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Perception and action

Friday, September 30th,   2011 [17:20 - 19:20]

PS_1.010 - Dissociation between perception and action in pseudoneglect

Massen, C. 1 , Rieger, M. . 2 & Sülzenbrück, S. . 1

1 Leibniz Research Centre for Working Environment and Human Factors
2 Frankfurt University

An important question in visual cognition is whether processing visual input for perceptual judgment differs in a fundamental way from processing visual input to guide one’s actions. Many studies, e.g. on visual illusions, have supported this view, but have typically focused on simple action requirements like grasping for an object. In this study, we investigated dissociations between perception and action using more complex tool-use actions. In a line bisection task, participants had to either mark the centre of a line with a pencil or cut the line in two halves using a pair of scissors. Results indicated the typical leftward bias (pseudoneglect) in the pencil task, but no such bias in the scissors task. These results indicate that the distinctiveness of processing visual input for action can be demonstrated in tasks other than grasping and support the notion of functional differences between vision for perception and vision for action.

PS_1.011 - The effects of direction and identity of pointing hand stimulus on manual key press responses

Nishimura, A. 1, 2 , Ariga, A. 3 & Michimata, C. 1

1 Department of Psychology. Sophia University. Tokyo, Japan.
2 JSPS. Tokyo, Japan.
3 Department of Psychology. Rissho University. Tokyo, Japan.

We investigated the effects of direction (left, right), identity (left hand, right hand), and finger (index finger, little finger) of a task-irrelevant pointing hand stimulus on bimanual left/right key press responses with index or little fingers. Participants made left or right key press response according to the color of a centrally presented target. Before the onset of the target, a pointing hand stimulus, which was irrelevant to the task, was briefly presented at the center of the screen. The spatial correspondence effect based on the pointing direction and the response key position was larger for the hand stimulus of index finger pointing than of little finger pointing, indicating the spatial compatibility effect based on others’ intention. The stimulus-response hand correspondence exerted a positive effect when the responses were made with little fingers, but the effect was negative when the responses were made with index fingers. The results indicate the importance of controllability of the effector in automatic imitation. The present study showed multiple automatic influences induced by perception of others’ pointing hand on our own action.

PS_1.012 - When articulation influences finger imitation: An event-related dual-task study

Nakayama, M. 1, 2 & Saito, S. 1

1 Graduate school of education. Kyoto University. Kyoto, Japan.
2 Japan Society for the Promotion of Science. Tokyo, Japan

The cognitive functions of language and imitation are both unique to humans. Moreover, the brain regions responsible for these functions (i.e., Broca’s area) overlap somewhat. Kühn and Brass (2008) recently investigated the functional commonality of articulation and imitation using a dual-task technique. They showed that concurrent articulation facilitated finger imitation in a simple response task, which lead to the assumption that Broca’s area was pre-activated. The present study explored the temporal dynamics of this facilitation effect. Specifically, we manipulated the relative timing (0 ± 250 ms) of articulation and imitation, requiring that participants pace their articulations (i.e., event-related dual tasking). An additional experimental manipulation involved the presence of an articulation preceding stimulus onset. Our results showed a facilitative effect of finger imitation, which was strongly affected by the relative timing, but not by the presence, of the preceding additional articulation. The present study highlighted the mechanism underlying the interaction and commonality of two cognitive functions, language and imitation.

PS_1.013 - The role of oculo-motor coordination in affordance

Ottoboni, G. 1 , Borghi, A. M. 2 & Tessari, A. 1

1 Department of Psychology, University of Bologna, Italy
2 Institute of Cognitive Sciences and Technologies, National Research Council, Rome, Italy

Recently Ellis and Tucker (2000) proposed that “micro-affordances” are a consequence of object-based attention. Behavioural studies on affordances typically use asymmetrical common-use objects. To study affordance aside from the asymmetrical confound, we used a new symmetrical object (8-shaped object) whose orientation was manipulated to get the graspable part closer to participants’ hands or eyes. In Experiment 1 the entire object was coloured, in Experiment 2, only the central part of the object was. Participants (adults and children) answered according to the colours by pressing one of two lateralized keys. We had expected affordance effect for both the objects and groups, however, no effect arose in Experiment 1, maybe because attention was devoted over the whole object. In Experiment 2, instead, both the groups showed the effect but only for the graspable part close to participants' eyes and not for that close to their hand: children showed the effect for the lower part of the object, adults for the upper part of it. The result suggests that affordances are not automatic but task-dependent. Most importantly, they indicate that the ocular components plays a crucial role allowing the affordance to emerge.

PS_1.014 - Handle-to-hand correspondence effects: Disambiguating Location Coding and Affordance Activation Accounts

Pellicano, A. & Binkofski, F.

University Hospital RWTH Aachen, Germany

Reaction times to object-tool stimuli are often faster when the task-irrelevant handle location corresponds with the response location than when it does not. According to a location coding account, object spatial coding depends on the location of its salient portion. This perceived asymmetry facilitates same-sided responses compared to opposite ones. Alternatively, an affordance activation account states that this effect depends on the activation of grasping actions towards the handle with the corresponding hand. The aim of this study was to provide disambiguating evidence whether handle-to-hand correspondence effects are produced by simple location coding or more complex affordance activation patterns. We selected pictures of tools with one salient, but non-graspable, tip and one opposite graspable, but non-salient, tip (non-jutting handle). When the graspable portion was not also visually salient, no correspondence effect was observed between its left/rightward orientation and the left/right responding hand. Conversely, a spatial correspondence effect was produced between the orientation of the salient portion and the responding hand. Results clearly support the location coding account: performance was influenced by the simple spatial coding of a visually salient property of the object. Accurate control of saliency will be crucial for future investigations on affordance effects.

PS_1.015 - Assimilation-error in tool use as a question of reference system

Ladwig, S. , Sutter, C. , Müsseler, J. , Wendler, K. & Bade, F.

Department of work and cognitive psychology. RWTH Aachen University. Aachen. Germany.

In tool use non-corresponding proximal and distal action effects appear to have solid impact on motor performance. Recent findings show motor behaviour assimilates towards perturbed visual feedback. In the present experiments we investigated if and to what extend these deviations will also occur in a cross-modal task of sensorimotor control. Different gains for the x-axis perturbed the relation between hand movements on the digitizer tablet and cursor movements on a display. The covered hand movement was held constant while the cursor amplitude was shorter, equal or longer, and vice versa in the other condition. Participants were asked to replicate either their initial hand amplitude (hand judgement) or the displayed cursor amplitude (display judgement) without gaining visual feedback. First, the replicated hand amplitudes varied in accordance with the non-corresponding distal effect, showing the expected solid impact of visual distractors. Furthermore, deviations remarkably increased in the cross-modal task. When participants were asked to replicate the initially seen cursor movement judgements assimilated by 56% towards the proximal distractor. To sum up, in the cross-modal task kinaesthetic/proprioceptive feedback dominated action control and overruled the visual predominance.

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