TRoPICALS: a computational embodied neuroscience model of compatibility effects

Perceiving objects activates the representation of their affordances. For example, experiments on compatibility effects showed that categorizing objects by producing certain handgrips (power or precision) is faster if the requested responses are compatible with the affordance elicited by the size of objects (e.g., small or large). The article presents a neural-network architecture that provides a general framework to account for compatibility effects. The model was designed with a methodological approach (computational embodied neuroscience) that aims to provide increasingly general accounts of brain and behavior (4 sources of constraints are used: neuroscientific data, behavioral data, embodied systems, reproduction of learning processes). The model is based on 4 principles of brain organization that we claim underlie most compatibility effects. First, visual perception and action are organized in the brain along a dorsal neural pathway encoding affordances and a ventral pathway encoding goals. Second, the prefrontal cortex within the ventral pathway gives a top-down bias to action selection by integrating information on stimuli, context, and goals. Third, reaction times depend on dynamic neural competitions for action selection that integrate bottom-up and top-down information. The congruence or incongruence between affordances and goals explains the different reaction times found in the experiments. Fourth, as words trigger internal simulations of their referents, they can cause compatibility effects as objects do. We validated the model by reproducing and explaining 3 types of compatibility effects and showed its heuristic power by producing 2 testable predictions. We also assessed the explicative power of the model by comparing it with related models and showed how it can be extended to account for other compatibility effects.     

Bullying as a social process: The role of group membership in students' perception of inter-group aggression at school

Bullying is a widespread social phenomenon involving both individual and group variables. The present study was aimed at analyzing how students' perception of a bullying episode might be influenced by group and context variables. A convenience sample of 455 adolescents read a short story, in which the in-group role (bully vs. victim) and level of teacher likeability (high vs. low) were manipulated. Participants were asked to evaluate their own group and an out-group, in terms of four dependent variables: liking, right to use the basketball court, attribution of blame, and attribution of punishment. Data showed a strong participant in-group bias and a generalized tendency to favor the in-group, especially when it was the victimized group. Conversely, the manipulation of teacher likeability did not affect students' perception of bullying, except for girls' attribution of punishment. Lastly, a clear gender effect emerged, in that boys accepted physical bullying more readily than girls did. Results are discussed in terms of group dynamics and preadolescent social identity concerns.     

Classroom Collective Moral Disengagement Scale: Validation in Czech adolescents

Moral disengagement (MD) provides a fruitful framework for understanding how adolescents could attenuate moral self-regulation and behave aggressively. While measures of individual MD have a long tradition, only recently have Gini, Pozzoli, and Bussey developed an instrument measuring collective MD (CMD): Classroom Collective Moral Disengagement Scale (CCMDS). The present study examined psychometric properties of a Czech version of the scale with a sample of 662 adolescents, aged 11–15, from 20 randomly selected elementary schools. Participants completed the scale and a peer-rating measure of bullying, victimization, and defending. The analyses indicated that the CCMDS could be considered a unidimensional gender-invariant scale with very good internal consistency and criterion validity. Importantly, the scale score aggregated at the classroom level was associated with three bullying behaviors: bullying, victimization, and defending. The results support the use of the CCMDS as a promising measure of CMD.     

Reincarnation and infinite punishment in hell

In the first part of the paper, I argue that Christians should incorporate the theory of reincarnation into their belief system. The problem of the apparent disproportion between finite human sin and infinite punishment in Hell becomes far more tractable against the background of reincarnation. In the second part of the paper, I address and answer three objections that may be raised against a Christian theory of reincarnation. The first objection is based on the role of memory in identity, the second points to the essential unity of body and soul, and the third revolves around the suggestion that living multiple lives may more easily lead to damnation than to salvation.     

