Cristina Massen

Parallel programming of exogenous and endogenous components in the antisaccade task

In the antisaccade task subjects are required to suppress the reflexive tendency to look at a peripherally presented stimulus and to perform a saccade in the opposite direction instead. The present studies aimed at investigating the inhibitory mechanisms responsible for successful performance in this task, testing a hypothesis of parallel programming of exogenous and endogenous components: A reflexive saccade to the stimulus is automatically programmed and competes with the concurrently established voluntary programme to look in the opposite direction. The experiments followed the logic of selectively manipulating the speed of processing of these components and testing the prediction that a selective slowing of the exogenous component should result in a reduced error rate in this task, while a selective slowing of the endogenous component should have the opposite effect. The results provide evidence for the hypothesis of parallel programming and are discussed in the context of alternative accounts of antisaccade performance.

Programming tool-use actions.

When humans plan to execute a tool-use action, they can only specify the bodily movement parameters by taking into account the external target or goal of the tool-use action and the target-movement mapping implemented by the tool. In this study, the authors used the movement precuing method to investigate how people prepare for actions made with tools. More specifically, they asked whether people would be able to specify the spatial target and the target-movement mapping of the tool-use action independently of each other, and to what degree they would be able to prepare these components in advance. In 3 experiments, they precued either the target or the target-movement mapping of tool-use actions involving either a compatible or an incompatible target-movement mapping. Results indicate that participants benefit from partial advance information about the target-movement mapping, whereas no significant effects were found for precuing the spatial target of the action. These results occurred regardless of whether the target-movement mapping was compatible or incompatible and provide evidence for the notion that the target-movement mapping of a tool-use action is part of its cognitive representation.

Activation of action rules in action observation

Visually perceiving an action may activate corresponding motor programs. This automatic motor activation can occur both for higher level (i.e., the goal of an action) and for lower level (i.e., the specific effector with which it is executed) aspects of an action. The authors used a tool-use action paradigm to experimentally dissociate priming effects for observing the target, the movement, or the target-to-movement mapping of a tool-use action. In 3 experiments, participants took turns in acting, observing the tool-use action of another person in trial n-1, and executing an action in trial n. Trial transitions from n-1 to n were manipulated in 4 conditions with (a) mapping repeated and movement and target changed, (b) target repeated and movement and mapping changed, (c) movement repeated and target and mapping changed, or (d) all components repeated. Results indicate priming effects for repeating the target-to-movement mapping (i.e., the action rule) of a tool-use action and suggest that a rather abstract action schema is activated during action observation.

Embodied rules in tool use: A tool-switching study.

In tool use, a transformation rule defines the relation between an operating movement and its distal effect. This rule is determined by the tool structure and requires no explicit definition. The present study investigates how humans represent and apply compatible and incompatible transformation rules in tool use. In Experiment 1, participants had to switch between tools for which the respective transformation rules were either the same or different. This way, rule repetitions could be dissociated from tool repetitions. In Experiment 2, the application of transformation rules in tool use was compared with the application of explicitly defined rules. In Experiment 3, actions of tool use were cued either by tool pictures or by written tool names. The results suggest that a transformation rule in tool use has a cognitive representation that is independent of the concrete tool incorporating it. Furthermore, its application differs from the application of an explicitly defined rule in terms of reduced top-down processing.

The effect of continuous, nonlinearly transformed visual feedback on rapid aiming movements.

We investigated the ability to adjust to nonlinear transformations that allow people to control external systems like machines and tools. Earlier research (Verwey and Heuer 2007) showed that in the presence of just terminal feedback participants develop an internal model of such transformations that operates at a relatively early processing level (before or at amplitude specification). In this study, we investigated the level of operation of the internal model after practicing with continuous visual feedback. Participants executed rapid aiming movements, for which a nonlinear relationship existed between the target amplitude seen on the computer screen and the required movement amplitude of the hand on a digitizing tablet. Participants adjusted to the external transformation by developing an internal model. Despite continuous feedback, explicit awareness of the transformation did not develop and the internal model still operated at the same early processing level as with terminal feedback. Thus with rapid aiming movements, the type of feedback may not matter for the locus of operation of the internal model.

