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Perceiving transformed movements when using tools.

Saturday, October 01st,   2011 [08:30 - 10:30]

SY_11. Perceiving transformed movements when using tools

Sutter, C. 1 & Suelzenbrueck, S. 2

1 Work and Cognitive Psychology, RWTH Aachen University, Germany
2 Project Group Transformed Movements, IfADo - Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany

Modern technologies progressively create workplaces in which movement execution and observation are spatially separated. Challenging workplaces in which users act with technical equipment in a distant space are, for instance, laparoscopic surgery, teleoperation or virtual reality. When using a tool, proprioceptive/tactile feedback from the moving hand and visual feedback from the moving effective part of the tool do often not correspond or are even in conflict. This discrepancy would be a constant source of interference if proprioceptive/tactile and visual feedback would be equally important for controlling actions. The present symposium is aimed at discussing the underlying cognitive processes that enables us to cope successfully with sensorimotor transformations. Theoretical and empirical evidence will be presented from different perspectives and using various methodologies in behavioral and clinical studies: 1) the role of mechanical reasoning for the successful utilization of tools as well as the idea that humans spontaneously represent objects as potential tools to enhance their body's abilities will be discussed. 2) Experimental evidence will show that tool actions are controlled - to a greater extent - by distant action effects than by our body effects. This seems to be advantageous, as it allows for a much wider range of flexible sensorimotor adaptations and maybe more important, it gives us the feeling of being in control. 3) Furthermore, constraints of the visual predominance and its consequences on (re)mapping body space and distant space are outlined.



SY_11.1 - Why do we use tools? Insights from neuropsychology and experimental psychology

Osiurak, F.

Laboratoire d’Etude des Mécanismes Cognitifs (EA 3082), Université Lumière Lyon 2, Lyon, France

Although humans are not unique in using tools, they are special in having established a culture which the use and manufacture of tools is a universal feature. Only humans possess a vast repertoire of tool-use skills, make one tool to create another, or spontaneously engage in tool use activities. A certain number of attempts have been made to model how humans perform tool behaviour. But, another important question, which has received very little attention from psychologists, is why humans use tools so frequently and
spontaneously? In this talk, I shall address this intriguing issue. More specifically, after discussing studies in neuropsychology demonstrating that tool use might be supported by the ability to reason about object’s physical properties, I shall present recent evidence that people may quite spontaneously represent objects as potential tools to enhance their body’s abilities.

SY_11.2 - Using tools to shape body and space representations

Farnè, A. 1, 2 , Cardinali, L. 1, 2 , Brozzoli, C. 3 & Roy, A. C. 4

1 INSERM U1028, CNRS UMR 5292, Lyon Neuroscience Research Centre, ImpAct Team, F-69500 Lyon, France
2 University Claude Bernard Lyon I, F-69000 Lyon, France
3 Department of Neuroscience, Brain, Body & Self lab, Karolinska Institut, SE-17177 Stockholm, Sweden
4 CNRS UMR 5230 Laboratoire sur le Langage le Cerveau et la Cognition, Lyon Neuroscience Centre, F-69500 Bron, France

Along the evolutionary history, humans have reached a high level of sophistication in the way they interact with the environment. We are able to modify, adapt and shape the world around us according to our needs. One important step in this process has been the introduction of tools, enabling humans to go beyond the boundaries of their physical possibilities. Behind the complex phenomenon of phylogenetic development of tool-use, we will focus some “low-level” aspects of cognition that highlight how tool-use plays a causal role in shaping both spatial and bodily representations. Indeed, updating representations of the body and its action-space is essential for efficient motor control during development and skilful tool-use in the adult life. The almost one-century-old hypothesis that tool-use induces plastic changes resulting in the tool being incorporated in the body representation is widely accepted, and intuitive enough to become a popular notion. Here, we will critically review the evidence supporting this hypothesis on the basis of the effects of tool-use on multisensory coding of peripersonal space, as documented in the normal and pathological brain. Recent findings and ongoing work from our laboratory will be presented and discussed as evidence supporting the incorporation of a tool in the body representation. In particular, we will present several experiments that reveal the effects of tool-use both on the kinematics of hand movements and the localisation of somatosensory stimuli on the body surface, as well as the conditions that are necessary for these effects to be manifest. These findings speak in favour of genuine, tooluse-dependent plasticity of the body representation for the control of action.

SY_11.3 - Impaired tool use following brain damage

Hermsdörfer, J. , Randerath, J. , Goldenberg, G. , Stadler, W. & Dieler, A.

