This paper discusses both a dissociation view and a dynamic view with respect to the study of vol... more This paper discusses both a dissociation view and a dynamic view with respect to the study of voluntary, goal-directed behavior. The dissociation view builds on the recently reintroduced ideomotor principle, and conceives of clearly dissociated and hierarchical roles for the planning and control of action. The dynamic view has a more integral and dynamic conception of how planning, control, and
Two experiments investigated how 3-year-old children select a tool to perform a manual task, with... more Two experiments investigated how 3-year-old children select a tool to perform a manual task, with a focus on their perseverative parameter choices for the various relationships involved in handling a tool: the actor-to-tool relation and the tool-to-target relation (topology). The first study concerned the parameter value for the tool-to-target relation by asking how children use a cane for either pushing an object further away (exclosure; outside the hook) or pulling an object nearby (enclosure; inside the hook). The second study concerned the parameter value for the hand-to-tool relation by assessing the hand used for grasping a spoon to feed a puppet. Results from both studies showed that on the first trial, choices were driven by task information. However, when the task switched from pulling to pushing or from left hand to right hand, or vice versa, children persevered with the choice they made during the 4 previous trials. Results are discussed in terms of the dynamical field modeling work of Esther Thelen and her colleagues. Our findings underscore Thelen's hypotheses that: (a) the action-selection process is a dynamic affair, affected by multiple influences at different time scales and its own intrinsic dynamics; and (b) that perseverative behavior is a general phenomenon that is neither indicative for a specific period in the development, nor for a particular task. Similarly, we argue that the presence (or absence) of causal understanding emerges from the action-selection process, rather than determining this process.
This paper describes an experiment in which the performance of cane walkers with the traditional ... more This paper describes an experiment in which the performance of cane walkers with the traditional straight long cane and a redesigned cane, the curved cane, was compared. The curved cane has a curve where the tip touches the ground. Participants were 18 experienced cane walkers who were totally blind. The aspects of cane walking that were investigated included obstacle detection, drop-off (slope) detection and walking speed. The performance with both canes was investigated in two different ways: (1) by means of constructed courses in which objective measures of cane walking were derived; and (2) by means of more qualitative measures based on the participants' experiences with the curved cane during a 3-week try-out period. Results showed that obstacle-detection was significantly better with the curved cane, whereas drop-off detection and walking speed were comparable for the two canes. The participants' experiences mirrored these results.
We asked what rod properties affected children's reaching range. Children, 2 to ... more We asked what rod properties affected children's reaching range. Children, 2 to 4 years old, held a rod (length 10-60 cm) with the tip in the air, walked toward a toy on a table, chose a place to stop, and displaced the toy with the rod's tip. In 2 experiments rod length, mass, and mass distribution were manipulated to determine whether and how geometric and kinetic properties affected chosen distance and posture. Chosen distance depended only on the length of the rod. Postures were affected by length and mass properties of the rod. Not all ...
Tool use consists of at least two coupled phases of activities, involving multi-step problem solv... more Tool use consists of at least two coupled phases of activities, involving multi-step problem solving. It therefore provides an interesting window on the development of planning in goal-directed behavior. This study investigated 2-year-olds' and 3-year-olds' hand use in picking up and subsequently using a tool for displacing a target-object towards a specified goal location. The children had to use a stick (Experiment 1; N = 41 in total) or a cane (hooked stick) that was lying in varying starting orientations (Experiment 2; N = 32 in total). Age differences were found in the way goal-related information in combination with toolrelated information influenced the choice of which hand to use in different phases of the task. A view on action planning is developed as a dynamic action-selection process for which actions to take. This process integrates factors that are internal to the child's action system (e.g. motor preferences and dexterity) with external (i.e. sensory) sources of information.
The haptic exploratory procedures that eight Congenitally blind infants aged 8-24 months used to ... more The haptic exploratory procedures that eight Congenitally blind infants aged 8-24 months used to explore a gradient surface texture were investigated. Exploration of the gradient texture was examined over five sessions with 2 weeks between sessions, followed after 1 week by a sixth session, in which exploration of the gradient texture was compared to exploration of two other textures. Results showed that the infants have a wide range of exploratory strategies available and that the older infants can use these strategies in a specific manner. Results are discussed with reference to current ideas about the exploratory possibilities of congenitally blind infants. Use of texture in the stimulation of exploration of blind infants is discussed. Child: care, health and development VOWME 23 NLJMBBR 3 I997 PAGES 247-264 0 1997 Blackwell Science Lrd 250
... Parts of this article were written while Raoul Bongers was supported by Grant 575-23-013 from... more ... Parts of this article were written while Raoul Bongers was supported by Grant 575-23-013 from the Foundation for Behavioural and Educational Sciences of the Netherlands Organization for Scientific Research, awarded to Claire Michaels. ...
The significance of texture as a source of information in tactual space perception was studied us... more The significance of texture as a source of information in tactual space perception was studied using a linear positioning task. A spatial texture gradient, whose elements changed with position and distance, a homogeneous raised-element pattern and a smooth surface were used. Participants had to reproduce locations and distances on these surfaces under various conditions. In active conditions, participants moved their indexfinger across the surface. In passive conditions, the texture was moved beneath the indexfinger of the participant. In conditions with equal movement speed, movement speeds' of criterion and reproduction phase were matched, in conditions with unequal movement speed, they did not match. The largest errors were obtained for the combined passive movement-unequal movement speed conditions. In these conditions, differences between textures were visible for signed and unsigned errors, indicating that textures may differ in the cutaneous specification of distance and location.
