Christine Sattler

Dynamics of feature binding during object-selective attention

Objects in the environment may be attended selectively and perceived as unified ensembles of their constituent features. To investigate the timing and cortical localization of feature-integration mechanisms in object-based attention, recordings of event-related potentials and magnetic fields were combined with functional MRI while subjects attended to one of two superimposed transparent surfaces formed by arrays of dots moving in opposite directions. A spatiotemporal analysis revealed evidence for a rapid increase in neural activity localized to a color-selective region of the fusiform gyrus when the surface moving in the attended direction displayed an irrelevant color feature. These data provide support for the “integrated-competition” model of object-selective attention and point to a dynamic neural substrate for the rapid binding process that links relevant and irrelevant features to form a unified perceptual object.

Binding of multidimensional context information as a distinctive characteristic of 'remember' judgments

This research investigated the cognitive processes underlying remember-know judgments in terms of contextual binding in multidimensional source memory. Stochastic dependence between the retrieval of different context attributes, which formed the empirical criterion of binding, was observed for remembered items but not for known items. Experiment 1 showed that the qualitative difference in the stochastic relation holds even if quantitative source-memory performance is equated for items with remember and know judgments. Experiment 2 generalized the findings to context information from different modalities, and Experiment 3 ruled out a spurious stochastic dependence due to interindividual differences. Supporting recent dual-process models of remember-know judgments, the findings show that remember and know judgments differ with respect to binding processes that correspond to episodic recollection.

Metacognitive inferences in source memory judgements: The role of perceived differences in item recognition

This research investigated the hypothesis that metacognitive inferences in source memory judgements are based on the recognition or nonrecognition of an event together with perceived or expected differences in the recognizability of events from different sources. The hypothesis was tested with a multinomial source-monitoring model that allowed separation of source-guessing tendencies for recognized and unrecognized items. Experiments 1A and 1B manipulated the number of item presentations as relevant source information and revealed differential guessing tendencies for recognized and unrecognized items, with a bias to attribute unrecognized items to the source associated with poor item recognition. Experiments 2A and 2B replicated the findings with a manipulation of presentation time and extended the analysis to subjective differences in item recognition. Experiments 3A and 3B used more natural source information by varying type of acoustic signal and demonstrated that subjective theories about differences in item recognition are sufficient to elicit differential source-guessing biases for recognized and unrecognized items. Together the findings provide new insights into the cognitive processes underlying source memory decisions, which involve episodic memory and reconstructive tendencies based on metacognitive beliefs and general world knowledge.

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.

Coordinative constraints in bimanual tool use

This study investigates coordinative constraints when participants execute discrete bimanual tool use actions. Participants moved two levers to targets that were either presented near the proximal parts of the levers or near the distal tips of the levers. In the first case, the tool transformation (i.e. the relationship between hand movement direction and target direction) was compatible, whereas in the second case, it was incompatible. We hypothesized that an egocentric constraint (i.e. a preference for moving the hands and tools in a mirror-symmetrical fashion) would be dominant when targets are presented near the proximal parts of the levers because in this situation, movements can be coded in terms of body-related coordinates. Furthermore, an allocentric constraint (i.e. a preference to move the hands in the same (parallel) direction in extrinsic space) was expected to be dominant when one of the targets or both are presented near the distal parts of the levers because in this condition, movements have to be coded in an external reference frame. The results show that when both targets are presented near the proximal parts of the levers, participants are faster and produce less errors with mirror-symmetrical when compared to parallel movements. Furthermore, the RT mirror-symmetry advantage is eliminated, when both targets are presented near the distal parts of the levers, and it is reversed, when the target for one lever is presented near its distal part and the target for the other lever is presented near its proximal part. These results show that the dominance of egocentric and allocentric coordinative constraints in bimanual tool use depends on whether movements are coded in terms of body-related coordinates or in an external reference frame.

What to do and how to do it: action representations in tool use

Research on bimanual coordination has shown that the efficiency of programming an action is determined by the way the action is cognitively represented. In tool use, actions can be represented with respect to the spatial goal of the action (e.g., the nail that is to be hit by a hammer) or with respect to the tool and its transformation (i.e., the function that maps external target locations onto corresponding bodily movements). We investigated whether the way of cuing bimanual actions with tools affects their cognitive representation and the efficiency with which they are programmed. In one group of participants, tool transformations were specified by symbolic cues, whereas the targets were indicated by direct spatial cues. In another group of participants, symbolic cues specified the targets of the tool-use actions, whereas tool transformations were indicated by direct spatial cues. In a third group, both targets and tool transformations were cued directly by spatial cues. It was hypothesized that different cognitive representations would result in more or less efficient programming of the action. Results indicated longer reaction times and a higher error rate in the group with symbolic cuing of the targets as compared to the group with symbolic cuing of the transformations. The latter did not differ much from the direct cuing group. These results suggest that it is more efficient to represent bimanual tool-use actions in terms of the tool transformations involved than in terms of the targets at which they are directed.

Bimanual interference associated with handling different tool transformations

Research on bimanual coordination of hand movements has identified several loci of bimanual interference, including interference because of programming different movement parameters or selecting different targets for the two hands. This study investigates the extent and origin of interference when participants execute bimanual actions with tools. In the experiments, participants moved two tools, one with each hand, to two directly cued target locations. One type of tool transformed the body movement into a spatially compatible movement of the effective part of the tool, whereas the other transformed it into a spatially incompatible movement. Tool transformations for the two hands were either the same or different. Furthermore, target locations were either in the same or in different spatial directions. Results indicated significantly shorter reaction times (RTs) and less errors when tool transformations were the same for both hands. In addition, movements were initiated more quickly and less error-prone when targets were in the same direction, but this effect was modulated by the congruency of the two lever transformations. Investigations of the time course of the effects revealed that they were not because of early perceptual processing (Experiment 2). Furthermore, the general pattern of results occurred for different grip positions (Experiment 3) and different lever types (Experiment 4), suggesting that it reflects rather general constraints in bimanual coordination of tool-use actions.