Department of Sport and Health Science, Technische Universität München

Lesions of the left hemisphere following a stroke may lead to impaired use of common tools and objects in activities of daily living. Deficits of ADL performance is one manifestation of apraxia that is also characterized by errors in pantomime or imitation. To decipher the underlying deficit, we examined the relationship between performance with the tool in hand in a natural-like situation (condition Use), with the tool only (Demo), and without the tool (pure pantomime: Panto). Performance of 23 patients with left brain damage (LBD), 10 patients with right brain damage (RBD), and control subjects were tested on the non-paretic ipsilesional hand. The tasks “hammering” und “scooping” were conducted in the condition Panto, Demo, and Use. Video analyses were performed as well as kinematic analyses of arm and hand trajectories. Evaluation of movement errors revealed a clear prevalence of movement abnormalities in LBD patients and in the condition Panto as typically observed in apraxia. Compared to healthy controls the performance of LBD patients was however also impaired in the Use condition and factor analysis suggested communalities of the error patterns across the conditions. Similarly, the kinematic analyses revealed a gradient of errors from Panto to Use in LBD patients with significant correlations between characteristic movement variables such as movement direction and maximum velocity. The results show that in apraxic patients the lack of context is detrimental and presence of affordances is beneficial in using tools. A common factor seems to underlay aspects of the movement deficit independent of the condition of execution. The factor may be related to deficient tool manipulation knowledge, impaired mechanical reasoning, working memory deficits, errors of tool transformations (of the virtual or the real tool) and/or errors in considering the dynamic demands of the movement. Since variability is high and dissociations exist it is believed that multiple processes contribute to apraxia.

SY_11.4 - Perception of and adjustments to gain changes

Suelzenbrueck, S. 1 , Sutter, C. 2 & Ladwig, S. 2

1 Project Group Transformed Movement, IfADo - Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
2 Work and Cognitive Psychology, RWTH Aachen University, Germany

The ideomotor principle holds that actors select, initiate and execute movements by activating the anticipatory codes of the movements' sensory effects. These may be representations of body-related effects and/or representations of more distal effects. When using tools effects in body space and distant space often do not correspond or are even in conflict. Previous studies have demonstrated that distal action effects dominate action control, while body-related effects play a minor role. In this talk we present a line of experiments in which we address the conditions and limitations of the distal predominance in action control. In a closed loop task of sensorimotor control different gains perturbed the relation between hand movements on a digitizer tablet and cursor movements on a display. Concerning motor control the data showed that the human brain adapt to small changes in visuomotor gain without being aware of the changes in gain or in one's own movement. When provided with explicit information about the occurrence of gain changes adjustments were stronger than implicit adjustments. The larger adjustments observed with cued gain changes resulted from both explicit and implicit motor adjustments occurring at the same time. We further observed that participants were generally extremely uncertain about the trajectory of their hand movements when using such tools. We discuss whether the low awareness of one's own movements originates from an insufficient quality of the humans' tactile and proprioceptive system or from an insufficient spatial reconstruction of this information in memory.

SY_11.5 - Does tool use extend peripersonal space?

Holmes, N. P.

School of Psychology & Clinical Language Sciences, University of Reading, Reading, UK

The idea that tools are extensions of our body is an fascinating idea that appears in artistic, literary, philoshical, and scientific work. In the last fifteen years, this idea has been studied extensively in the cognitive neurosciences, with evidence from molecular, neurophysiological, neuroimaging, neuropsychological, and behavioural fields. In my talk, I will briefly review the main sources of evidence for and against the hypothesis that tool use extends a neural representation of the space surrounding the hands. I will argue both that the original neurophysiological data in monkeys do not show that tool use extends the representation of nearby space, and that subsequent behavioural data from humans are consistent with multiple alternative explanations. I conclude that, after fifteen years, clear support for the hypothesis that tool use extends peripersonal space is still lacking.

SY_11.6 - Visual-haptic integration in tool use

Watt, S. J. 1 , Diedrichsen, J. 2 & Takahashi, C. 1

1 School of Psychology, Bangor University, Wales
2 Institute of Cognitive Neuroscience, UCL, London, England

We often see and feel the same object simultaneously, and so estimates of object properties are available from vision and haptics. Here we explore whether the brain integrates information from these two sensory modalities when we use tools to interact with objects. In normal grasping, the brain does not select one sensory modality and ignore the other. Instead, information from both signals is integrated (Ernst & Banks, 2002), and exploiting the redundancy in multiple signals results in better performance than would be possible from either signal alone. For visual-haptic integration to be effective, however, the brain must solve a 'correspondence problem': it should integrate information referring to the same object, and it should NOT integrate information referring to different objects. This could be achieved by considering the similarity of signals in the two sensory modalities (Ernst, 2007; Körding et al., 2007). For example, if there is a large conflict between two size estimates, or they are separated in space, it is unlikely that they originate from the same object. Tools complicate this, however, because they systematically change the relationship between (seen) object size and the opening of the hand, as well as perturbing the spatial locations of each signal. We report several experiments showing that the brain does take these changes into account when using a tool: vision and haptics are integrated near-optimally, but only when it is appropriate to do so. We argue, therefore, that the brain combines visual and haptic information, not based on the similarity of sensory stimuli, but based on the similarity of the distal causes of stimuli, taking into account the dynamics and geometry of tools. We speculate that this is achieved by altering the forward model used to control arm movements, rather than by a specialised mechanism for tool use.

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