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EDUCATION:

Bachelor (Licenciatura) in Psychology, University of Oviedo (Spain), 1997.

Master (Proyecto de Investigaci��n) in Psychology, University of Oviedo (Spain), 1999.
Title of thesis: "Genesis of Images and Symbols in the field of Perception: the explanations of Herman von Helmholtz".
(Original title: "La g��nesis de la imagen y el s��mbolo en el ��mbito de la Percepci��n: las explicaciones de H. von Helmholtz").
Short description: Helmholtz is a crucial figure to understand the development of the field of psychology. This work reviews Helmholtz's theories of space perception. We understand Helmholtz's work as an advance in the "naturalization" of Kant's notion of Transcendental Subject (S��nchez, 1995). Against Kant's view of space as an "a priori" form of sensibility, we argue that both, Helmholtz's theory of eye movements and his explanations of space perception, play a central role in his attempts to provide an ontogenetic understanding of perceptual processes: space is empirically constructed through a functional coordination of eye movements, retinal stimulations and various sorts of tactile sensations. Therefore, spatial perception cannot be reduced to anatomical and physiological structures.
In collaboration with Tom��s R. Fern��ndez and Jose Carlos S��nchez (University of Oviedo).

Ph.D. (Tesis Doctoral) in Psychology, University of Oviedo (Spain), 2003.
Title: "Limitations of the concept of Representation in explaining visual perception: Change Blindness, Implicit Memory and Eye Movements".
(Original title: "Limitaciones del concepto de Representaci��n en la Percepci��n Visual: Ceguera al Cambio, Retenci��n Impl��cita y Movimientos Oculares").
Description: When considering visual perception, there are different models that have been suggested. Some of these models consider that the main function of perception is the production of a global representation of the visual scene (cognitive theories are an example of this kind). On the other hand, there exist a few models that criticize a representational interpretation of perceptual processes (like Gibson's). Experimental results in what is called the Change Blindness phenomena suggest, as No��, Pessoa and Thompson (2000) have pointed out, that there are some philosophical problems in these representational explanations, because they define perception as a passive process. However, some of the alternative models that have been proposed to explain perception as a kind of action are problematic as well, because they do not consider the role of memory in the organization of actions (as in O'Regan and No��, 2001). In this work we critically review the main experiments on Change Blindness, and compare them with other results, like those found in Contextual Cueing and Priming of Pop-Out experiments, that seem to suggest that we are able to easily learn and implicitly remember some of the properties of the visual scene that are stable. To analyze the active dimension of visual perception we ran a group of experiments that recorded eye and hand movements while subjects were copying a three-dimensional model in a virtual environment. In these experiments the spatial position of some of the pieces needed for the task was changed during subject's eye movements (what produces change blindness), but the properties of the environment were kept stable during the task (so contextual cueing was possible). It was found that gaze was often directed to the position that a specific piece occupied before a change was introduced (its old position). At the same time, the introduction of changes produced an increase in the number of eye fixations that subjects made while locating the next piece to be moved, but did not affect fixation duration. In my Doctoral Thesis these results are discussed with respect to the relevance of memory in the understanding of action, the idea of different levels of consciousness in perceptual processes and the relations between attention and the purpose of actions.
In collaboration with Tom��s R. Fern��ndez (University of Oviedo) and Mary M. Hayhoe (University of Rochester).

Posdoctoral Education (2002-2005): Perception for action, motor control, purposive actions.
Description: Many studies of motor control analyze movement kinematics using very simple tasks that imply a movement to a single target. This strategy, although useful, also leads authors to understand actions as sequences of individual movements. However there is evidence that suggests that actions may not be controlled in this manner. Movements towards single targets are faster than movements that continue to a second target (one-target advantage, Adam et al., 2000). Also the kinematics of the first movement of a sequence of two depends on the difficulty of the second part (e.g. Rand et al., 1997). These results suggest that sequences of movements are treated as single actions and planned before movement initiation considering the properties of the different targets. During my postdoctoral stay at the Erasmus MC, Rotterdam I collaborated with Eli Brenner and Jeroen B.J. Smeets in analyzing the differences between planning of movements and on-line control. Our main strategy was to manipulate the targets of the action or the objects of the environment and explore how much time subjects needed to adjust their movements in response to it. We have completed several experiments that examine how people respond to changes that occur while they are moving to the first target of a sequence. Subjects moved a stylus across a digitising tablet, from a specified starting point to two targets in succession. On some trials (20%) the properties of either the first or the second target changed, as soon as the subject started to move. When the size of the first target changed the subjects slowed down the first segment of their movements. Even the peak velocity, which was only about 150 ms after the change in size, was lower. Beside this fast response to the change itself, the dwell time at the first target was also affected: its duration increased after the change. Changing the size and position of the second target did not influence the first segment of the movement, but also increased the dwell time. Taken together, these results suggest that the whole sequence is treated as one action, which can be corrected if the properties of any of the targets change. The precise nature and timing of the correction depends on how the change influences the task. We have completed a new experiment that examines how a movement changes if we add a subsequent movement or cancel the following movement. We are also running some experiments to determine whether responses to changes that affect an obstacle are as fast as those to changes that affect the target of the movement. We have also designed a cube with two force sensors that we want to use to examine whether grip positions and grasping forces change depending on the purpose of the movement.

Maria Pilar Aivar Rodriguez

Profesor Contratado Doctor

Facultad de Psicologia

Universidad Autonoma de Madrid

Madrid, Spain

Mail to: M Pilar Aivar

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