Biomedical subjects

Günther Knoblich

Publications and source records attributed to Günther Knoblich.

17 recordsLinked to original sources

PubMed2005

Continuous attraction toward phonological competitors.

Certain models of spoken-language processing, like those for many other perceptual and cognitive processes, posit continuous uptake of sensory input and dynamic competition between simultaneously active representations. Here, we provide compelling evidence for this continuity assumption by using a continuous response, hand movements, to track the temporal dynamics of lexical activations during real-time spoken-word recognition in a visual context. By recording the streaming x, y coordinates of continuous goal-directed hand movement in a spoken-language task, online accrual of acoustic-phonetic input and competition between partially active lexical representations are revealed in the shape of the movement trajectories. This hand-movement paradigm allows one to project the internal processing of spoken-word recognition onto a two-dimensional layout of continuous motor output, providing a concrete visualization of the attractor dynamics involved in language processing.

Adult↗

PubMed2005

Compensation for and adaptation to changes in the environment.

Human motor behavior is remarkably accurate, even though many everyday skills require flexible adjustments between motor activity and its consequences in extracorporeal space. The present study addressed two questions: first, how do people compensate for unpredictable changes in the environment, and second, how do they adapt to such changes? In Experiment 1, participants repeatedly and continuously drew up and down strokes on a writing pad. After drawing under a base mapping, either (a) a change of target position, or (b) a change of gain, or (c) both occurred. Compensation for gain changes occurred later than compensation for changes in target position. In addition, there were aftereffects of the previous movement in accuracy and movement time. Adaptation to changes occurred in reference to extracorporeal space, with motor constraints as a limiting factor. In Experiment 2 we obtained similar effects when participants had more time to adapt. The view that movements are planned in reference to their goals in extracorporeal space is supported.

Adaptation, Physiological↗

PubMed2005

Agency in the face of error.

Experiencing oneself as the cause of an action is a fundamental building block for a sense of self. A recent study by Sato and Yasuda provides evidence that motor prediction contributes to the experience of agency. Their findings demonstrate that agency is experienced not only for intended, but also for erroneous, unintended actions. This extends our knowledge on the phenomenology of action, and raises questions about the relation between explicit reports and agency-related changes in sensation and perception.

Awareness↗

PubMed2005

The case for motor involvement in perceiving conspecifics.

Perceiving other people's behaviors activates imitative motor plans in the perceiver, but there is disagreement as to the function of this activation. In contrast to other recent proposals (e.g., that it subserves overt imitation, identification and understanding of actions, or working memory), here it is argued that imitative motor activation feeds back into the perceptual processing of conspecifics' behaviors, generating top-down expectations and predictions of the unfolding action. Furthermore, this account incorporates recent ideas about emulators in the brain-mental simulations that run in parallel to the external events they simulate-to provide a mechanism by which motoric involvement could contribute to perception. Evidence from a variety of literatures is brought to bear to support this account of perceiving human body movement.

Brain↗

PubMed2005

Action comprehension: deriving spatial and functional relations.

A perceived action can be understood only when information about the action carried out and the objects used are taken into account. It was investigated how spatial and functional information contributes to establishing these relations. Participants observed static frames showing a hand wielding an instrument and a potential target object of the action. The 2 elements could either match or mismatch, spatially or functionally. Participants were required to judge only 1 of the 2 relations while ignoring the other. Both irrelevant spatial and functional mismatches affected judgments of the relevant relation. Moreover, the functional relation provided a context for the judgment of the spatial relation but not vice versa. The results are discussed in respect to recent accounts of action understanding.

Adult↗

PubMed2004

Recognizing one's own clapping: the role of temporal cues.

Do individuals recognize their own clapping? We investigated this question with an off-line paradigm in which the perception of the claps is temporally separated from their generation. In a first experiment, we demonstrated that acoustic recordings of clapping provide sufficient information for discriminating between one's own performance and that of another participant. Self-recognition was still preserved when the claps were reproduced by uniform tones that only retained their temporal pattern. In a subsequent experiment, we verified that the general tempo provides an important cue for self-recognition. Finally, we showed that self-recognition does not rely on concurrent synchronization of actual movements with the auditory sequences. The results are discussed in the light of current theories about perception-action links.

