Sylco S. Hoppenbrouwers

Affective touch modulates the rubber hand illusion

INTRODUCTIONnHumans experience touch as pleasant when this occurs with a certain velocity (1-10cm/s). Affective, pleasant touch is thought to be mediated by a distinct neural pathway consisting of un-myelinated tactile afferents (C tactile fibers) that respond to stroking with a low velocity on the hairy skin. As pleasant touch provides additional information on bodily signals we hypothesized that, compared to regular touch, pleasant touch would have a stronger effect on body ownership as measured through induction of the rubber hand illusion (RHI).nnnMETHODSnTwo experiments involving the RHI were conducted. In the first experiment, the effects of stroking velocity (3cm/s and 30cm/s) and stroking material (soft/rough) on the RHI were tested. In the second experiment, the effect of an additional stroking velocity (0.3cm/s) and side of stimulation (hairy and glabrous) was examined.nnnRESULTSnThe first experiment showed that low velocity stroking in combination with a soft material was not only regarded as most pleasant but also resulted in an enhanced RHI on proprioceptive drift and temperature measurements. In the second experiment, we confirmed that stroking with a velocity of 3cm/s resulted in a larger RHI in terms of proprioceptive drift. In addition, compared to regular touch, pleasant touch of the hairy skin resulted in a larger proprioceptive drift, while similar stroking on the glabrous side of the skin did not induce a stronger effect of RHI on proprioceptive drift.nnnCONCLUSIONnOur data suggest that pleasant touch modulates the body representation which is consistently reflected in a larger proprioceptive drift. Our data also suggest that C tactile fibers are likely to be involved in the modulation of body ownership.

Parsing fear: a reassessment of the evidence for fear deficits in psychopathy

Psychopathy is a personality disorder characterized by interpersonal manipulation and callousness, and reckless and impulsive antisocial behavior. It is often seen as a disorder in which profound emotional disturbances lead to antisocial behavior. A lack of fear in particular has been proposed as an etiologically salient factor. In this review, we employ a conceptual model in which fear is parsed into separate subcomponents. Important historical conceptualizations of psychopathy, the neuroscientific and empirical evidence for fear deficits in psychopathy are compared against this model. The empirical evidence is also subjected to a meta-analysis. We conclude that most studies have used the term fear generically, amassing different methods and levels of measurement under the umbrella term fear. Unlike earlier claims that psychopathy is related to general fearlessness, we show there is evidence that psychopathic individuals have deficits in threat detection and responsivity, but that the evidence for reduced subjective experience of fear in psychopathy is far less compelling. (PsycINFO Database Record

Cognitive and Ocular Factors Jointly Determine Pupil Responses under Equiluminance.

Changes in pupil diameter can reflect high-level cognitive signals that depend on central neuromodulatory mechanisms. However, brain mechanisms that adjust pupil size are also exquisitely sensitive to changes in luminance and other events that would be considered a nuisance in cognitive experiments recording pupil size. We implemented a simple auditory experiment involving no changes in visual stimulation. Using finite impulse-response fitting we found pupil responses triggered by different types of events. Among these are pupil responses to auditory events and associated surprise: cognitive effects. However, these cognitive responses were overshadowed by pupil responses associated with blinks and eye movements, both inevitable nuisance factors that lead to changes in effective luminance. Of note, these latter pupil responses were not recording artifacts caused by blinks and eye movements, but endogenous pupil responses that occurred in the wake of these events. Furthermore, we identified slow (tonic) changes in pupil size that differentially influenced faster (phasic) pupil responses. Fitting all pupil responses using gamma functions, we provide accurate characterisations of cognitive and non-cognitive response shapes, and quantify each responses dependence on tonic pupil size. These results allow us to create a set of recommendations for pupil size analysis in cognitive neuroscience, which we have implemented in freely available software.

Reward can modulate attentional capture, independent of top-down set

The traditional distinction between exogenous and endogenous attentional control has recently been enriched with an additional mode of control, termed “selection history.” Recent findings have indicated, for instance, that previously rewarded or punished stimuli capture more attention than their physical attributes would predict. As such, the value that is associated with certain stimuli modulates attentional capture. This particular influence has also been shown for endogenous attention. Although recent leads have emerged, elucidating the influences of reward on exogenous and endogenous attention, it remains unclear to what extent exogenous attention is modulated by reward when endogenous attention is already deployed. We used a Posner cueing task in which exogenous and endogenous cues were presented to guide attention. Crucially, the exogenous cue also indicated the reward value. That is, the color of the exogenous cue indicated how much reward could be obtained on a given trial. The results showed main effects of endogenous and exogenous attention (i.e., speeded reaction times when either cue was valid, as compared to when it was invalid). Crucially, an interaction between exogenous cue validity and reward level was observed, indicating that reward-based associative-learning processes rapidly influence attentional capture, even when endogenous attention has been actively deployed.

A latent variable analysis of the Psychopathy Checklist-Revised and behavioral inhibition system/behavioral activation system factors in North American and Swedish offenders.

