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1.
Exp Brain Res ; 186(4): 619-27, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18214451

RESUMO

This experiment investigated the roles of haptic and auditory contact information for the control and execution of reaching to grasp augmented (physical plus graphic) and virtual (graphic only) objects of different sizes using a tool. Haptic contact information was present when grasping augmented objects only. In half of the trials, auditory cues were provided when contact was made between the tip of the tool and the target object. Transport and grasp kinematics, as well as on spatial errors at the end of the movement were examined. Providing auditory cues at contact led to faster movements; moreover, when haptic information was not available (when grasping virtual objects), auditory cues improved spatial accuracy. Movement times increased as the object size decreased for the augmented objects, when haptic information was available, and also for the virtual objects when auditory contact cues were provided, thus following Fitts' law. However, movement times were similar for all object sizes when neither haptic nor auditory contact information was provided. These results emphasize the importance of contact information when grasping with a tool, and the benefits of auditory contact cues for improving performance.


Assuntos
Sinais (Psicologia) , Força da Mão/fisiologia , Desempenho Psicomotor/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adulto , Fenômenos Biomecânicos , Humanos , Movimento/fisiologia , Tempo de Reação/fisiologia
2.
Exp Brain Res ; 180(1): 69-84, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17242914

RESUMO

Two experiments investigated the effects of haptic, auditory and graphic contact cues on reaching to grasp augmented objects (physical and graphic) and virtual objects (graphic only) of various sizes. In Experiment 1, auditory contact cues were presented either to enhance or to replace natural haptic contact cues in grasping. In Experiment 2, graphic contact cues were presented alone or in combination with auditory cues, and were provided either to enhance or to replace haptic contact information. Visual information of the hand was not available. Experiment 1 showed that enhancing haptic contact information with redundant auditory cues (augmented object) led to faster movement times than haptic cues alone. When haptic information was not available (virtual object), it could be replaced to some extent by auditory contact cues. In Experiment 2 movement times were fastest when both auditory and graphic cues were provided, and slowest when no contact cues were provided. Further, movement times were scaled to target width when reaching to grasp augmented objects, thus following Fitts' law. In contrast, movement times showed a less pronounced decrease with increasing object size for virtual objects. However, even in the absence of haptic information, movement times showed a more pronounced scaling to object size when auditory contact cues were provided. These results emphasize the importance of contact information, especially haptic and auditory information, for planning and control of reaching and grasping.


Assuntos
Sinais (Psicologia) , Força da Mão/fisiologia , Desempenho Psicomotor/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Movimento , Tempo de Reação/fisiologia , Fatores de Tempo
3.
Exp Brain Res ; 179(3): 443-56, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17136520

RESUMO

The size-weight illusion induced by visually perceived sizes was reexamined to investigate whether this illusion is a sensory based or cognitive-based phenomenon. A computer-augmented environment was utilized to manipulate visual size information of target objects independently of their haptic information. Two physical cubes of equal mass (30.0 g) and size (3.0 x 3.0 x 3.0 cm) were suspended in parallel by wires attached to small graspable rings, in order to keep haptically obtained information constant between lifts. Instead of directly seeing each physical cube, subjects viewed 3D graphics of a cube with a wire and a ring that were precisely superimposed onto each physical cube. Seventeen subjects vertically lifted these augmented cubes, one after the other, by grasping the attached rings, and then reported their perception of cube heaviness. The graphical size of a comparison cube pseudo randomly varied for every comparison from 1.0 x 1.0 x 1.0 to 9.0 x 9.0 x 9.0 cm, while that of a standard cube remained constant (5.0 x 5.0 x 5.0 cm). Results indicated that the size-weight illusion frequently and systematically occurred for all the subjects such that when the comparison cube was relatively smaller than the standard cube, it was perceived to be heavier, and vice versa. As the size difference increased between the standard cube and the comparison cube, more subjects experienced the illusion, and vice versa. Follow-up tests showed occurrence of the size-weight illusion was significantly correlated with subject's sensitivity to discriminate weight, but not with sensitivity to discriminate visual size. Results suggest that the size-weight illusion induced by only visual size cues in an augmented environment is sensory based, and depends on an individual's integrated perception based on multimodal sensory information.


