Emotional modulation of attention orienting: A classical conditioning study

Emotional modulation of attention shifting was investigated in Posner's (1980) spatial orienting task by conditioning the attention cue to an aversive white noise. Prior to the attention task, the Conditioning group received a 90dB white noise unconditioned stimulus (UCS) contingent upon the frame-lit rectangle attention cue, while the Control group received non-contingent presentations. The Conditioning group evidenced greater skin conductance responses to the frame-lit rectangle in the conditioning phase, reflecting an electrodermal conditioned response. In the attention phase, the frame-lit rectangle served as the attention cue in the spatial orienting task. The Conditioning group showed equally fast reaction times (RTs) to targets presented outside the location of the cue as to targets at the same location as the cue, reflecting elimination of the cognitive cost usually involved in shifting attention. The Control group evidenced the regular cost of shifting attention away from the location of the cue. The Conditioning group also evidenced a larger N1-component with a parietal distribution of the event-related brain potentials to the cue and a larger N1-component at the frontal regions to targets presented outside the cued location. This suggests that both visual orienting to the cue and attention shifting from cue to target on invalid trials were amplified by the emotional salience attached to the cue through the classical conditioning procedure.     

Implicit and explicit emotional behavior and mindfulness

The objective of this study was to examine whether the “step back and watch” attitude of mindfulness manifests in less emotional behavior. We hypothesized that the “acceptance” facet of mindfulness, but not the “presence” facet, is negatively associated with the magnitude of emotional behavior in four tests, i.e., (1) rating of words, (2) rating of aversive and neutral pictures, and (3) evaluative conditioning (EC). Additionally, we hypothesized that (4) the acceptance facet is associated with increased reaction time (RT) in an emotional Stroop test, and that the presence facet is associated with decreased RT and lower error rate. The sample consisted of N = 247 non-clinical adults and was tested in a cross-sectional study. The results provide partial evidence that the acceptance facet of mindfulness may be associated with less aversive reactions towards aversive stimuli. Future studies should substantiate these findings but also determine their clinical relevance.     

Noradrenergic enhancement of associative fear memory in humans

Ample evidence in animals and humans supports the noradrenergic modulation in the formation of emotional memory. However, in humans the effects of stress on emotional memory are traditionally investigated by declarative memory tests (e.g., recall, recognition) for non-associative emotional stimuli (e.g., stories, pictures). Given that anxiety disorders are thought to originate from associative learning processes and are characterized by distressing emotional responses, the existing literature seems to be inconclusive for the understanding of these disorders. Here, we tested whether noradrenaline strengthens the emotional expression of associative fear memory by using a differential fear conditioning procedure in humans. Stimulation of the noradrenergic system by the administration of yohimbine HCl (20 mg) during memory formation did not directly augment the differential startle fear response 48 h later. Yet, the other retention tests uncovered that the administration of yohimbine HCl contrary to placebo pill extensively delayed the process of extinction learning and generated a superior recovery of fear (i.e., reinstatement and reacquisition). Conversely, the yohimbine HCl manipulation did not affect the skin conductance responding and the US expectancy ratings, emphasizing the concept of multiple memory systems. To our knowledge this is the first demonstration in humans that increased noradrenaline release during or shortly after a stressful event strengthens the formation of associative fear memory traces. The present findings suggest that noradrenaline may play an important role in the etiology and maintenance of anxiety disorders.     

Evaluative conditioning without directly experienced pairings of the conditioned and the unconditioned stimuli

Evaluative conditioning (EC) is the valence change of a stimulus (conditioned stimulus, CS) that is due to the previous pairing with another stimulus (unconditioned stimulus, US). We investigated whether EC can occur also when the CS–US pairings are not experienced directly by the participant but are implied by other events that the participant encounters. In two experiments, positive USs were presented in some trials and negative USs in other trials. Afterwards, participants were given information from which it was possible to conclude that CSs were covertly present during these trials. Finally, the valence of these CSs was registered using both implicit (Implicit Association Test, affective priming) and explicit measures (valence ratings). In line with the assumption that EC effects can be based on CS–US pairings that are not directly experienced, the valence of the CSs changed in the direction of the US with which they were covertly paired. This effect was observed both on explicit and on implicit measures. We argue that several aspects of our results are in line with propositional models of EC and fit less well with association formation models.     

