Frank Zaal | University of Groningen (original) (raw)

Papers by Frank Zaal

Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Human Movement Science, Aug 1, 2010

Both in the catching and grasping component of prehension, the hand opens and closes before hand-... more Both in the catching and grasping component of prehension, the hand opens and closes before hand-object contact is made. The initiation of hand closure has to be coordinated with the time course of the decrease of the distance between the hand and the target object, i.e., with the reaching component in prehension or the approach of the target in catching. The authors investigated if this initiation of hand closure could be explained by a common control. For this purpose, they fitted the dynamic timing model to data from the two tasks. In both tasks, participants were asked to get hold of an object approaching along the table top at a constant velocity. In the prehension task, participants could reach out to grasp the object; in the catching task, they were required to keep their hand stationary. In comparison with other accounts, the dynamic timing model performed best in explaining the data. The model proved adequate for the prehension task but not for the current catching task.

HAL (Le Centre pour la Communication Scientifique Directe), 2017

Ecological Psychology, Jun 23, 2022

Human Movement Science, Jun 1, 2012

Neuroscience Letters, 2010

Point-to-point movements constrained to the horizontal plane are generally straight, although the... more Point-to-point movements constrained to the horizontal plane are generally straight, although they exhibit slight deviations from straightness. Unconstrained horizontal movements (i.e., movements where the hand is lifted) are more curved in their projection onto the horizontal plane than constrained movements. It has been argued that this difference in horizontal curvature is due to differences in the space in which the movements were planned (joint space versus work space, respectively). The current study challenged this explanation. We found that horizontal curvature of constrained movements increased when moving over a round surface compared to moving over a flat surface and when friction was low compared to when friction was high. Because all these movements were constrained movements this suggests that the earlier reported differences in horizontal curvature between constrained and unconstrained movements may not originate from a difference in the movements' planning space. The discussion addresses how factors related to planning and factors related to biomechanics may contribute to the magnitude of horizontal curvature in unconstrained and constrained movements.

Human Movement Science, Jun 1, 2012

Although variations in the standard prehensile pattern can be found in the literature, these alte... more Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7 cm in diameter) were placed at 30, 60, 90, or 120 cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping.

Journal of Experimental Psychology: Human Perception and Performance, 1999

The nature of the interrelations among movement amplitude, movement time, and peak velocity was a... more The nature of the interrelations among movement amplitude, movement time, and peak velocity was addressed in 2 experiments in which participants reached for stationary and moving objects. Movement time was found to scale with the distance between the hand and the object at the onset of movement but to be relatively independent of object speed. Peak velocity, however, was found to scale with both these variables. The origin of these interrelations cannot be understood within the framework of existing trajectory formation models that are based on optimization procedures. A dynamical perspective in which the movements are considered in an object-attached coordinate frame allows for their emergence. This is demonstrated by simulation of a nonlinear model, built up from Rayleigh and Duffing components, with the nonlinear dissipative parameter being associated with amplitude scaling.

PLOS ONE, Jul 17, 2015

In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a ... more In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a recent study on ergometers demonstrated that antiphase crew coordination might be mechanically more efficient by reducing the power lost to within-cycle velocity fluctuations of the boat. However, coupled oscillator dynamics predict the stability of the coordination to decrease with increasing stroke rate, which in case of antiphase may eventually yield breakdowns to in-phase. Therefore, this study examined the effects of increasing stroke rate on in-and antiphase crew coordination in rowing dyads. Eleven experienced dyads rowed on two mechanically coupled ergometers on slides, which allowed the ergometer system to move back and forth as one 'boat'. The dyads performed a ramp trial in both inand antiphase pattern, in which stroke rates gradually increased from 30 strokes per minute (spm) to as fast as possible in steps of 2 spm. Kinematics of rowers, handles and ergometers were captured. Two dyads showed a breakdown of antiphase into in-phase coordination at the first stroke rate of the ramp trial. The other nine dyads reached between 34-42 spm in antiphase but achieved higher rates in in-phase. As expected, the coordinative accuracy in antiphase was worse than in in-phase crew coordination, while, somewhat surprisingly, the coordinative variability did not differ between the patterns. Whereas crew coordination did not substantially deteriorate with increasing stroke rate, stroke rate did affect the velocity fluctuations of the ergometers: fluctuations were clearly larger in the inphase pattern than in the antiphase pattern, and this difference significantly increased with stroke rate. Together, these results suggest that although antiphase rowing is less stable (i.e., less resistant to perturbation), potential on-water benefits of antiphase over in-phase rowing may actually increase with stroke rate.

