Exposure to delayed sensory feedback changes perceived simultaneity between action and feedback [temporal recalibration ] and even modulates the sense of agency over the feedback. To date, however, it is not clear whether the modulation of SoA by TR is caused by a change in perceptual sensitivity or decision criterion of self-agency. This experimental research aimed to tease apart these two by applying the signal detection theory to the agency judgment over auditory feedback after voluntary action. Participants heard a short (...) sequence of tone pips with equal inter-onset intervals, and they reproduced it by pressing a computer mouse. The delay of each tone pip after the mouse press was manipulated as 80 or 180 ms. Subsequently, the participants reproduced it, in which the delay was fixed at 80 ms and there was a 50% chance that the computer took over the control of the tone pips from the participants. The participants’ task was to discriminate who controlled the tone pips and to judge synchrony between tone pips and mouse presses. Results showed that the modulation of the SoA by the TR is caused by a shift in the decision criterion but not in the perceptual sensitivity of agency. (shrink)

The psychopathological phenomenon of delusions of influence comprises variable disturbances of the self-environment-border leading to the feeling of external influence on thoughts, feelings, impulses or behaviors. Delusions of influence are a hallmark in psychotic illness, but nevertheless, attenuated forms can also appear in healthy individuals. Here we present a newly developed paradigm to induce and assess feelings of external influence during instructed imaginations in healthy individuals. In the current study, we asked 60 healthy individuals to visually imagine different objects. To (...) induce feelings of external influence, we applied one of three different physical setups, and informed the participants whether or not an external influence was attempted during the respective trial. The physical setup as well as the information given to the participants alone were able to modulate the feeling of external influence in all three interventions. The impact of information significantly exceeded the impact of the physical setup on the ratings of experienced external influence. Moreover, the response latency correlated with the estimated feeling of external influence. Additional analyses addressed the influence of the emotional content of imagined objects and examined the intensity and emotional valence of the imaginations. Further supplemental analyses correlated external influence estimation of the participants with other psychopathological measures. In conclusion, this study endorses a quantitative model of psychopathological characteristics, in this case feelings of external influence that can be induced by external cues. (shrink)

Color-motion asynchrony (CMA) refers to an apparent lag of direction of motion when a dynamic stimulus changes both color and direction at the same time. The subjective order of simultaneous events, however, is not only perceptual but also subject to illusions during voluntary actions. Self-initiated actions, for example, seem to precede their sensory outcomes following an adaptation to a delay between the action and the sensory feedback. Here, we demonstrate that the extent of the apparent asynchrony can be substantially reduced (...) when direction change is induced by a voluntary key press following a delay adaptation regime. We also show that the reduced color-motion asynchrony effect size following a motor-sensory recalibration is not a result of a change in the onset of perceived direction change relative to that of the color. This is particularly important as it implies, for the first time in the literature, that voluntary action is not only important in forming action-sensory outcome associations but may also act as a binding factor between the two perceptual features of a sensory event. (shrink)