Cortisol Response Following Exposure Treatment for PTSD in Rape Victims

This study examined changes in salivary cortisol levels pre- to posttreatment in adult female rape victims diagnosed with posttraumatic stress disorder (PTSD) randomly assigned to be treated with either prolonged exposure therapy or eye movement desensitization and reprocessing. Salivary cortisol was collected at baseline, Session 3, and Session 9. A significant decrease in salivary cortisol levels was observed in individuals classified as treatment responders in both treatment conditions. Findings suggest that successful exposure-based treatments for PTSD that result in trauma-related and depressive symptom reduction may impact the action of the hypothalamic–pituitary–adrenal axis as measured by changes in level of salivary cortisol from pre- to posttreatment.     

Eye movements during recall of aversive memory decreases conditioned fear

Cognitive-behavioral therapy for anxiety disorders typically involves exposure to the conditioned stimulus (CS). Despite its status as an effective and primary treatment, many patients do not show clinical improvement or relapse. Contemporary learning theory suggests that treatment may be optimized by adding techniques that aim at revaluating the aversive consequence (US) of the feared stimulus. This study tested whether US devaluation via a dual task – imagining the US while making eye movements – decreases conditioned fear. Following fear acquisition one group recalled the US while making eye movements (EM) and one group merely recalled the US (RO). Next, during a test phase, all participants were re-presented the CSs. Dual tasking, relative to the control condition, decreased memory vividness and emotionality. Moreover, only in the dual task condition reductions were observed in self-reported fear, US expectancy, and CS unpleasantness, but not in skin conductance responses. Findings provide the first evidence that the dual task decreases conditioned fear and suggest it may be a valuable addition to exposure therapy.     

Classical conditioning,awareness, and brain systems

Memory is composed of several different abilities that are supported by different brain systems. The distinction between declarative (conscious) and nondeclarative (non-conscious) memory has proved useful in understanding the nature of eyeblink classical conditioning – the best understood example of classical conditioning in vertebrates. In delay conditioning, the standard procedure, conditioning depends on the cerebellum and brainstem and is intact in amnesia. Trace conditioning, a variant of the standard procedure, depends additionally on the hippocampus and neocortex and is impaired in amnesia. Recent studies have sharpened the contrast between delay and trace conditioning by exploring the importance of awareness. We discuss these new findings in relation to the brain systems supporting eyeblink conditioning and suggest why awareness is important for trace conditioning but not for delay conditioning.     

Duration perception of emotional stimuli: Using evaluative conditioning to avoid sensory confounds

It has been found that emotional pictures are estimated to last longer than neutral ones. However, emotional and neutral stimuli often differ in their physical characteristics, too. Since this might also affect time perception, we present a method disentangling a possible confounding regarding the processing of physically different stimulus material. In the evaluative condition paradigm, participants, at first, learnt the association of neutral images with a certain Landolt ring and of emotional images with another Landolt ring with a different gap position. The conditioned Landolt rings were subsequently used in a temporal bisection task. In two experiments, the results revealed a temporal overestimation of Landolt rings conditioned with emotional pictures compared to neutral pictures showing that the temporal overestimation of emotional stimuli cannot be attributed to perceptual differences between neutral and emotional stimuli. The method provides the potential for investigating emotional effects on various perceptual processes.     

Revisiting the relation between contingency awareness and attention: Evaluative conditioning relies on a contingency focus

Although evaluative conditioning has occasionally been demonstrated in the absence of contingency awareness, many recent studies imply that its acquisition depends on the availability of attentional resources during conditioning. In previous experiments attention has typically been manipulated in a general way rather than looking at the particular focus of attention. The present study investigated the role of a focus on the CS–US contingency. Two separate distraction tasks were designed that either diverted attention from the stimuli or directed it to the stimuli while drawing attention away from the contingency between the stimuli. Both types of distraction were shown to eliminate evaluative conditioning. Significant evaluative conditioning was observed in a third group of participants who were required to attend the contingencies. A mediation analysis showed that the observed discrepancy in evaluative conditioning effects between groups was mediated by contingency awareness. The results imply that attention in terms of a stimulus focus is not sufficient for evaluative conditioning to occur. Rather, attention to the contingencies between stimuli appears to be crucial in evaluative conditioning, because it is supposed to foster the acquisition of contingency awareness.