Journal of Environmental Psychology, Mar 1, 2015

Environmental psychologists have used Gibson' concept of affordances to understand the playing be... more Environmental psychologists have used Gibson' concept of affordances to understand the playing behavior of children. This concept refers to the action possibilities the environment offers the animal. The present study examined whether children are attracted to challenging affordances in a simple playscape. Thirty children aged between 7 and 10 years old played freely in a playscape consisting of blocks that varied in height and were placed at different distances from each other. After the playing, several perceived and actual action boundaries of the children were measured. The further the child can jump, the wider the gaps jumped across. Yet, overall the children tended to actualize affordances that were not challenging for them. Moreover, especially in going down and in crossing gaps of certain widths, children preferred to jump even when stepping was possible. The implications of these findings are explored for both theories of playing and the design of playgrounds.

In sports, psychological momentum (PM) develops when athletes perceive they are moving toward or ... more In sports, psychological momentum (PM) develops when athletes perceive they are moving toward or away from a desired outcome, such as the victory (Den Hartigh, Gernigon, Van Yperen, Marin & Van Geert, 2014). According to recent research, this perception elicits positive and negative changes in athletes’ psychological states (e.g., confidence, optimism), as well as their momentary abilities (e.g., Den Hartigh et al., 2014; Den Hartigh, Van Geert, Van Yperen, Cox, & Gernigon, 2016; IsoAhola & Dotson, 2014, 2016). Interestingly, abilities are a key ingredient of the concept of affordances, which are the action possibilities for organisms in their environment (Gibson, 1979). In this experimental study, we aimed to provide a first test of a possible link between PM and affordances. We examined whether athletes’ judgments of affordances vary with PM. We designed a golf course on which participants, after a training, were asked to place the ball at their maximum “puttable” distance from the hole. Next, participants played a golf putting match against an opponent, in which the first to take a lead of 5 points would win the match. They wore visual occlusion goggles to prevent them from seeing the actual result, and we manipulated the scoring pattern to induce positive (from -4 to +4 points) or negative PM (from +4 to -4 points). We then asked the participants again to indicate their maximum puttable distance from the hole. Results provided first evidence for a PM-affordances link: Relative to the baseline distance (100%), the judgment of the puttable distance corresponded to 113% during positive PM (95% CI = 97% to 130%) and to 83% (95% CI = 69% to 95%) during negative PM. Together, these results suggest that athletes’ affordances change when they experience positive or negative PM. This sheds a new light on the dynamics of perception-action processes and PM in sports.

In sports matches, psychological momentum (PM) develops when moving toward or away from a desired... more In sports matches, psychological momentum (PM) develops when moving toward or away from a desired outcome, such as the victory. This elicits various psychological and behavioral changes within the athlete. In empirical studies, our research team found positive and negative changes in, amongst others, confidence and effort exertion while athletes moved toward or away from a victory (e.g., Den Hartigh et al., 2014, 2016; Den Hartigh & Gernigon, 2018). Recently, we proceeded by studying whether PM influences athletes’ perception of the environment and the possibilities for action it offers (affordances, see Fajen et al., 2008). We asked participants to make practice putts on a golf course. Subsequently, they were asked to place the ball at their maximum ‘puttable’ distance and to judge the hole size. Next, participants played a match against an opponent, in which the first to take a lead of 5 points would win (they won a point when making the putt or being closest to the hole). The experimenter manipulated the scoring pattern: Participants either came back from a four-point lag to a four-point lead (positive PM), or underwent the opposite scenario (negative PM). Then, participants judged their maximum puttable distance and the hole size again. Results provided first evidence for a PM-affordances link: Relative to the baseline, the judgment of the puttable distance corresponded to 113% during positive PM (95% CI = 97% to 130%) and to 87% (95% CI = 69% to 95%) during negative PM. No significant effects were found for hole-size judgments.

Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Human Movement Science, Aug 1, 2010

Both in the catching and grasping component of prehension, the hand opens and closes before hand-... more Both in the catching and grasping component of prehension, the hand opens and closes before hand-object contact is made. The initiation of hand closure has to be coordinated with the time course of the decrease of the distance between the hand and the target object, i.e., with the reaching component in prehension or the approach of the target in catching. The authors investigated if this initiation of hand closure could be explained by a common control. For this purpose, they fitted the dynamic timing model to data from the two tasks. In both tasks, participants were asked to get hold of an object approaching along the table top at a constant velocity. In the prehension task, participants could reach out to grasp the object; in the catching task, they were required to keep their hand stationary. In comparison with other accounts, the dynamic timing model performed best in explaining the data. The model proved adequate for the prehension task but not for the current catching task.

HAL (Le Centre pour la Communication Scientifique Directe), 2017

Ecological Psychology, Jun 23, 2022

Human Movement Science, Jun 1, 2012

Neuroscience Letters, 2010

Point-to-point movements constrained to the horizontal plane are generally straight, although the... more Point-to-point movements constrained to the horizontal plane are generally straight, although they exhibit slight deviations from straightness. Unconstrained horizontal movements (i.e., movements where the hand is lifted) are more curved in their projection onto the horizontal plane than constrained movements. It has been argued that this difference in horizontal curvature is due to differences in the space in which the movements were planned (joint space versus work space, respectively). The current study challenged this explanation. We found that horizontal curvature of constrained movements increased when moving over a round surface compared to moving over a flat surface and when friction was low compared to when friction was high. Because all these movements were constrained movements this suggests that the earlier reported differences in horizontal curvature between constrained and unconstrained movements may not originate from a difference in the movements' planning space. The discussion addresses how factors related to planning and factors related to biomechanics may contribute to the magnitude of horizontal curvature in unconstrained and constrained movements.

Human Movement Science, Jun 1, 2012

Although variations in the standard prehensile pattern can be found in the literature, these alte... more Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7 cm in diameter) were placed at 30, 60, 90, or 120 cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping.

Journal of Experimental Psychology: Human Perception and Performance, 1999

The nature of the interrelations among movement amplitude, movement time, and peak velocity was a... more The nature of the interrelations among movement amplitude, movement time, and peak velocity was addressed in 2 experiments in which participants reached for stationary and moving objects. Movement time was found to scale with the distance between the hand and the object at the onset of movement but to be relatively independent of object speed. Peak velocity, however, was found to scale with both these variables. The origin of these interrelations cannot be understood within the framework of existing trajectory formation models that are based on optimization procedures. A dynamical perspective in which the movements are considered in an object-attached coordinate frame allows for their emergence. This is demonstrated by simulation of a nonlinear model, built up from Rayleigh and Duffing components, with the nonlinear dissipative parameter being associated with amplitude scaling.

PLOS ONE, Jul 17, 2015

In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a ... more In rowing, perfect synchronisation is important for optimal performance of a crew. Remarkably, a recent study on ergometers demonstrated that antiphase crew coordination might be mechanically more efficient by reducing the power lost to within-cycle velocity fluctuations of the boat. However, coupled oscillator dynamics predict the stability of the coordination to decrease with increasing stroke rate, which in case of antiphase may eventually yield breakdowns to in-phase. Therefore, this study examined the effects of increasing stroke rate on in-and antiphase crew coordination in rowing dyads. Eleven experienced dyads rowed on two mechanically coupled ergometers on slides, which allowed the ergometer system to move back and forth as one 'boat'. The dyads performed a ramp trial in both inand antiphase pattern, in which stroke rates gradually increased from 30 strokes per minute (spm) to as fast as possible in steps of 2 spm. Kinematics of rowers, handles and ergometers were captured. Two dyads showed a breakdown of antiphase into in-phase coordination at the first stroke rate of the ramp trial. The other nine dyads reached between 34-42 spm in antiphase but achieved higher rates in in-phase. As expected, the coordinative accuracy in antiphase was worse than in in-phase crew coordination, while, somewhat surprisingly, the coordinative variability did not differ between the patterns. Whereas crew coordination did not substantially deteriorate with increasing stroke rate, stroke rate did affect the velocity fluctuations of the ergometers: fluctuations were clearly larger in the inphase pattern than in the antiphase pattern, and this difference significantly increased with stroke rate. Together, these results suggest that although antiphase rowing is less stable (i.e., less resistant to perturbation), potential on-water benefits of antiphase over in-phase rowing may actually increase with stroke rate.

