Christoph Teufel

Seeing other minds: attributed mental states influence perception

A current consensus views social perception as a bottom-up process in which the human brain uses social signals to make inferences about anothers mental state. Here we propose that, contrary to this model, even the most basic perceptual processing of a social stimulus and closely associated automatic responses are modulated by mental-state attribution. We suggest that social perception is subserved by an interactive bidirectional relationship between the neural mechanisms supporting basic sensory processing of social information and the theory-of-mind system. Consequently, processing of a social stimulus cannot be divorced from its representation in terms of mental states. This hypothesis has far-reaching implications for our understanding of both the healthy social brain and characteristic social failures in psychopathology.

Mental-State Attribution Drives Rapid, Reflexive Gaze Following

When presented with a face stimulus whose gaze is diverted, observers’ attention shifts to locations fixated by the face. Such “gaze following” has been characterized by some previous studies as a consequence of sophisticated theory of mind processes, but by others (particularly those employing the “gaze-cuing” paradigm) as an involuntary response that is triggered directly and reflexively by the physical features of a face. To address this apparent contradiction, we modified the gaze-cuing paradigm using a deception procedure to convince observers that prerecorded videos of an experimenter making head turns and wearing mirrored goggles were a “live” video link to an adjacent room. In two experiments, reflexive gaze following was found when observers believed that the model was wearing transparent goggles and could see, but it was significantly reduced when they believed that the experimenter wore opaque goggles and could not see. These results indicate that the attribution of the mental state “seeing” to a face plays a role in controlling even reflexive gaze following.

Shift toward prior knowledge confers a perceptual advantage in early psychosis and psychosis-prone healthy individuals

Significance Perceiving things that are not there and holding unfounded, bizarre beliefs (hallucinations and delusions, respectively) are psychotic symptoms that occur in particular syndromes including affective psychoses, paranoid states, and schizophrenia. We studied the emergence of this loss of contact with reality based on current models of normal brain function. Working with clinical individuals experiencing early psychosis and nonclinical individuals with high levels of psychosis proneness, we show that their visual perception is characterized by a shift that favors prior knowledge over incoming sensory evidence. Given that these alterations in information processing are evident early on in psychosis and even in association with subtle perceptual changes indicating psychosis proneness, they may be important factors contributing to the emergence of severe mental illnesses. Many neuropsychiatric illnesses are associated with psychosis, i.e., hallucinations (perceptions in the absence of causative stimuli) and delusions (irrational, often bizarre beliefs). Current models of brain function view perception as a combination of two distinct sources of information: bottom-up sensory input and top-down influences from prior knowledge. This framework may explain hallucinations and delusions. Here, we characterized the balance between visual bottom-up and top-down processing in people with early psychosis (study 1) and in psychosis-prone, healthy individuals (study 2) to elucidate the mechanisms that might contribute to the emergence of psychotic experiences. Through a specialized mental-health service, we identified unmedicated individuals who experience early psychotic symptoms but fall below the threshold for a categorical diagnosis. We observed that, in early psychosis, there was a shift in information processing favoring prior knowledge over incoming sensory evidence. In the complementary study, we capitalized on subtle variations in perception and belief in the general population that exhibit graded similarity with psychotic experiences (schizotypy). We observed that the degree of psychosis proneness in healthy individuals, and, specifically, the presence of subtle perceptual alterations, is also associated with stronger reliance on prior knowledge. Although, in the current experimental studies, this shift conferred a performance benefit, under most natural viewing situations, it may provoke anomalous perceptual experiences. Overall, we show that early psychosis and psychosis proneness both entail a basic shift in visual information processing, favoring prior knowledge over incoming sensory evidence. The studies provide complementary insights to a mechanism by which psychotic symptoms may emerge.

Deficits in sensory prediction are related to delusional ideation in healthy individuals

Research highlights ▶ Levels of sensory-motor predictions vary gradually in the healthy population. ▶ Deficient predictions are related to a delusion-like style of thinking. ▶ The continuum between health and psychosis exists even on a sensory-motor level.

Lack of orienting asymmetries in Barbary macaques : implications for studies of lateralized auditory processing

Shedding light on the origin of specific neuronal mechanisms for processing acoustic stimuli is important for understanding the evolution of primate communication. One of those specializations, lateralized processing of speech in humans, is a well-established finding. Evidence is accumulating that diverse animal taxa also show hemispheric asymmetries in the perception of conspecific sounds. Rhesus macaques, Macaca mulatta , for instance, show a right head-turning bias in response to playback of natural conspecific vocalizations, and a left head-turning bias in response to a heterospecific stimulus and several manipulated conspecific calls. This finding was related to a hemispheric specialization for processing conspecific versus heterospecific vocalizations. We conducted orienting experiments with Barbary macaques, M. sylvanus , living in the enclosure ‘La Foret des Singes’ in Rocamadour, France. In contrast to rhesus macaques, our subjects showed no orientation preferences in response to conspecific or heterospecific vocalizations. These results add to the puzzling mosaic picture of orienting asymmetries in different mammalian species and, in conjunction with other studies, highlight the importance of substantiating the assumption of a strong coupling of orienting bias and hemispheric asymmetry.