Adolescent↗

PubMed2004

Self-monitoring in patients with schizophrenia.

BACKGROUND: The present study investigated whether a failure of self-monitoring contributes to core syndromes of schizophrenia. METHOD: Three groups of patients with a DSM-IV diagnosis of schizophrenia (n = 27), with either prominent paranoid hallucinatory or disorganization syndrome, or without these symptoms, and a matched healthy control group (n = 23) drew circles on a writing pad connected to a PC monitor. Subjects were instructed to continuously monitor the relationship between their hand movements and their visual consequences. They were asked to detect gain changes in the mapping. Self-monitoring ability and the ability to automatically correct movements were assessed. RESULTS: Patients with either paranoid-hallucinatory syndrome or formal thought disorder were selectively impaired in their ability to detect a mismatch between a self-generated movement and its consequences, but not impaired in their ability to automatically compensate for the gain change. CONCLUSIONS: These results support the claim that a failure of self-monitoring may underlie the core symptoms of schizophrenia.

Adult↗

PubMed2004

Deceiving oneself about being in control: conscious detection of changes in visuomotor coupling.

Previous research has demonstrated that compensatory movements for changes in visuomotor coupling often are not consciously detected. But what factors affect the conscious detection of such changes? This issue was addressed in 4 experiments. Participants carried out a drawing task in which the relative velocity between the actual movement and its visual consequences was perturbed. Unconscious compensatory movements and conscious detection rates were simultaneously recorded. There was an invariant relationship between the extent of the change and its conscious detection that was proportional to the initial drawing velocity. This suggests that conscious change detection relies on a system that integrates visual and motor information-as, for instance, suggested by the internal model theory of motor control. Figural discrepancies increased the detection rates, indicating that additional cues for the what system facilitate conscious change detection.

Adult↗

PubMed2004

Perceiving action identity: how pianists recognize their own performances.

Can skilled performers, such as artists or athletes, recognize the products of their own actions? We recorded 12 pianists playing 12 mostly unfamiliar musical excerpts, half of them on a silent keyboard. Several months later, we played these performances back and asked the pianists to use a 5-point scale to rate whether they thought they were the person playing each excerpt (1 = no, 5 = yes). They gave their own performances significantly higher ratings than any other pianist's performances. In two later follow-up tests, we presented edited performances from which differences in tempo, overall dynamic (i.e., intensity) level, and dynamic nuances had been removed. The pianists' ratings did not change significantly, which suggests that the remaining information (expressive timing and articulation) was sufficient for self-recognition. Absence of sound during recording had no significant effect. These results are best explained by the hypothesis that an observer's action system is most strongly activated during perception of self-produced actions.

Adult↗

PubMed2004

Spatial perception and control.

We investigated whether the perceived vanishing point of a moving stimulus becomes more accurate as one's degree of control over the stimulus increases. Either alone or as a member of a pair, participants controlled the progression of a dot stimulus back and forth across a computer monitor. They did so via right and left buttonpresses that incremented the dot's velocity rightward and leftward, respectively. The participants in the individual condition had control of both buttons. Those in the group condition had control of only one. As the participants slowed the dot to change its direction of travel, it unexpectedly disappeared. Localizations of the vanishing point became more accurate as the participants' control over the dot increased. The data bridge a gap between accounts of localization error that rely solely on stimulus and cognitive factors, and accounts derived from research on action and spatial perception, which tend to rely on action-planning factors.

Adolescent↗

PubMed2003

The neural correlates of perceiving one's own movements.