Action-sentence compatibility: the role of action effects and timing

Research on embodied approaches to language comprehension suggests that we understand linguistic descriptions of actions by mentally simulating these actions. Evidence is provided by the action-sentence compatibility effect (ACE) which shows that sensibility judgments for sentences are faster when the direction of the described action matches the response direction. In two experiments, we investigated whether the ACE relies on actions or on intended action effects. Participants gave sensibility judgments of auditorily presented sentences by producing an action effect on a screen at a location near the body or far from the body. These action effects were achieved by pressing a response button that was located in either the same spatial direction as the action effect, or in the opposite direction. We used a go/no-go task in which the direction of the to-be-produced action effect was either cued at the onset of each sentence (Experiment 1) or at different points in time before and after sentence onset (Experiment 2). Overall, results showed a relationship between the direction of the described action and the direction of the action effect. Furthermore, Experiment 2 indicated that depending on the timing between cue presentation and sentence onset, participants responded either faster when the direction of the described action matched the direction of the action effect (positive ACE), or slower (negative ACE). These results provide evidence that the comprehension of action sentences involves the activation of representations of action effects. Concurrently activated representations in sentence comprehension and action planning can lead to both priming and interference, which is discussed in the context of the theory of event coding.

Bimanual interference with compatible and incompatible tool transformations

The present study investigates bimanual interference in a tool-use task, in which two target locations had to be touched concurrently with two tools, one for each hand. Target locations were either in the same, or in different directions for the two hands. Furthermore, the tools implemented either a compatible or an incompatible relationship between the direction of target locations and the direction of associated bodily movements. Results indicated bimanual interference when the tools had to be moved to targets in different directions. Furthermore, this interference was much more pronounced when the tools required body movements that were spatially incompatible to the cued target locations as compared to when they were compatible. These results show that incompatible relationships between target directions and bodily movement directions can aggravate bimanual interference in tool use.

The role of proactive interference in mnemonic techniques

The success of many mnemonic techniques, such as the method of loci, is based on the use of specific well-known anchors, which are mentally combined with to-be-learned items and subsequently facilitate their retrieval. In our studies we intended to answer the question of whether the repeated application of the method of loci may result in proactive interference effects, as might be expected due to the applied association of items with the same loci each time the method is used. To this end, we manipulated list similarity in a typical proactive interference design and compared the method of loci with the link method and the rehearsal method, which do not involve the use of a specified set of anchors. Our results replicate those from other studies, which have shown that the use of a mnemonic technique leads to superior recall of list items compared to a simple rehearsal strategy. We were further able to show that the repeated learning of items from different categories results in moderate practice effects over three list-learning trials, whereas this effect is superimposed by an effect of proactive interference if different lists are composed of items from the same category. However, this effect of proactive interference was not increased for the method of loci, and we discuss this finding with regard to its practical implications.

Tool characteristics in imagery of tool actions.

Are tool characteristics represented in imagined tool actions? In two experiments participants imagined and executed coloring rectangles with a thick and a thin pen. In Experiment 2, an additional execution condition without visual feedback of coloring allowed us to dissociate between the relevance of kinesthetic and visual feedback. Pen thickness influenced coloring durations in all conditions, indicating that characteristics of a simple tool are represented during imagery. Imagination was shorter than execution, indicating that imagination may be less detailed than execution. Execution without visual feedback was even shorter than imagination, indicating that vision is more important than kinesthesis for differences between imagination and execution, and that either imagining the movement, inhibiting movement execution or imagining the progress of the action is effortful during imagery. In conclusion, characteristics of simple tools are represented in imagined tool actions but the representation of tools’ effects may not always be adequate.

Modality-specific organization in the representation of sensorimotor sequences.

Sensorimotor representations of movement sequences are hierarchically organized. Here we test the effects of different stimulus modalities on such organizations. In the visual group, participants responded to a repeated sequence of visually presented stimuli by depressing spatially compatible keys on a response pad. In the auditory group, learners were required to respond to auditorily presented stimuli, which had no direct spatial correspondence with the response keys: the lowest pitch corresponded to the leftmost key and the highest pitch to the rightmost key. We demonstrate that hierarchically and auto-organized sensorimotor representations are developed through practice, which are specific both to individuals and stimulus modalities. These findings highlight the dynamic and sensory-specific modulation of chunk processing during sensorimotor learning – sensorimotor chunking – and provide evidence that modality-specific mechanisms underlie the hierarchical organization of sequence representations.