On the Relationship Between Lateralized Brain Function and Orienting Asymmetries

Hemispheric specializations for language perception constitute one of the classic topic in cognitive neuroscience. Evidence has accumulated to suggest that lateralized acoustic processing is not restricted to humans but is also found in numerous animal species. One of the methods used to track such lateralization is the orienting-asymmetry paradigm, a simple, noninvasive means to study lateralization that has been applied to a range of different species ranging from harpy eagles to humans. Here we summarize and compare the results of studies employing the orienting-asymmetry paradigm, showing that these studies yield largely inconsistent results. We critically discuss the methodologys implicit assumptions and conclude that the empirical inconsistencies produced by the orienting-asymmetry paradigm, and the lack of sufficient evidence supporting the paradigms underlying assumptions, warrant serious caution when interpreting results obtained by the method. Nontrivial interpretations of orienting-asymmetry results will require a much better understanding of how lateralized brain functions interact with overt behaviors.

How to (and how not to) think about top-down influences on visual perception.

The question of whether cognition can influence perception has a long history in neuroscience and philosophy. Here, we outline a novel approach to this issue, arguing that it should be viewed within the framework of top-down information-processing. This approach leads to a reversal of the standard explanatory order of the cognitive penetration debate: we suggest studying top-down processing at various levels without preconceptions of perception or cognition. Once a clear picture has emerged about which processes have influences on those at lower levels, we can re-address the extent to which they should be considered perceptual or cognitive. Using top-down processing within the visual system as a model for higher-level influences, we argue that the current evidence indicates clear constraints on top-down influences at all stages of information processing; it does, however, not support the notion of a boundary between specific types of information-processing as proposed by the cognitive impenetrability hypothesis.

Orienting asymmetries and lateralized processing of sounds in humans.

BackgroundLateralized processing of speech is a well studied phenomenon in humans. Both anatomical and neurophysiological studies support the view that nonhuman primates and other animal species also reveal hemispheric differences in areas involved in sound processing. In recent years, an increasing number of studies on a range of taxa have employed an orienting paradigm to investigate lateralized acoustic processing. In this paradigm, sounds are played directly from behind and the direction of turn is recorded. This assay rests on the assumption that a hemispheric asymmetry in processing is coupled to an orienting bias towards the contralateral side. To examine this largely untested assumption, speech stimuli as well as artificial sounds were presented to 224 right-handed human subjects shopping in supermarkets in Germany and in the UK. To verify the lateralized processing of the speech stimuli, we additionally assessed the brain activation in response to presentation of the different stimuli using functional magnetic resonance imaging (fMRI).ResultsIn the naturalistic behavioural experiments, there was no difference in orienting behaviour in relation to the stimulus material (speech, artificial sounds). Contrary to our predictions, subjects revealed a significant left bias, irrespective of the sound category. This left bias was slightly but not significantly stronger in German subjects. The fMRI experiments confirmed that the speech stimuli evoked a significant left lateralized activation in BA44 compared to the artificial sounds.ConclusionThese findings suggest that in adult humans, orienting biases are not necessarily coupled with lateralized processing of acoustic stimuli. Our results – as well as the inconsistent orienting biases found in different animal species – suggest that the orienting assay should be used with caution. Apparently, attention biases, experience, and experimental conditions may all affect head turning responses. Because of the complexity of the interaction of factors, the use of the orienting assay to determine lateralized processing of sound stimuli is discouraged.

Attribution of intentional causation influences the perception of observed movements: behavioral evidence and neural correlates.

Recent research on human agency suggests that intentional causation is associated with a subjective compression in the temporal interval between actions and their effects. That is, intentional movements and their causal effects are perceived as closer together in time than equivalent unintentional movements and their causal effects. This so-called intentional binding effect is consistently found for one’s own self-generated actions. It has also been suggested that intentional binding occurs when observing intentional movements of others. However, this evidence is undermined by limitations of the paradigm used. In the current study we aimed to overcome these limitations using a more rigorous design in combination with functional Magnetic Resonance Imaging (fMRI) to explore the neural underpinnings of intentional binding of observed movements. In particular, we aimed to identify brain areas sensitive to the interaction between intentionality and causality attributed to the observed action. Our behavioral results confirmed the occurrence of intentional binding for observed movements using this more rigorous paradigm. Our fMRI results highlighted a collection of brain regions whose activity was sensitive to the interaction between intentionality and causation. Intriguingly, these brain regions have previously been implicated in the sense of agency over one’s own movements. We discuss the implications of these results for intentional binding specifically, and the sense of agency more generally.

The promises and pitfalls of applying computational models to neurological and psychiatric disorders

Computational models are applied increasingly to the study of brain function and dysfunction. Teufel & Fletcher highlight the promise of this approach, but also some of the problems that can arise from the misapplication of such models. Using a simple analogy, they identify key principles necessary for avoiding common pitfalls.