Feedforward mechanisms are important for movement control. They may also contribute to the identification of self-produced actions by attenuating the sensory consequences of self-produced movements. In our study, subjects opened and closed their hand slowly and continuously (0.5 Hz). This movement was filmed with an MRI compatible video camera and projected online onto a screen, viewed by the subject while BOLD contrast was measured with fMRI. The temporal delay between movement and feedback was parametrically varied (0-200 ms). In each trial, subjects judged whether there was a delay or not. There was a positive correlation between the extent of the temporal delay and activation in the right posterior superior temporal cortex (pSTS) and a negative correlation in the left putamen. A second analysis addressed the neural correlates of subjective judgement under conditions of uncertainty. This contrast showed a differential activation in the cerebellum. These results support the assumption of a forward model implying that predictions generated in motor areas attenuate sensory areas. They also suggest that efference copy mechanisms are not located within specific brain areas but are implemented as a specific form of interaction between perceptual and motor areas depending on the modalities and the type of actions involved. Further, conscious detection of small temporal deviations might be based on signals generated in the cerebellum which provide fine-grained temporal information. These results might be useful to refine theories about the role of forward mechanisms in the emergence of disorders of the self, such as in schizophrenia.

Adult↗

PubMed2003

Representing others' actions: just like one's own?

Previous research has shown that observing others' actions can affect individual performance of the same actions. In the present study, we developed a new paradigm to investigate whether and how complementary actions at the disposal of another agent are represented and influence one's own actions. A spatial compatibility task was distributed among two people so that each participant took care of one of two responses. The identical task was performed alone and alongside another participant. There was a spatial compatibility effect in the group setting only. It was similar to the effect obtained when one person took care of both responses. This result suggests that one's own actions and others' actions are represented in a functionally equivalent way.

Adolescent↗

PubMed2003

Off-line authorship effects in action perception.

Does the perception of our actions differ from the perception of other individuals' actions when we observe them, like other individual's actions, in an offline perspective? Previous studies, using recognition as well as prediction judgments, suggest that it does even if the stimulus information is reduced to a single moving point-light. Here, we assessed whether this difference also affects the timing of actions. This was tested in two experiments, using a specific synchronization task. After some practice, self-generated action events were anticipated faster than other action events, provided that the anticipation could not be accomplished sufficiently well on the basis of easily detectable cues. The results are discussed with regard to the previous findings of off-line authorship effects in action perception.

Adult↗

PubMed2003

Action identity: evidence from self-recognition, prediction, and coordination.

Prior research suggests that the action system is responsible for creating an immediate sense of self by determining whether certain sensations and perceptions are the result of one's own actions. In addition, it is assumed that declarative, episodic, or autobiographical memories create a temporally extended sense of self or some form of identity. In the present article, we review recent evidence suggesting that action (procedural) knowledge also forms part of a person's identity, an action identity, so to speak. Experiments that addressed self-recognition of past actions, prediction, and coordination provide ample evidence for this assumption. The phenomena observed in these experiments can be explained by the assumption that observing an action results in the activation of action representations, the more so, when the action observed corresponds to the way in which the observer would produce it.

Awareness↗

PubMed2003

Observing one's hand become anarchic: an fMRI study of action identification.

The self seems to be a unitary entity remaining stable across time. Nevertheless, current theorizing conceptualizes the self as a number of interacting sub-systems involving perception, intention and action (self-model). One important function of such a self-model is to distinguish between events occurring as a result of one's own actions and events occurring as the result of somebody else's actions. We conducted an fMRI experiment that compared brain activation after an abrupt mismatch between one's own movement and its visual consequences with an abrupt mismatch between one's own movement and somebody else's visually perceived hand movement. A right fronto-parietal network was selectively active during a sudden mismatch between one's own observed and performed hand action.

Awareness↗

PubMed2003

Action coordination in groups and individuals: learning anticipatory control.

When individuals act alone, they can internally coordinate the actions at hand. Such coordination is not feasible when individuals act together in a group. The present research examines to what extent groups encounter specific challenges when acting jointly and whether these challenges impede extending planning into the future. Individuals and groups carried out a tracking task that required learning a new anticipatory control strategy. The results show that groups face additional demands that are harder to overcome when planning needs to be extended into the future. Information about others' actions is a necessary condition for groups to effectively learn to extend their plans. Possible mechanisms for exerting and learning anticipatory control are discussed.

Adult↗

PubMed2002

Self-recognition: body and action.

How do I know it was me who moved? A recent experimental study illustrates the contribution of one's body schema and awareness of one's own actions to self-recognition. The results provide evidence that bodily cues and action cues are important in self-recognition, and they demonstrate that action cues overrule bodily cues.

Journal Article↗