Assuntos
Cognição/fisiologia , Sinais (Psicologia) , Ilusões/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Adulto , Retroalimentação/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Testes Neuropsicológicos , Estimulação Luminosa
4.
Stud Health Technol Inform ; 119: 586-91, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16404127

RESUMO

An approach to enhance navigation task performance is to integrate sensory guidance (virtual fixtures) into a virtual training system. To evaluate the effects of adding virtual fixtures to skill acquisition, 32 subjects were required to use a PHANToM input device, to transport a virtual object through a computer generated 3-D graphic maze. Subjects practiced navigation under 4 conditions: the maze was augmented with either a graphic fixture (G), attractive force field (F), both graphic and force field (GF), or no (N) virtual fixture. Fifteen practice trials were given before subjects were transferred to a situation with no virtual fixtures. Results showed that the implementation of the force field assisted task performance during practice; however, it failed to show positive transfer effects. In contrast, adding a graphic fixture to the virtual maze helped subjects to define the optimal pathway throughout navigation, which facilitated skill acquisition.


Assuntos
Simulação por Computador , Destreza Motora , Interface Usuário-Computador , Educação Médica , Humanos
5.
Exp Brain Res ; 163(2): 173-87, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15761722

RESUMO

The goal of the present study was to investigate how grip forces are applied when transferring stable control of an object from one person to another. We asked how grip forces would be modified by the passer to (1) control for inertial forces as the object was transported toward the receiver and (2) control for the impending perturbation when the receiver made contact with the object. Twelve volunteers worked in pairs during this experiment. One partner, playing the role of passer, transported an object with embedded load cells forward or held the object at an interception location. The second partner, playing the role of receiver, waited at an interception location or reached toward the passed object. Kinematic results indicated that while passers performed a stereotypical movement, receivers were sensitive to the motion of the object as they reached to make contact. Grip force results indicated that passers' grip forces and grip/load force ratios were variable on a trial-to-trial basis, suggesting that a refined internal model of the passing task was not achieved within the timeframe of the experiment. Furthermore, a decoupling of the temporal and magnitude characteristics of the grip and inertial forces was noted in conditions where passers transported the object toward the receiver. During object transfer, it was noted that passers used visual feedback-based anticipatory control to precisely time initial grip force release, while somatosensory control was used by both the passer and receiver to precisely coordinate transfer rate.


Assuntos
Força da Mão/fisiologia , Mãos/fisiologia , Movimento/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Cognição/fisiologia , Retroalimentação , Feminino , Humanos , Masculino , Propriocepção/fisiologia , Desempenho Psicomotor/fisiologia , Percepção do Tempo/fisiologia , Tato/fisiologia , Suporte de Carga/fisiologia
6.
Stud Health Technol Inform ; 85: 334-40, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-15458111

RESUMO

One of the key components of any training environment for surgical education is a method that can be used for assessing surgical skills. Traditionally, defining such a method has been difficult and based mainly on observations. However, through advances in modeling techniques and computer hardware and software, such methods can now be developed using combined visual and haptic rendering of a training scene. This paper presents some ideas on how metrics may be defined and used in the assessment of surgical skills in a virtual laparoscopic training environment.


Assuntos
Competência Clínica/estatística & dados numéricos , Simulação por Computador , Avaliação Educacional/estatística & dados numéricos , Retroalimentação , Cirurgia Geral/educação , Laparoscopia/estatística & dados numéricos , Tato , Interface Usuário-Computador , Animais , Humanos , Sistema Métrico , Fotografação , Desempenho Psicomotor , Software , Suínos , Gravação em Vídeo
7.
Ergonomics ; 45(15): 1091-102, 2002 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-12569044

RESUMO

Augmented reality allows changes to be made to the visual perception of object size even while the tangible components remain completely unaltered. It was, therefore, utilized in a study whose results are being reported here to provide the proper environment required to thoroughly observe the exact effect that visual change to object size had on programming fingertip forces when objects were lifted with a precision grip. Twenty-one participants performed repeated lifts of an identical grip apparatus to a height of 20 mm, maintained each lift for 8 seconds, and then replaced the grip apparatus on the table. While all other factors of the grip apparatus remained unchanged, visual appearance was altered graphically in a 3-D augmented environment. The grip apparatus measured grip and load forces independently. Grip and load forces demonstrated significant rates of increase as well as peak forces as the size of graphical images increased; an aspect that occurred in spite of the fact that extraneous haptic information remained constant throughout the trials. By indicating a human tendency to rely - even unconsciously - on visual input to program the forces in the initial lifting phase, this finding provides further confirmation of previous research findings obtained in the physical environment; including the possibility of extraneous haptic effects (Gordon et al. 1991a, Mon-Williams and Murray 2000, Kawai et al. 2000). The present results also suggest that existing knowledge concerning human manipulation tasks in the physical world may be applied to an augmented environment where the physical objects are enhanced by computer generated visual components.


Assuntos
Força da Mão , Interface Usuário-Computador , Percepção Visual , Adolescente , Adulto , Gráficos por Computador , Ergonomia , Feminino , Humanos , Remoção , Masculino , Estados Unidos
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