Walter Machado-Pinheiro

Load-dependent modulation of affective picture processing

Because of the biological significance of emotional stimuli, their processing is considered largely automatic. In the study reported herein, we tested the alternative hypothesis—namely, that the processing of emotional stimuli requires some level of attention. Our experiments utilized highly negative and arousing visual stimuli comprising mutilated bodies. All experiments employed a single task, which consisted of determining whether two peripheral bars were like oriented or not, thereby eliminating potential task-difference confounds that may have contaminated prior studies. Our results revealed that task-irrelevant unpleasant images slowed reaction time during the performance of the main task. Such interference was modulated by task difficulty as well as by alcohol consumption, showing that the processing of emotional visual stimuli is not immune to attentional manipulations. These results suggest that it is essential to utilize attentional manipulations that more fully consume attentional resources in order to demonstrate that the processing of emotional stimuli is resource limited.

Effects of acute alcohol intoxication on visuospatial attention

The aim of the present study was to examine the effects of acute alcohol intoxication on the spatial distribution of visual attention measured with simple reaction times (RTs) to targets presented over an extended region of the visual field. Control (n =10) and alcohol groups (n =14) were tested with the same protocol. Participants were tested in two different conditions; in Experiment I, participants were instructed to direct their visual attention to the centre, while in Experiment II they were asked to orient their attention covertly to both right and left, but not to the centre. Throughout participants were required to fixate a small cross in the centre of the computer screen. In the alcohol group, participants received an alcohol dose of 0.4 g/kg so as to produce a blood alcohol concentration (BAC) in the range of 0.08% during the experiments. The spatial distribution of RTs was analysed graphically with geostatistical methods and statistically through analysis of variance of particular regions of the visual field. Results showed that controls were able to direct their attention tightly towards the centre (Expt I) and also to divide attention (Expt II) to the right and left. Participants in the alcohol group fixed their attention more diffusely in the centre (Expt I) and were unable to disengage attention from the centre in Experiment II. We conclude that acute alcohol intoxication impairs the ability to dissociate attention from gaze. Human & Experimental Toxicology (2007) 26, 311-319

Emotional processing in obsessive–compulsive disorder

The aim of the present study was to investigate whether there are differences in emotional processing among people with obsessive-compulsive disorder, using Langs dimensional model of emotions. A total of 22 individuals with obsessive-compulsive disorder participated in the study and were compared to a control group (n=25). All participants assessed a set of photographs with emotional content (pleasant, neutral, unpleasant, and with obsessive-compulsive content) using the Self-Assessment Manikin pictorial scales for rating emotional valence (pleasant/unpleasant), arousal (calm/aroused) and dominance (controlling/controlled). The results show significant differences in the processing of emotional images among individuals with obsessive-compulsive disorder and the high predictive value of dominance for diagnosis.

Neurobiologia da regulação emocional: implicações para a terapia cognitivo-comportamental

Emotion regulation represents a crucial ability for social interaction, guiding behavior and modulatin g emotional expression. Current essay reviews the available lite rature on emotion regulation, points out the differ ent coping strategies and investigates the underlying neural network. Studies on cognitive reappraisal of emotion have noted a pa ttern of brain response characterized by the activation of the prefrontal c ortex associated with the reduction of amygdala acti vity. A modulatory mechanism between these structures has been suggested. Recent work showed that psychotherapeutic approaches may modify the dysfunctional neural circuitry associated with p sychiatric disorders. Results show that investigating the neurobiology of emotion regulation offers a potential repercussion on the understanding of the basis of psychiatric di sorders, orienting the development of applied studies and improving their clinical relevance.Emotion regulation represents a crucial ability for s cial interaction, guiding behavior and modulatin g emotional expression. Current essay reviews the available lite rature on emotion regulation, points out the differ ent coping strategies and investigates the underlying neural network. Studies on cognitive reappraisal of emotion have noted a pa ttern of brain response characterized by the activation of the prefrontal c ortex associated with the reduction of amygdala acti vity. A modulatory mechanism between these structures has been suggeste d. Rec nt work showed that psychotherapeutic approach es may modify the dysfunctional neural circuitry associated with p sychiatric disorders. Results show that investigating the neurobiology of emotion regulation offers a potential repercussion on the understanding of the basis of psychiatric di sor ers, orienting the development of applied studies and improving their clinical relevance.

Estímulos emocionais: processamento sensorial e respostas motoras

Emotion can be functionally considered as action dispositions preparing the organism for either avoidance- or approach- related behaviors. In order to prepare an appropriate behavioral output, the organism has to be efficient in the encoding of relevant stimuli. We herein present evidence from neuroimaging studies that seeing emotional and arousing pictures leads to greater activation in visual cortex than seeing neutral ones. In addition to this facilitation of sensory processing, emotional stimuli prompt somatic and vegetative reactions. Recordings of postural oscillations and heart rate while participants visualized a block of unpleasant pictures, revealed a significant reduction of body sway and bradycardia. A parallel investigation showed that reaction time also slows down after the visualization of negative pictures. Taken together, immobility, bradycardia and slower reaction time in the laboratory experimental set may reflect the engagement of the defensive system, resembling the defensive reactions to distant threatening stimuli in natural contexts. In summary, the affective system operates at an early level of sensory encoding and at the motor output favoring dispositions for appropriate actions.

