Search

Details on the pilot study, the validation study and the main experiment

In contrast to classical theories of cognitive control, recent evidence suggests that cognitive control and unconscious automatic processing influence each other. First, masked semantic priming, an index of unconscious automatic processing, depends on attention to semantics induced by a previously executed task. Second, cognitive control operations (e.g., implementation of task sets indicating how to process a particular stimulus) can be activated by masked task cues, presented outside awareness. In this study, we combined both lines of research. We investigated in three experiments whether induction tasks and presentation of visible or masked task cues, which signal subsequent semantic or perceptual tasks but do not require induction task execution, comparably modulate masked semantic priming. In line with previous research, priming was consistently larger following execution of a semantic rather than a perceptual induction task. However, we observed in experiment 1 (masked letter cues) a reversed priming pattern following task cues (larger priming following cues signaling perceptual tasks) compared to induction tasks. Experiment 2 (visible letter cues) and experiment 3 (visible color cues) showed that this reversed priming pattern depended only on apriori associations between task cues and task elements (task set dominance), but neither on awareness nor on the verbal or non-verbal format of the cues. These results indicate that task cues have the power to modulate subsequent masked semantic priming through attentional mechanisms. Task-set dominance conceivably affects the time course of task set activation and inhibition in response to task cues and thus the direction of their modulatory effects on priming.

Objects which a human agent controls by efferent activities (such as real or virtual tools) can be perceived by the agent as belonging to his or her body. This suggests that what an agent counts as “body” is plastic, depending on what she or he controls. Yet there are possible limitations for such momentary plasticity. One of these limitations is that sensations stemming from the body (e.g., proprioception) and sensations stemming from objects outside the body (e.g., vision) are not integrated if they do not sufficiently “match”. What “matches” and what does not is conceivably determined by long–term experience with the perceptual changes that body movements typically produce. Children have accumulated less sensorimotor experience than adults have. Consequently, they express higher flexibility to integrate body-internal and body-external signals, independent of their “match” as suggested by rubber hand illusion studies. However, children’s motor performance in tool use is more affected by mismatching body-internal and body-external action effects than that of adults, possibly because of less developed means to overcome such mismatches. We review research on perception-action interactions, multisensory integration, and developmental psychology to build bridges between these research fields. By doing so, we account for the flexibility of the sense of body ownership for actively controlled events and its development through ontogeny. This gives us the opportunity to validate the suggested mechanisms for generating ownership by investigating their effects in still developing and incomplete stages in children. We suggest testable predictions for future studies investigating both body ownership and motor skills throughout the lifespan.

Movements of a tool typically diverge from the movements of the hand manipulating that tool, such as when operating a pivotal lever where tool and hand move in opposite directions. Previous studies suggest that humans are often unaware of the position or movements of their effective body part (mostly the hand) in such situations. It has been suggested that this might be due to a "haptic neglect" of bodily sensations to decrease the interference of representations of body and tool movements. However, in principle this interference could also be decreased by neglecting sensations regarding the tool and focusing instead on body movements. While in most tool use situations the tool-related action effects are task-relevant and thus suppression of body-related rather than tool-related sensations is more beneficial for successful goal achievement, we manipulated this task-relevance in a controlled experiment. The results showed that visual, tool-related effect representations can be suppressed just as proprioceptive, body-related ones in situations where effect representations interfere, given that task-relevance of body-related effects is increased relative to tool-related ones.

Journal of vision 19(3), 1-24 (2019). doi:10.1167/19.3.14, Published by ARVO, Rockville, Md.

Data of naturalistic driving studies have shown that conventional Collision Avoidance Systems (CAS) activate a high rate of unnecessary alarms. These alarms are associated with situations predefined as hazardous by the system algorithm, while not perceived as hazardous by the human user. This driving simulator study aimed to identify factors that cause discrepancies between human hazard perception and the risk assessment of CAS. All participants encountered situations with a braking lead vehicle that would have usually activated alarms in conventional CAS. However, drivers’ hazard perception and the intensity of their braking responses varied dependent on the outcome of the conflict that either remained or dissolved. Additionally, the predictability of the outcome influenced drivers’ hazard perception, while it had no impact on their driving behaviour.