This paper discusses both a dissociation view and a dynamic view with respect to the study of vol... more This paper discusses both a dissociation view and a dynamic view with respect to the study of voluntary, goal-directed behavior. The dissociation view builds on the recently reintroduced ideomotor principle, and conceives of clearly dissociated and hierarchical roles for the planning and control of action. The dynamic view has a more integral and dynamic conception of how planning, control, and
Two experiments investigated how 3-year-old children select a tool to perform a manual task, with... more Two experiments investigated how 3-year-old children select a tool to perform a manual task, with a focus on their perseverative parameter choices for the various relationships involved in handling a tool: the actor-to-tool relation and the tool-to-target relation (topology). The first study concerned the parameter value for the tool-to-target relation by asking how children use a cane for either pushing an object further away (exclosure; outside the hook) or pulling an object nearby (enclosure; inside the hook). The second study concerned the parameter value for the hand-to-tool relation by assessing the hand used for grasping a spoon to feed a puppet. Results from both studies showed that on the first trial, choices were driven by task information. However, when the task switched from pulling to pushing or from left hand to right hand, or vice versa, children persevered with the choice they made during the 4 previous trials. Results are discussed in terms of the dynamical field modeling work of Esther Thelen and her colleagues. Our findings underscore Thelen's hypotheses that: (a) the action-selection process is a dynamic affair, affected by multiple influences at different time scales and its own intrinsic dynamics; and (b) that perseverative behavior is a general phenomenon that is neither indicative for a specific period in the development, nor for a particular task. Similarly, we argue that the presence (or absence) of causal understanding emerges from the action-selection process, rather than determining this process.
This paper describes an experiment in which the performance of cane walkers with the traditional ... more This paper describes an experiment in which the performance of cane walkers with the traditional straight long cane and a redesigned cane, the curved cane, was compared. The curved cane has a curve where the tip touches the ground. Participants were 18 experienced cane walkers who were totally blind. The aspects of cane walking that were investigated included obstacle detection, drop-off (slope) detection and walking speed. The performance with both canes was investigated in two different ways: (1) by means of constructed courses in which objective measures of cane walking were derived; and (2) by means of more qualitative measures based on the participants' experiences with the curved cane during a 3-week try-out period. Results showed that obstacle-detection was significantly better with the curved cane, whereas drop-off detection and walking speed were comparable for the two canes. The participants' experiences mirrored these results.
We asked what rod properties affected children's reaching range. Children, 2 to ... more We asked what rod properties affected children's reaching range. Children, 2 to 4 years old, held a rod (length 10-60 cm) with the tip in the air, walked toward a toy on a table, chose a place to stop, and displaced the toy with the rod's tip. In 2 experiments rod length, mass, and mass distribution were manipulated to determine whether and how geometric and kinetic properties affected chosen distance and posture. Chosen distance depended only on the length of the rod. Postures were affected by length and mass properties of the rod. Not all ...
Tool use consists of at least two coupled phases of activities, involving multi-step problem solv... more Tool use consists of at least two coupled phases of activities, involving multi-step problem solving. It therefore provides an interesting window on the development of planning in goal-directed behavior. This study investigated 2-year-olds' and 3-year-olds' hand use in picking up and subsequently using a tool for displacing a target-object towards a specified goal location. The children had to use a stick (Experiment 1; N = 41 in total) or a cane (hooked stick) that was lying in varying starting orientations (Experiment 2; N = 32 in total). Age differences were found in the way goal-related information in combination with toolrelated information influenced the choice of which hand to use in different phases of the task. A view on action planning is developed as a dynamic action-selection process for which actions to take. This process integrates factors that are internal to the child's action system (e.g. motor preferences and dexterity) with external (i.e. sensory) sources of information.
The haptic exploratory procedures that eight Congenitally blind infants aged 8-24 months used to ... more The haptic exploratory procedures that eight Congenitally blind infants aged 8-24 months used to explore a gradient surface texture were investigated. Exploration of the gradient texture was examined over five sessions with 2 weeks between sessions, followed after 1 week by a sixth session, in which exploration of the gradient texture was compared to exploration of two other textures. Results showed that the infants have a wide range of exploratory strategies available and that the older infants can use these strategies in a specific manner. Results are discussed with reference to current ideas about the exploratory possibilities of congenitally blind infants. Use of texture in the stimulation of exploration of blind infants is discussed. Child: care, health and development VOWME 23 NLJMBBR 3 I997 PAGES 247-264 0 1997 Blackwell Science Lrd 250
... Parts of this article were written while Raoul Bongers was supported by Grant 575-23-013 from... more ... Parts of this article were written while Raoul Bongers was supported by Grant 575-23-013 from the Foundation for Behavioural and Educational Sciences of the Netherlands Organization for Scientific Research, awarded to Claire Michaels. ...
The significance of texture as a source of information in tactual space perception was studied us... more The significance of texture as a source of information in tactual space perception was studied using a linear positioning task. A spatial texture gradient, whose elements changed with position and distance, a homogeneous raised-element pattern and a smooth surface were used. Participants had to reproduce locations and distances on these surfaces under various conditions. In active conditions, participants moved their indexfinger across the surface. In passive conditions, the texture was moved beneath the indexfinger of the participant. In conditions with equal movement speed, movement speeds' of criterion and reproduction phase were matched, in conditions with unequal movement speed, they did not match. The largest errors were obtained for the combined passive movement-unequal movement speed conditions. In these conditions, differences between textures were visible for signed and unsigned errors, indicating that textures may differ in the cutaneous specification of distance and location.
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Papers by A. Smitsman