A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction

A design for an inexpensive and reliable olfactometer is presented. The design has several advantages for fMRI and electrophysiology investigators. These advantages include relatively rapid odorant rise times, computer control, multiple odor administration, and no ferrous materials near the subjects. In addition, the device is contamination resistant, and, because the air is neither warmed nor humidified, it is unlikely to become an incubator for bacteria. The olfactometer is constructed of off-the-shelf chromatography parts that require little modification.     

Emotional expressions and visual search efficiency: specificity and effects of anxiety symptoms

Although facial expressions are thought to vary in their functional impact on perceivers, experimental demonstration of the differential effects of facial expressions on behavior are lacking. In the present study, we examined the effects of exposure to facial expressions on visual search efficiency. Participants (n = 31) searched for a target in a 12 location circle array after exposure to an angry, disgusted, fearful, happy, or neutral facial expression for 100 ms or 500 ms. Consistent with predictions, exposure to a fearful expression prior to visual search resulted in faster target identification compared to exposure to other facial expressions. The effects of other facial expressions on visual search did not differ from each other. The fear facilitating effect on visual search efficiency was observed at 500-ms but not at 100-ms presentations, suggesting a specific temporal course of the facilitation. Subsequent analysis also revealed that individual differences in fear of negative evaluation, trait anxiety, and obsessive-compulsive symptoms possess a differential pattern of association with visual search efficiency. The experimental and clinical implications of these findings are discussed.     

Fearful expressions gain preferential access to awareness during continuous flash suppression

Rapid evaluation of ecologically relevant stimuli may lead to their preferential access to awareness. Continuous flash suppression allows assessment of affective processing under conditions in which stimuli have been rendered invisible due to the strongly suppressive nature of dynamic noise relative to static images. The authors investigated whether fearful expressions emerge from suppression into awareness more quickly than images of neutral or happy expressions. Fearful faces were consistently detected faster than neutral or happy faces. Responses to inverted faces were slower than those to upright faces but showed the same effect of emotional expression, suggesting that some key feature or features in the inverted faces remained salient. When using stimuli solely representing the eyes, a similar bias for detecting fear emerged, implicating the importance of information from the eyes in the preconscious processing of fear expressions.     

The emotional attentional blink is robust to divided attention

The emotional attentional blink (EAB) refers to a temporary impairment in the ability to identify a target when it is preceded by an emotional distractor. It is thought to occur because the emotional salience of the distractor exogenously captures attention for a brief duration, rendering the target unattended and preventing it from reaching awareness. Here we tested the extent to which the EAB can be attenuated by inducing a diffuse top-down attentional state, which has been shown to improve target identification in an analogous attentional phenomenon, the attentional blink. Rapid sequences of landscape images were presented centrally, and participants reported the orientation of a ± 90° rotation of a landscape target. To induce a diffuse state of attention, participants were given a secondary task of monitoring for the appearance of a colored dot in the periphery. We found that emotional distractors impaired target recognition performance to comparable extents, regardless of whether or not participants concurrently performed the peripheral-monitoring task. Moreover, we found that performance of the secondary task led to an impaired ability to ignore neutral distractors. Subjective ratings of target vividness mirrored the behavioral accuracy, with frequent reports of intermediate levels of vividness suggesting that the EAB might impair target visibility in a graded manner. Our results demonstrate that the EAB is robust to manipulations of top-down attention, suggesting that the temporary capture of attention by emotionally salient stimuli involves processes that are distinct from those that produce the attentional blink.     

Clinical versus mechanical prediction: a meta-analysis

The process of making judgments and decisions requires a method for combining data. To compare the accuracy of clinical and mechanical (formal, statistical) data-combination techniques, we performed a meta-analysis on studies of human health and behavior. On average, mechanical-prediction techniques were about 10% more accurate than clinical predictions. Depending on the specific analysis, mechanical prediction substantially outperformed clinical prediction in 33%-47% of studies examined. Although clinical predictions were often as accurate as mechanical predictions, in only a few studies (6%-16%) were they substantially more accurate. Superiority for mechanical-prediction techniques was consistent, regardless of the judgment task, type of judges, judges' amounts of experience, or the types of data being combined. Clinical predictions performed relatively less well when predictors included clinical interview data. These data indicate that mechanical predictions of human behaviors are equal or superior to clinical prediction methods for a wide range of circumstances.     