How affordances associated with a distractor object affect compatibility effects: A study with the computational model TRoPICALS

Seeing an object activates both visual and action codes in the brain. Crucial evidence supporting this view is the observation of object to response compatibility effects: perception of an object can facilitate or interfere with the execution of an action (e.g., grasping) even when the viewer has no intention of interacting with the object. TRoPICALS is a computational model that proposes some general principles about the brain mechanisms underlying compatibility effects, in particular the idea that top-down bias from prefrontal cortex, and whether it conflicts or not with the actions afforded by an object, plays a key role in such phenomena. Experiments on compatibility effects using a target and a distractor object show the usual positive compatibility effect of the target, but also an interesting negative compatibility effect of the distractor: responding with a grip compatible with the distractor size produces slower reaction times than the incompatible case. Here, we present an enhanced version of TRoPICALS that reproduces and explains these new results. This explanation is based on the idea that the prefrontal cortex plays a double role in its top-down guidance of action selection producing: (a) a positive bias in favour of the action requested by the experimental task; (b) a negative bias directed to inhibiting the action evoked by the distractor. The model also provides testable predictions on the possible consequences of damage to volitional circuits such as in Parkinsonian patients.     

Is severe obesity a form of addiction? Rationale, clinical approach, and controlled clinical trial.

For many, obesity is just a problem of energy input and expenditure: more energy input than expenditure. However, the clinical practice and epidemiological data clearly show that weight control is more complex than expected by this simple equation. This is particularly true in morbid obesity, a form of severe obesity in which a person's Body Mass Index (BMI, kg/m(2)) is over 40. If we compare the definitions and diagnostic criteria for "dependence" and "addiction" with the situation of many severe obese subjects, it is apparent that they match very well. Further, different neurological studies confirm this similarity: both addiction and obesity patients have a deficiency of dopamine receptors. Nevertheless, when we compare many of the actual obesity treatments with the ones used in the area of addictions it is possible to find relevant differences: obesity treatments neither consider different levels of type and intensity of care, nor a multidimensional approach. To overcome these limitations, in this paper we propose a bio-psychosocial approach in which the genetic influence (lack of dopamine receptors) is matched by psychosocial issues (pressure for thinness and diet as main body image dissatisfaction treatment). Further, the paper outlines how this approach may influence the treatment options, by focusing both on the lessons coming from actual addiction treatment and the opportunities offered by virtual reality. Finally, the paper presents and discusses the outcome of a controlled trial, based on the proposed approach, including a 6-month follow-up (211 morbid obese females with a BMI of >40 and a documented history of failures.     

Sequence learning in pianists and nonpianists: An fMRI study of motor expertise

Previous studies of motor learning have proposed a distinction between fast and slow learning, but these mechanisms have rarely been examined simultaneously. We examined the influence of longterm motor expertise (slow learning) while pianists and nonpianists performed alternating epochs of sequenced and random keypresses in response to visual cues (fast learning) during functional neuroimaging. All of the participants demonstrated learning of the sequence as demonstrated by decreasing reaction times (RTs) on sequence trials relative to random trials throughout the session. Pianists also demonstrated faster RTs and superior sequence acquisition in comparison with nonpianists. Withinsession decreases in bilateral sensorimotor and parietal activation were observed for both groups. Additionally, there was more extensive activation throughout the session for pianists in comparison with nonpianists across a network of primarily right-lateralized prefrontal, sensorimotor, and parietal regions. These findings provide evidence that different neural systems subserve slow and fast phases of learning.     

Individual capacity differences predict working memory performance and prefrontal activity following dopamine receptor stimulation

Dopamine receptors are abundant in the prefrontal cortex (PFC), a critical region involved in working memory. This pharmacological fMRI study tested the relationships between dopamine, PFC function, and individual differences in working memory capacity. Subjects performed a verbal delayed-recognition task after taking either the dopamine receptor agonist bromocriptine or a placebo. Behavioral effects of bromocriptine treatment depended on subjects’ working memory spans, with the greatest behavioral benefit for lower span subjects. After bromocriptine, PFC activity was positively correlated with a measure of cognitive efficiency (RT slope) during the probe period of the task. Less efficient subjects with slower memory retrieval rates had greater PFC activity, whereas more efficient subjects had less activity. After placebo, these measures were uncorrelated. These results support the role of dopamine in verbal working memory and suggest that dopamine may modulate the efficiency of retrieval of items from the contents of working memory. Individual differences in PFC dopamine receptor concentration may thus underlie the behavioral effects of dopamine stimulation on working memory function.