An influential neurobiological model of personality is the Reinforcement Sensitivity Theory, which postulates how basic motivational systems (behavioral activation system [BAS], behavioral inhibition system [BIS]) can help account for the development and expression of individual differences in personality. Earlier research has documented a link between psychopathic personality and the BIS/BAS scale (Carver & White, 1994), which was developed to measure the behavioral inhibition and activation systems. However, no studies have examined how latent BIS/BAS factors and the 4 empirically derived Psychopathy Checklist-Revised (PCL-R) psychopathy factors (Hare & Neumann, 2008) are associated across different cultures. In the current study, structural equation modeling was used to determine how the 4 PCL-R factors were able to predict BIS/BAS factors using 2 large independent samples of male offenders (North American N = 908; Swedish N = 242). The results were in line with theory and revealed a negative relationship between the PCL-R Affective factor and the BIS factor as well as positive relationships between the PCL-R Antisocial and Lifestyle factors with the BAS factor. Overall, the results of the current study provide evidence of cross-cultural generalizability for the associations between the PCL-R factors and the BIS-BAS factors. Taken together, the PCL-R psychopathy factors were able to account for meaningful variance in the BIS-BAS factors and further support a dimensional approach to understanding the psychopathy construct across cultures.

Representational uncertainty in the brain during threat conditioning and the link with psychopathic traits

BACKGROUNDnPsychopathy has repeatedly been linked to disturbed associative learning from aversive events (i.e., threat conditioning). Optimal threat conditioning requires the generation of internal representations of stimulus-outcome contingencies and the rate with which these may change. Because mental representations are imperfect, there will always be uncertainty about the accuracy of representations in the brain (i.e., representational uncertainty). However, it remains unclear 1) to what extent threat conditioning is susceptible to different types of uncertainty in representations about contingencies during the acquisition phase and 2) how representational uncertainty relates to psychopathic features.nnnMETHODSnA computational model was applied to functional neuroimaging data to estimate uncertainty in representations of contingencies (CoUn) and the rate of change of contingencies (RUn), respectively, from brain activation during the acquisition phase of threat conditioning in 132 adolescents at risk of developing antisocial personality profiles. Next, the associations between these two types of representational uncertainty and psychopathy-related dimensions were examined.nnnRESULTSnThe left and right amygdala activations were associated with CoUn, while the bilateral insula andxa0the right amygdala were associated with RUn. Different patterns of relationships were found between psychopathic features and each type of uncertainty. Callous-unemotional traits and impulsive-irresponsible traits uniquely predicted increased CoUn, while only impulsive-irresponsible traits predicted increased RUn.nnnCONCLUSIONSnThe findings suggest that 1) the insula and amygdala differ in how these regions are affected by different types of representational uncertainty during threat conditioning and 2) CoUn and RUn have different patterns of relationships with psychopathy-related dimensions.

Top-down attention and selection history in psychopathy: evidence from a community sample

Psychopathy is a severe personality disorder, the core of which pertains to callousness, an entitled and grandiose interpersonal style often accompanied by impulsive and reckless endangerment of oneself and others. The response modulation theory of psychopathy states that psychopathic individuals have difficulty modulating top-down attention to incorporate bottom-up stimuli that may signal important information but are irrelevant to current goals. However, it remains unclear which particular aspects of attention are impaired in psychopathy. Here, we used 2 visual search tasks that selectively tap into bottom-up and top-down attention. In addition, we also looked at intertrial priming, which reflects a separate class of processes that influence attention (i.e., selection history). The research group consisted of 65 participants that were recruited from the community. Psychopathic traits were measured with the Psychopathic Personality Inventory (PPI; Uzieblo, Verschuere, & Crombez, 2007). We found that bottom-up attention was unrelated to psychopathic traits, whereas elevated psychopathic traits were related to deficits in the use of cues to facilitate top-down attention. Further, participants with elevated psychopathic traits were more strongly influenced by their previous response to the target. These results show that attentional deficits in psychopathy are largely confined to top-down attention and selection history.

Fearful Faces do Not Lead to Faster Attentional Deployment in Individuals with Elevated Psychopathic Traits

In the current study, a gaze-cueing experiment (similar to Dawel et al. 2015) was conducted in which the predictivity of a gaze-cue was manipulated (non-predictive vs highly predictive). This was done to assess the degree to which individuals with elevated psychopathic traits can use contextual information (i.e., the predictivity of the cue). Psychopathic traits were measured with the Self-Report Psychopathy Scale-Short Form (SRP-SF) in a mixed sample (undergraduate students and community members). Results showed no group difference in reaction times between high and non-predictive cueing blocks, suggesting that individuals with elevated psychopathic traits can indeed use contextual information when it is relevant. In addition, we observed that fearful facial expressions did not lead to a change in reaction times in individuals with elevated psychopathic traits, whereas individuals with low psychopathic traits showed speeded responses when confronted with a fearful face, compared to a neutral face. This suggests that fearful faces do not lead to faster attentional deployment in individuals with elevated psychopathic traits.

Visual attention in violent offenders: Susceptibility to distraction

Impairments in executive functioning give rise to reduced control of behavior and impulses, and are therefore a risk factor for violence and criminal behavior. However, the contribution of specific underlying processes remains unclear. A crucial element of executive functioning, and essential for cognitive control and goal-directed behavior, is visual attention. To further elucidate the importance of attentional functioning in the general offender population, we employed an attentional capture task to measure visual attention. We expected offenders to have impaired visual attention, as revealed by increased attentional capture, compared to healthy controls. When comparing the performance of 62 offenders to 69 healthy community controls, we found our hypothesis to be partly confirmed. Offenders were more accurate overall, more accurate in the absence of distracting information, suggesting superior attention. In the presence of distracting information offenders were significantly less accurate compared to when no distracting information was present. Together, these findings indicate that violent offenders may have superior attention, yet worse control over attention. As such, violent offenders may have trouble adjusting to unexpected, irrelevant stimuli, which may relate to failures in self-regulation and inhibitory control.