Effort-based decision-making in major depressive disorder: A translational model of motivational anhedonia

Anhedonia is a core feature of major depressive disorder (MDD), but the precise nature of anhedonic symptoms is unknown. Whereas anhedonia has traditionally been viewed as a deficit in the experience of pleasure, more recent evidence suggests that reduced anticipation and motivation may also be a core feature of this symptom. Here, we provide data from a study in MDD patients and healthy controls using a translational measure of reward motivation, the Effort Expenditure for Rewards Task (EEfRT or "effort"). This task offers subjects a series of trials where they may choose to expend more or less effort for the opportunity to win varying amounts of monetary rewards. We found that MDD patients were less willing to expend effort for rewards than controls. Additionally, we observed that patients were less able to effectively use information about magnitude and probability of rewards to guide their choice behavior. Finally, within the MDD patient group, duration of the current episode was a significant negative predictor of EEfRT task performance. These findings offer novel support for theoretical models proposing that anhedonia in MDD may reflect specific impairments in motivation and reward-based decision-making. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Attentional control in OCD and GAD: specificity and associations with core cognitive symptoms

Obsessive–compulsive disorder (OCD) and generalized anxiety disorder (GAD) are both defined by excessive negatively-valenced cognitions. Although obsessional thoughts are considered essential to OCD and perseverative worry is considered essential to GAD, these excessive cognitions have been found to co-occur in both disorders. Accordingly, a common diathesis may influence the emergence of excessive thoughts in both disorders. The present study examined deficits in attentional control as a cognitive vulnerability that may contribute to both obsessional thought and perseverative worry. Patients with OCD (n = 30), GAD (n = 29), and non-clinical controls (NCC; n = 29) completed measures of obsessional thoughts, perseverative worry, and attentional control. Deficits in self-reported attentional control were found in both OCD and GAD relative to the NCC. However, attentional control was only related to excessive cognition in the GAD patient group, where deficits were associated with increased perseverative worry. Mediational modeling suggested that trait anxiety mediated the relationship between attentional control and perseverative worry in GAD. Implications of these findings for conceptualizing the role of attentional control in the genesis of excessive cognitions in OCD and GAD are discussed.     

An emotion-induced attentional blink elicited by aversively conditioned stimuli

The current study examines whether aversively conditioned stimuli can modulate attention to such a degree that they impair the perception of subsequently presented nonemotional targets. In the initial phase of this study, participants viewed 3 categories of photographs, 1 of which was paired with an aversive noise. Following conditioning, participants searched for a target embedded within a series of 17 rapidly presented images on each trial. Critically, a conditioned or unconditioned item from the initial phase appeared 200 ms or 800 ms before the target. At 200-ms lags but not 800-ms lags, the conditioned images impaired target detection relative to the other distractors. Thus, temporary visual deficits can be induced by otherwise neutral distractors whose aversive associations have only recently been learned.     

The naked truth: Positive,arousing distractors impair rapid target perception

Emotional stimuli tend to capture and hold attention more than non-emotional stimuli do. Aversive pictures have been found to impair perception of visual targets even after the emotional information has disappeared. The benefits of such interlinked emotion and attention systems have sometimes been discussed within an evolutionary framework, with a survival advantage attributed to early detection of threatening stimuli. However, consistent with recent suggestions that attention is drawn to arousing stimuli regardless of whether they are positive or negative, the current investigation found that erotic distractors—generally rated as both pleasing and arousing—consistently elicited a transient “emotion-induced blindness” similar to that caused by aversive distractors (Experiment 1). This effect persisted despite performance-based monetary incentives to ignore the distractors (Experiment 2), and following attentional manipulations that reduced interference from aversive images (Experiment 3). The findings indicate that positively arousing stimuli can spontaneously cause emotion-induced deficits in visual processing, just as aversive stimuli can.