Journal of Environmental Psychology, Mar 1, 2015

Environmental psychologists have used Gibson' concept of affordances to understand the playing be... more Environmental psychologists have used Gibson' concept of affordances to understand the playing behavior of children. This concept refers to the action possibilities the environment offers the animal. The present study examined whether children are attracted to challenging affordances in a simple playscape. Thirty children aged between 7 and 10 years old played freely in a playscape consisting of blocks that varied in height and were placed at different distances from each other. After the playing, several perceived and actual action boundaries of the children were measured. The further the child can jump, the wider the gaps jumped across. Yet, overall the children tended to actualize affordances that were not challenging for them. Moreover, especially in going down and in crossing gaps of certain widths, children preferred to jump even when stepping was possible. The implications of these findings are explored for both theories of playing and the design of playgrounds.

In sports, psychological momentum (PM) develops when athletes perceive they are moving toward or ... more In sports, psychological momentum (PM) develops when athletes perceive they are moving toward or away from a desired outcome, such as the victory (Den Hartigh, Gernigon, Van Yperen, Marin & Van Geert, 2014). According to recent research, this perception elicits positive and negative changes in athletes’ psychological states (e.g., confidence, optimism), as well as their momentary abilities (e.g., Den Hartigh et al., 2014; Den Hartigh, Van Geert, Van Yperen, Cox, & Gernigon, 2016; IsoAhola & Dotson, 2014, 2016). Interestingly, abilities are a key ingredient of the concept of affordances, which are the action possibilities for organisms in their environment (Gibson, 1979). In this experimental study, we aimed to provide a first test of a possible link between PM and affordances. We examined whether athletes’ judgments of affordances vary with PM. We designed a golf course on which participants, after a training, were asked to place the ball at their maximum “puttable” distance from the hole. Next, participants played a golf putting match against an opponent, in which the first to take a lead of 5 points would win the match. They wore visual occlusion goggles to prevent them from seeing the actual result, and we manipulated the scoring pattern to induce positive (from -4 to +4 points) or negative PM (from +4 to -4 points). We then asked the participants again to indicate their maximum puttable distance from the hole. Results provided first evidence for a PM-affordances link: Relative to the baseline distance (100%), the judgment of the puttable distance corresponded to 113% during positive PM (95% CI = 97% to 130%) and to 83% (95% CI = 69% to 95%) during negative PM. Together, these results suggest that athletes’ affordances change when they experience positive or negative PM. This sheds a new light on the dynamics of perception-action processes and PM in sports.

In sports matches, psychological momentum (PM) develops when moving toward or away from a desired... more In sports matches, psychological momentum (PM) develops when moving toward or away from a desired outcome, such as the victory. This elicits various psychological and behavioral changes within the athlete. In empirical studies, our research team found positive and negative changes in, amongst others, confidence and effort exertion while athletes moved toward or away from a victory (e.g., Den Hartigh et al., 2014, 2016; Den Hartigh & Gernigon, 2018). Recently, we proceeded by studying whether PM influences athletes’ perception of the environment and the possibilities for action it offers (affordances, see Fajen et al., 2008). We asked participants to make practice putts on a golf course. Subsequently, they were asked to place the ball at their maximum ‘puttable’ distance and to judge the hole size. Next, participants played a match against an opponent, in which the first to take a lead of 5 points would win (they won a point when making the putt or being closest to the hole). The experimenter manipulated the scoring pattern: Participants either came back from a four-point lag to a four-point lead (positive PM), or underwent the opposite scenario (negative PM). Then, participants judged their maximum puttable distance and the hole size again. Results provided first evidence for a PM-affordances link: Relative to the baseline, the judgment of the puttable distance corresponded to 113% during positive PM (95% CI = 97% to 130%) and to 87% (95% CI = 69% to 95%) during negative PM. No significant effects were found for hole-size judgments.