Experimental context modulates warning signal effects

Previous studies have shown that saccadic eye responses but not manual responses were sensitive to the kind of warning signal used, with visual onsets producing longer saccadic latencies compared to visual offsets. The aim of the present study was to determine the effects of distinct warning signals on manual latencies and to test the premise that the onset interference, in fact, does not occur for manual responses. A second objective was to determine if the magnitude of the warning effects could be modulated by contextual procedures. Three experimental conditions based on the kind of warning signal used (visual onset, visual offset and auditory warning) were run in two different contexts (blocked and non-blocked). Eighteen participants were asked to respond to the imperative stimulus that would occur some milliseconds (0, 250, 500 or 750 ms) after the warning signal. The experiment consisted in three experimental sessions of 240 trials, where all the variables were counterbalanced. The data showed that visual onsets produced longer manual latencies than visual offsets in the non-blocked context (275 vs 261 ms; P < 0.001). This interference was obtained, however, only for short intervals between the warning and the stimulus, and was abolished when the blocked context was used (256 vs 255 ms; P = 0.789). These results are discussed in terms of bottom-up and top-down interactions, mainly those related to the role of attentional processing in cancelling out competitive interactions and suppressive influences of a distractor on the relevant stimulus.

Manual responses to visual stimuli: early and late facilitatory effects due to the offset of a peripheral cue

Manual and saccadic reaction times (MRTs and SRTs) are reduced when a warning signal precedes the onset of a target. The decreasing on SRTs observed after the offset of a fixation point has been called the gap effect. Different theories have been proposed to explain it. According to some authors, the offset also allows the saccadic system to generate a separate population of SRTs, the express saccades. Nevertheless there is no agreement about the influence of the offset of a peripheral stimulus on MRT. In two experiments we tested the effects of a peripheral visual offset used as preparatory signal on MRTs to a target after variable intervals. We found a reduction on MRT at short (200-300 ms) and long (1300-2000 ms) intervals after the peripheral offset. MRT distribution shifted toward short latencies, which sometimes formed a separate population. Since MRTs obtained at long intervals were affected by the introduction of catch trials, while MRTs at short intervals were not, we propose that two different mechanisms are involved in the decreasing of MRTs: warning and temporal expectancy. Our data support the hypothesis that the temporal component involved with the preparatory stages for motor responses can be shared by saccadic movements and key press responses, allowing the reduction on motor latencies after the visual offset in the gap paradigm. Our data corroborate the three components model for the gap effect. In our view, the question of the existence or not of a gap effect for manual responses is essentially conceptual.

Alcohol, emotion and attention: revisiting the Alcohol Myopia Theory

Among the known effects of alcohol on behavior, the modulation of cognitive functions (such as attention and memory), emotion, risk-taking and aggressive behavior are noteworthy. Here, we performed literature review in order to reinterpret alcohol effects on behavior according to the Alcohol Myopia Theory. According to this construct, there is a reduction of attentional resources during alcohol intoxication, which are primarily allocated to the most salient events in a given situation. The consequence is a hyperfocus directed to emotional situations when they are sufficiently relevant to grab attention, or a reduced attentional focus to emotional events in the presence of a relevant demanding task. The understanding of the mechanism mentioned above support the discussion of propositions toward the prevention of problems related to alcohol consumption. Importantly, the attentional allocation model provides inputs for a discussion on the scientifically-supported public health propositions aimed at preventing problems related to acute alcohol intoxication.

Captura da atenção por estímulos emocionais

In the present study, we investigated whether emotional pictures, presented as distractors, interfere in the performance of a competing neutral task. The participants had to discriminate the orientation of two bars presented bilaterally in the periphery (similar or dissimilar). Task difficulty was determined by the differences in orientation between the bars: the smallest orientation differences were used in the hardest task. Simultaneously, either neutral (people) or unpleasant (mutilated) pictures were presented centrally between the two bars. We observed that negative pictures interfere in the performance even in the harder task - the more attention demanding one. When the recognition of those pictures was tested, an advantage for the negative pictures was observed. These results showed that emotional stimuli are still processed even when the attentional load of a concurrent task is high. It is possible that those stimuli are potent drivers of privileged processing and can not be easily ignored.

Looking for the GAP effect in manual responses and the role of contextual influences in reaction time experiments

When the offset of a visual stimulus (GAP condition) precedes the onset of a target, saccadic reaction times are reduced in relation to the condition with no offset (overlap condition) - the GAP effect. However, the existence of the GAP effect for manual responses is still controversial. In two experiments using both simple (Experiment 1, N = 18) and choice key-press procedures (Experiment 2, N = 12), we looked for the GAP effect in manual responses and investigated possible contextual influences on it. Participants were asked to respond to the imperative stimulus that would occur under different experimental contexts, created by varying the array of warning-stimulus intervals (0, 300 and 1000 ms) and conditions (GAP and overlap): i) intervals and conditions were randomized throughout the experiment; ii) conditions were run in different blocks and intervals were randomized; iii) intervals were run in different blocks and conditions were randomized. Our data showed that no GAP effect was obtained for any manipulation. The predictability of stimulus occurrence produced the strongest influence on response latencies. In Experiment 1, simple manual responses were shorter when the intervals were blocked (247 ms, P < 0.001) in relation to the other two contexts (274 and 279 ms). Despite the use of choice key-press procedures, Experiment 2 produced a similar pattern of results. A discussion addressing the critical conditions to obtain the GAP effect for distinct motor responses is presented. In short, our data stress the relevance of the temporal allocation of attention for behavioral performance.