The impact of object recognition on the perception of biological motion remains unclear. We thus investigated this question in a patient with severe visual agnosia, who showed normal perception of non-biological motion. The data suggested that the patient's perception of biological motion remained largely intact. However, when tested with objects constructed of coherently moving dots (“Shape-from-Motion”), recognition was severely impaired. The results are discussed in the context of possible mechanisms of biological motion perception.